Therapeutic potential of selective peroxisome proliferator-activated receptor alpha modulators (SPPARMα) for management of patients with atherogenic dyslipidemia

Therapeutic potential of selective peroxisome proliferator-activated receptor alpha modulators (SPPARMα) for management of patients with atherogenic dyslipidemia

By Heather Nelson Cortes, PhD and Kevin C Maki, PhD

 

Atherosclerotic cardiovascular disease (ASCVD) is associated with a significant public health burden around the world.  It is further exacerbated by chronic lifestyle-related diseases, such as visceral obesity, type 2 diabetes mellitus (T2D) and non-alcoholic fatty liver disease.  The morbidity and mortality of ASCVD is particularly high in low- and middle- income countries, which also have the largest number of people with obesity and diabetes.1-3  In these populations atherogenic dyslipidemia is a significant unmet clinical need.  Elevated plasma triglycerides (TG), with or without low levels of high-density lipoprotein cholesterol (HDL-C), are modifiable ASCVD risk factors, especially in insulin resistant conditions such as T2D.4

 

Some current ASCVD prevention guidelines recommend peroxisome proliferator-activated receptor alpha (PPARα) agonists (e.g., fibrates) for management of hypertriglyceridemia after statins.5  Unfortunately, these PPAR-α agonists have low potency and limited selectivity for PPARα.  They also have pharmacokinetic interactions and other side effects, including an increased risk of myopathy with gemfibrozil in combination with statin and reversible elevation in serum creatinine with fenofibrate, as well as liver enzyme elevation.6-9  Pemafibrate, a novel selective peroxisome proliferator-activated receptor alpha modulator (SPPARMα), which has a unique receptor-cofactor binding profile to identify the most potent molecules with PPARα-mediated effects while limiting unwanted side effects, has recently been developed.

 

Given the clear need for new therapeutic options for ASCVD, the Joint Consensus Panel from the International Atherosclerosis Society and the Residual Risk Reduction Initiative reviewed the scientific literature to help to determine if it is possible for pemafibrate to improve upon the beneficial lipid effects and safety profile demonstrated for PPARα agonists.10  In a randomized, double-blind clinical trial of 33 patients with atherogenic dyslipidemia, pemafibrate led to markedly decreased TG-rich lipoprotein levels and significantly increased concentrations of HDL-C, apolipoprotein (apo) A-I and apo-A-II, as well as improved markers of HDL function including pre-beta-HDL, smaller HDL particles (HDL3), and increased macrophage cholesterol efflux capacity.11  A pooled analysis of phase II/III studies showed that pemafibrate therapy over 12-24 weeks led to significant improvements in liver function tests (alanine aminotransferase, gamma glutamyl transferase, bilirubin).12  Also, unlike fenofibrate, pemafibrate did not elevate serum creatinine for up to 52 weeks in patients with or without pre-existing renal dysfunction.13  In general, the studies conducted to date have demonstrated that pemafibrate is well tolerated, especially with regard to renal and hepatic function, and that it may help in the management of atherogenic dyslipidemia, particularly by lowering elevated TG-rich lipoproteins and remnant cholesterol levels that are common in overweight patients with T2D.10

 

This Joint Consensus Panel concluded that pemafibrate, a SPPARMα agonist, represents a novel therapeutic class, distinct from fibrates according to its pharmacological activity, with a safe hepatic and renal profile.10  The Panel also recognized that the ongoing Pemafibrate to Reduce Cardiovascular Outcomes by Reducing Triglycerides in Patients with Diabetes (PROMINENT) trial of 10,000 patients with T2D, elevated TG, and low levels of HDL-C will help to determine if pemafibrate can be safely used to reduce residual cardiovascular risk.

 

References

  1. Joseph P, Leong D, McKee M, et al. Reducing the global burden of cardiovascular disease. Part 1: the epidemiology and risk factors. Circ Res. 2017;121:677–94.
  2. World Health Organization. Fact sheet. Obesity and overweight. http:// www.who.int/news-room/fact-sheets/detail/obesity-and-overweight. Accessed 21 Jan 2019.
  3. NCD Countdown 2030 collaborators. NCD Countdown 2030: worldwide trends in non-communicable disease mortality and progress towards Sustainable Development Goal target 3.4. Lancet. 2018;392:1072–88.
  4. Varbo A, Freiberg JJ, Nordestgaard BG. Remnant cholesterol and myocardial infarction in normal weight, overweight, and obese individuals from the Copenhagen General Population Study. Clin Chem. 2018;64:219–30.
  5. Piepoli MF, Hoes AW, Agewall S, et al. 2016 European Guidelines on cardiovascular disease prevention in clinical practice: the Sixth Joint Task Force of the European Society of Cardiology and Other Societies on Cardiovascular Disease Prevention in Clinical Practice (constituted by representatives of 10 societies and by invited experts) Developed with the special contribution of the European Association for Cardiovascular Prevention & Rehabilitation (EACPR). Eur Heart J. 2016;37:2315–81.
  6. Davidson MH. Statin/fibrate combination in patients with metabolic syndrome or diabetes: evaluating the risks of pharmacokinetic drug interactions. Expert Opin Drug Saf. 2006;5:145–56.
  7. Mychaleckyj JC, Craven T, Nayak U, et al. Reversibility of fenofibrate therapy-induced renal function impairment in ACCORD type 2 diabetic participants. Diabetes Care. 2012;35:1008–14.
  8. Davis TM, Ting R, Best JD, et al. Effects of fenofibrate on renal function in patients with type 2 diabetes mellitus: the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) Study. Diabetologia. 2011;54:280–90.
  9. Hedrington MS, Davis SN. Peroxisome proliferator-activated receptor alpha-mediated drug toxicity in the liver. Expert Opin Drug Metab Toxicol. 2018;14:671–7.
  10. Fruchart J-C, Santos RD, Aguilar-Salinas C, et al. The selective peroxisome proliferator-activated receptor alpha modulator (SPPARMα) paradigm: conceptual framework and therapeutic potential. A consensus statement from the International Atherosclerosis Society (IAS) and the Residual Risk Reduction Initiative (R3i) Foundation. Cardiovasc Diabetol. 2019;18:71.
  11. Yamashita S, Arai H, Yokote K, et al. Effects of pemafibrate (K-877) on cholesterol efflux capacity and postprandial hyperlipidemia in patients with atherogenic dyslipidemia. J Clin Lipidol. 2018;12:1267–79.
  12. Matsuba I, Matsuba R, Ishibashi S, et al. Effects of a novel selective peroxisome proliferator-activated receptor-α modulator, pemafibrate, on hepatic and peripheral glucose uptake in patients with hypertriglyceridemia and insulin resistance. J Diabetes Investig. 2018;9:1323–32.
  13. Yokote K, Yamashita S, Arai H, et al. A pooled analysis of pemafibrate Phase II/III clinical trials indicated significant improvement in glycemic and liver function-related parameters. Atheroscler Suppl. 2018;32:155.

 

Photo by Lucas Vasques

Suboptimal Triglyceride Levels Among Statin Users in the National Health and Nutrition Examination Survey

Suboptimal Triglyceride Levels Among Statin Users in the National Health and Nutrition Examination Survey

By Heather Nelson Cortes, PhD and Kevin C Maki, PhD

 

Statin therapy is the primary treatment for dyslipidemia, even in those with moderately elevated triglycerides (TG).1  Hypertriglyceridemia, an independent risk factor of coronary heart disease (CHD), is defined as fasting TG >150 mg/dL.2  Meta-analyses have shown a 1.7-fold greater risk for CHD in those in the highest TG tertile compared to those in the lowest tertile.2,3  In a more recent longitudinal, real-world administrative database analysis, increased cardiovascular disease risk and direct healthcare costs were associated with hypertriglyceridemia, despite statin therapy and controlled low-density lipoprotein cholesterol (LDL-C) when compared to those with TG <150 mg/dL.4,5  Another study has also reported that approximately one-third of patients treated for dyslipidemia still have suboptimal TG levels.6

In the US population, limited data have been available on the prevalence and impact of hypertriglyceridemia in patients treated for dyslipidemia or with normal LDL-C levels, especially given the increase in statin use.  To help address this gap, Fan et al. analyzed National Health and Nutrition Examination Surveys (NHANES) from 2007-2014 to determine the prevalence of elevated TG levels in adults with and without statin use, as well as the associated 10-year predicted atherosclerotic cardiovascular disease (ASCVD) risk.7  The study included 9,593 US adults aged 20 years (219.9 million projected) and determined the proportion of persons with TG levels according to the categories of <150, 150-199, 200-499, and 500 mg/dL for both non-statin and statin users.

Proportion of US adults According to TG Category7

 

<150 mg/dL

150-199 mg/dL

≥ 200 mg/dL

Non-statin users

75.3%

12.8%

11.9%

Statin Users

68.4%

16.2%

15.4%

 

Among those with LDL-C <100 mg/dL (or <70 mg/dL in those with ASCVD), 27.6% had TG 150 mg/dL, despite statin use.  Significantly greater odds of TG 150 mg/dL in statin users were associated with higher age, higher body mass index, lower high-density lipoprotein cholesterol, higher LDL-C, and diabetes.  The estimated mean 10-year ASCVD risk from TG <150 to 500 mg/dL, ranged from 6.0-15.6% in those not taking statins, and 11.3-19.1% in statin users. This translates to a predicted 3.4 million ASCVD events over the next 10 years in those with TG 150 mg/dL.

Comment.  Based on these results in US adults, suboptimal TG levels are found in ~25% of the overall population and nearly one-third of adults on statin therapy.  TG elevation is associated with increased ASCVD risk, even when the LDL-C level is low.8  Lifestyle therapies are key in the management of an elevated TG level, including increased physical activity, weight loss, reduced glycemic load and alcohol restriction.1,9  The recently published results from the Reduction of Cardiovascular Events with Icosapent Ethyl (REDUCE-IT) trial demonstrated that ASCVD event risk was lowered by an impressive 25% in statin-treated high-risk patients with elevated TG by the addition of 4 g/d of icosapent ethyl (eicosapentaenoic acid [EPA] ethyl esters).10  Two additional large-scale trials are underway with TG-lowering drug therapies (Outcomes Study to Assess Statin Residual Risk Reduction with Epanova in High CV Risk Patients [STRENGTH] and Pemafibrate to Reduce Cardiovascular Outcomes by Reducing Triglycerides in Patients with Diabetes [PROMINENT]), which are evaluating effects of EPA + docosahexaenoic acid (DHA) carboxylic acids and pemafibrate, respectively.11,12  The results from the present survey suggest that the population-attributable risk due to elevated TG in the US is substantial, which underscores the importance of recognizing hypertriglyceridemia as a marker for ASCVD risk that can be addressed through lifestyle and pharmacologic therapies.

References

 

  1. Stone NJ, Robinson JG, Lichtenstein AH, et al. American College of Cardiology/American Heart Association task force on practice guidelines. 2013 ACC/AHA guideline on the treatment of blood cholesterol to reduce atherosclerotic cardiovascular risk in adults: a report of the American College of Cardiology/American Heart Association task force on practice guidelines. J Am Coll Cardiol. 2014;63(25 Pt B):2889–2934
  2. Sarwar N, Danesh J, Eiriksdottir G, et al. Triglycerides and the risk of coronary heart disease: 10,158 incident cases among 262,525 participants in 29 Western prospective studies. Circulation. 2007;115(4): 450–458.
  3. Hokanson JE, Austin MA. Plasma triglyceride level is a risk factor for cardiovascular disease independent of high-density lipoprotein cholesterol level: a meta-analysis of population-based prospective studies. J Cardiovasc Risk. 1996;3(2):213–219.
  4. Toth PP, Granowitz C, Hull M, et al. High triglycerides are associated with increased cardiovascular events, medical costs, and resource use: a real-world administrative claims analysis of statin-treated patients with high residual cardiovascular risk. J Am Heart Assoc. 2018;7:e008740.
  5. Nichols GA, Philip S, Reynolds K, et al. Increased cardiovascular risk in hypertriglyceridemic patients with statin-controlled LDL cholesterol. J Clin Endocrinol Metab. 2018;103:3019–3027.
  6. Wong ND, Chuang J, Wong K, et al. Residual dyslipidemia among United States adults treated with lipid modifying therapy (Data from National Health and Nutrition Examination Survey 2009-2010). Am J Cardiol. 2013;112:373–379.
  7. Fan W, Philip S, Granowitz C, et al. Hypertriglyceridemia in statin-treated US adults: the National Health and Nutrition Examination Survey. J Clin Lipidol. 2019;13:100–108.
  8. Miller M, Cannon CP, Murphy SA, et al. Impact of triglyceride levels beyond low-density lipoprotein cholesterol after acute coronary syndrome in the PROVE IT-TIMI 22 trial. J Am Coll Cardiol. 2008;51:724–730.
  9. Jacobson A, Savji N, Blumenthal RS, Martin SS. American College of Cardiology Expert Analysis. Hypertriglyceridemia management according to the 2018 AHA/ACC guideline. January 11, 2019. Available at https://www.acc.org/latest-in-cardiology/articles/2019/01/11/07/39/hypertriglyceridemia-management-according-to-the-2018-aha-acc-guideline.
  10. Bhatt DL, Steg PG, Miller M, et al. Cardiovascular risk reduction with icosapent ethyl for hypertriglyceridemia. N Engl J Med. 2019;380:11–22.
  11. Nicholls SJ, Lincoff AM, Bash D, et al. Assessment of omega-3 carboxylic acids in statin-treated patients with high levels of triglycerides and low levels of high-density lipoprotein cholesterol: rationale and design of the STRENGTH trial. Clin Cardiol. 2018;41:1281–1288.
  12. Pradhan AD, Paynter NP, Everett BM, et al. Rationale and design of the Pemafibrate to Reduce Cardiovascular Outcomes by Reducing Triglycerides in Patients with Diabetes (PROMINENT) study. Am Heart J. 2018;206:80–93.

 

 

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More Evidence that Low-density Lipoprotein Cholesterol and Triglyceride-lowering Genetic Variants Reduce Risk of Coronary Heart Disease

More Evidence that Low-density Lipoprotein Cholesterol and Triglyceride-lowering Genetic Variants Reduce Risk of Coronary Heart Disease

By Kevin C Maki, PhD and Mary R Dicklin, PhD

 

The total cholesterol concentration in circulation is comprised of cholesterol carried by three main types of lipoproteins:  low-density lipoproteins (LDL), very-low-density lipoproteins (VLDL) and high-density lipoproteins (HDL).  VLDL particles are the main carriers of triglycerides (TG), and the Friedewald equation estimates the VLDL cholesterol (VLDL-C) level in mg/dL as TG/5.  LDL and VLDL particles each contain a single molecule of apolipoprotein B (Apo B).  Non-HDL cholesterol (non-HDL-C) is the sum of the cholesterol carried by all particles that contain Apo B, i.e., LDL-C + VLDL-C.  Note for purists:  this ignores a quantitatively small contribution of cholesterol carried by chylomicron remnants and it includes cholesterol carried by lipoprotein (a) particles, which are generally in the LDL density range.

 

Non-HDL-C has been found to be a more consistent predictor of coronary heart disease (CHD) risk than LDL-C (Liu 2005, Robinson 2009).  Prior studies have shown that genetic variants that modify each of the components of non-HDL-C are associated with modification of cardiovascular disease risk, particularly incidence of CHD.

 

Ference and colleagues recently published a large-scale analysis of data from a group of 654,783 subjects, in 63 case-control or cohort studies, to investigate two sets of lipid-lowering genetic variants for the LDL receptor gene and the lipoprotein lipase (LPL) gene that predominantly affect LDL-C and TG, respectively (Ference 2019, Navar 2019).  The analysis included 91,129 cases of CHD.  Their investigation showed that both genetically-induced LDL-C reduction through the LDL receptor gene score and TG reduction through the LPL gene score were associated with significantly reduced CHD risk, findings which agree with those from prior investigations.

 

The authors then extended their analysis by investigating 168 genetic variants associated with either LDL-C or TG modification.  In order to make an “apples to apples” comparison, the associations were standardized to a 10 mg/dL difference in genetically-induced LDL-C reduction and a 50 mg/dL reduction in TG, which is equivalent to a 10 mg/dL reduction in VLDL-C (TG/5 = VLDL-C).  Each 10 mg/dL reduction in LDL-C was associated with 15.4% lower odds for CHD (odds ratio = 0.846) and each 10 mg/dL reduction in VLDL-C (50 mg/dL reduction in TG) was associated with 18.5% lower odds for CHD (odds ratio = 0.815).

 

Since LDL and VLDL particles each contain Apo B, the authors also investigated the effects of a 10 mg/dL genetically-induced reduction in Apo B.  The resulting odds ratio was 0.770, indicating 23% lower odds for CHD.  When 10 mg/dL reductions in all three (LDL-C, VLDL-C and Apo B) were included in the same model, only Apo B remained significant (odds ratio = 0.761). 

 

Comment on clinical implications.  The Apo B concentration represents the total number of circulating particles with atherogenic potential.  Most investigations have shown that Apo B predicts CHD risk slightly better than non-HDL-C, which is, in turn, a better predictor than LDL-C.  The present study extends those findings by showing that genetic modification of Apo B concentration is strongly associated with CHD risk, supporting a causal relationship.  The non-HDL-C concentration correlates strongly with the Apo B level because it represents cholesterol carried by the two main types of Apo B-containing lipoproteins, LDL and VLDL.

 

The National Lipid Association’s Recommendations for Patient-centered Management of Dyslipidemia identified non-HDL-C and LDL-C as co-primary targets of therapy for lipid modification (Jacobson 2014).  The recent American Heart Association/American College of Cardiology Guideline on the Management of Blood Cholesterol (Grundy 2018) also acknowledges the importance of non-HDL-C by identifying thresholds for either LDL-C or non-HDL-C for consideration of adding adjunctive therapy to a statin as a way of identifying patients who could potentially benefit from additional Apo B-containing lipoprotein reduction.  The results from this new study by Ference and colleagues suggest that a 10 mg/dL decline in VLDL-C has similar predictive value to that of a 10 mg/dL decline in LDL-C and that the predictive value of each is contained within the Apo B concentration.

 

In the US, Apo B measurement is not commonly completed.  Since non-HDL-C correlates strongly with the Apo B concentration, it can serve as a reasonable surrogate.  The National Lipid Association recommendations suggest goals for LDL-C of <70 mg/dL for those at very high risk and <100 mg/dL for others (Jacobson 2014).  The corresponding goals for non-HDL-C are <100 and <130 mg/dL, respectively.  It should be emphasized that the relationships show no evidence of thresholds, so reductions to levels of LDL-C and non-HDL-C well below 70 and 100 mg/dL, respectively, may be justified for some of the highest risk patients.  Such an approach is supported by results from studies of adjunctive therapies, including those with proprotein convertase subtilisin kexin type 9 (PCSK9) inhibitors and ezetimibe. 

 

Another important point with clinical relevance is that the reduction in CHD (or cardiovascular disease) risk with genetic variants is consistently larger than that observed in clinical trials of lipid-altering therapies.  For example, in a Cholesterol Treatment Trialists’ Collaboration analysis (2010), each mmol/L (38.7 mg/dL) reduction in LDL-C was associated with a 24% reduction in major CHD event risk, which means that a 10 mg/dL reduction induced by statin therapy would reduce CHD event risk by 6.8% (1 – 0.76(10/38.7) = 0.068 or 6.8%), considerably less than the 15.4% lower odds for CHD in the Ference investigation.  This likely reflects the greater length of time that individuals with genetic variants are exposed to altered levels of lipoproteins.  The implication is that even modestly lower levels of LDL-C and VLDL-C can have important impacts on CHD risk if maintained over an extended period, which highlights the importance of healthy diet and adequate physical activity.

 

The recently published results from the Reduction of Cardiovascular Events with EPA – Intervention Trial (REDUCE-IT) with eicosapentaenoic acid (EPA) ethyl esters showed an impressive reduction of 25% for major adverse cardiovascular events in patients with low baseline LDL-C (median 74 mg/dL) and elevated TG (median 216 mg/dL) (Bhatt 2019).  The placebo-corrected reductions in non-HDL-C and Apo B in the active treatment group were 10 mg/dL and 5-8 mg/dL, respectively.  The cardiovascular disease benefit was much larger than would be predicted based on the observed effects on non-HDL-C and Apo B over a period of ~5 years.  Similarly, studies of other TG-lowering drug therapies such as fibrates have shown substantial reductions in risk among subsets of patients with elevated TG, especially if accompanied by low HDL-C (Sacks 2010, Maki 2016).  In a meta-analysis completed by our group, cardiovascular disease risk reductions were 18% and 29% in studies of TG-lowering therapies in subgroups with elevated TG and elevated TG plus low HDL-C, respectively (Maki 2016).  It appears unlikely that these results can be explained entirely by changes in non-HDL-C or Apo B levels.  Therefore, additional research is needed to investigate pathways through which TG-lowering therapies affect cardiovascular risk.

 

In summary, genetically-induced reduction in LDL-C and VLDL-C (estimated as TG/5) are each associated with similar reductions in CHD risk.  The predictive value of each of these is contained within Apo B.  Since Apo B concentration is rarely measured in the US, non-HDL-C can serve as a surrogate marker and is a preferable target of therapy to LDL-C, because changes in both components of non-HDL-C (LDL-C and VLDL-C) appear to contribute similarly to risk alteration when compared on an “apples to apples” basis.  Thus, a 50 mg/dL reduction in TG (equivalent to a 10 mg/dL reduction in VLDL-C) should be expected to produce the same benefit for CHD risk as a 10 mg/dL lowering of LDL-C.

 

References

Bhatt DL, Steg PG, Miller M, et al. Cardiovascular risk reduction with icosapent ethyl for hypertriglyceridemia. N Engl J Med. 2019;380:11-22.

Cholesterol Treatment Trialists’ (CTT) Collaboration, Baigent C, Blackwell L, et al. Efficacy and safety of more intensive lowering of LDL cholesterol: a meta-analysis of data from 170,000 participants in 26 randomised trials. Lancet. 2010;376:1670-1681.

Ference BA, Kastelein JJP, Ray KK, et al. Association of triglyceride-lowering LPL variants and LDL-C lowering LDLR variants with risk of coronary heart disease. JAMA. 2019;321:364-373.

Grundy SM, Stone NJ, Bailey AL, et al. 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA guideline on the management of blood cholesterol. Circulation. 2018 [Epub ahead of print].

Jacobson TA, Ito MK, Maki KC, et al. National Lipid Association recommendations for patient-centered management of dyslipidemia: part 1 – executive summary. J Clin Lipidol. 2014;8:473-488.

Liu J, Sempos C, Donahue RP, et al. Joint distribution of non-HDL and LDL cholesterol and coronary heart disease risk prediction among individuals with and without diabetes. Diabetes Care. 2005;28:1916-1921.

Maki KC, Guyton JR, Orringer CE, et al. Triglyceride-lowering therapies reduce cardiovascular disease event risk in subjects with hypertriglyceridemia. J Clin Lipidol. 2016;10:905-914.

Navar AM. The evolving story of triglycerides and coronary heart disease risk. JAMA. 321:347-349.

Robinson JG. Are you targeting non-high-density lipoprotein cholesterol? J Am Coll Cardiol. 2009;55:42-44.

Sacks FM, Carey VJ, Fruchart JC. Combination lipid therapy in type 2 diabetes. N Engl J Med. 2010;363:692-694.

Closeup of doctor checking patient daily report checklist

Recent Headlines from the Late-breaking Clinical Trial Presentations at the American Heart Association Scientific Sessions

Recent Headlines from the Late-breaking Clinical Trial Presentations at the American Heart Association Scientific Sessions -

REDUCE-IT – a Landmark Cardiovascular Outcomes Study of an Omega-3 Fatty Acid

 

By Kevin C Maki, PhD and Mary R Dicklin, PhD

 The primary results from the Reduction of Cardiovascular Events with Eicosapentaenoic Acid (EPA) – Intervention Trial (REDUCE-IT) were recently presented at the late-breaking clinical trial sessions of the American Heart Association meeting in Chicago, IL and simultaneously published in the New England Journal of Medicine.1,2  These results followed the topline result announced last month by Amarin, the maker of Vascepa® (icosapent ethyl), indicating an ~25% relative risk reduction in the primary composite endpoint of cardiovascular death, nonfatal myocardial infarction (MI), nonfatal stroke, coronary revascularization or unstable angina.3

 REDUCE-IT was a multicenter, randomized, double-blind trial that examined the effects of a high dosage of 4 g/d Vascepa providing ~3700 mg EPA vs. placebo on cardiovascular outcomes in 8179 statin-treated adults at high cardiovascular risk, followed for a median of 4.9 y.1  At entry, participants had an elevated fasting triglyceride (TG) level (median 216 mg/dL) and well-controlled low-density lipoprotein cholesterol (LDL-C; median of 75 mg/dL).  The primary endpoint occurred in 17.2% of patients on Vascepa vs. 22.0% of patients on placebo (hazard ratio [HR] 0.75, 95% confidence interval [CI] 0.68 to 0.83, p < 0.001).  The key secondary endpoint, which was a composite of cardiovascular death, nonfatal MI or nonfatal stroke, occurred in 11.2% of patients on Vascepa vs. 14.8% of patients on placebo (HR 0.74, 95% CI 0.65 to 0.83, p < 0.001).  The rates of all of the individual and composite endpoints (except for death from any cause) were all significantly lower with Vascepa than with placebo.  The overall rates of adverse events during the trial, and the rates of serious adverse events leading to discontinuation, were not significantly different between Vascepa and placebo groups.

A notable finding in REDUCE-IT was a 20% lower rate of cardiovascular death (p = 0.03).1  Our group previously conducted a meta-analysis of 14 randomized controlled trials that investigated the effects of omega-3 fatty acids on cardiac death, and found an 8% lower risk with omega-3 supplementation vs. controls.4  The effect was much larger (~29%) in studies that tested dosages >1 g/d EPA + docosahexaenoic acid (DHA).  Although REDUCE-IT did not include a coronary heart disease (CHD) death endpoint, the publication did include enough information to perform a rough calculation of it based on fatal MI, sudden cardiac death (SCD) and heart failure death.1  There were numerically lower incidence rates for both fatal MI and SCD in REDUCE-IT, but death from heart failure did not differ in the treatment arms, which suggests that the benefit to cardiovascular death was driven by fatal MI, SCD and fatal stroke, but not heart failure death.  To assess the possibility for detecting a benefit for fatal CHD with omega-3 fatty acids, we added our estimate from REDUCE-IT, to the results from a recent meta-analysis conducted by Aung et al.,5 along with data from A Study of Cardiovascular Events in Diabetes (ASCEND),6 and the recently published Vitamin D and Omega-3 Trial (VITAL).7  Doing this demonstrated a statistically significant reduction in fatal CHD with omega-3 fatty acids (details are below).

  • Aung meta-analysis5: 1301 of 39,017 participants for omega-3 and 1394 of 38,900 participants for control;
  • ASCEND6: 100 of 7740 participants for omega-3 and 127 of 7740 participants for control;
  • VITAL7: 37 of 12,933 participants for omega-3 and 49 of 12,938 participants for control;
  • REDUCE-IT (fatal MI + SCD)1: 74 of 4089 participants for omega-3 and 110 of 4090 participants for control;
  • When combined, this shows that CHD death occurred in 2.37% of 63,779 participants receiving omega-3 interventions and 2.64% of 63,668 participants in control conditions; the relative risk is 0.901 (95% CI 0.841 to 0.965, p = 0.003).

The result is also statistically significant without inclusion of the REDUCE-IT findings (relative risk 0.914, 95% CI 0.852 to 0.981, p = 0.013).  The robust results from REDUCE-IT, which included reductions in stroke as well as fatal and non-fatal CHD, suggest that low dosage in many of the prior studies was the reason for failure to demonstrate clear differences between the omega-3 and control groups in cardiovascular event rates.  Whether EPA is superior to DHA for risk reduction remains to be determined, and the results from the ongoing Outcomes Study to Assess Statin Residual Risk Reduction with Epanova® in High Risk Patients with Hypertriglyceridemia (STRENGTH), which are expected in 2019 or 2020, should provide information relevant to assessing this question.8  Epanova provides EPA + DHA in carboxylic acid (free fatty acid) form.

Some experts expressed surprise with the results from REDUCE-IT, because of the numerous unfavorable interpretations of results from other recently published trials and meta-analyses of the effects of omega-3 fatty acids on cardiovascular outcomes.5,6  While we agree that the magnitude of effect in REDUCE-IT, i.e., 25% reduction in risk, was somewhat larger than expected, as we previously expressed, in our opinion, the failure to show benefit in some of those previous studies was due to study design issues.9  Many of the prior studies tested low dosages (most administered just 1 g/d Omacor®/Lovaza® providing ~840 mg EPA + DHA), and they failed to examine the intervention in subjects with hypertriglyceridemia who would be expected to benefit most from a TG-lowering intervention.9  In another meta-analysis, our group found that medications that substantially lower TG (i.e., fibrates, niacin, omega-3 fatty acids) appeared to reduce cardiovascular disease risk in those with elevated TG, especially if accompanied by low high-density lipoprotein cholesterol (HDL-C) levels.10,11  The results from REDUCE-IT confirmed the larger benefit in those with elevated TG plus low HDL-C, with a reduction in the primary outcome of 38% in those with TG ≥200 mg/dL plus HDL-C ≤35 mg/dL, and 21% in those without this combination (p = 0.04 for interaction).

The REDUCE-IT authors suggested that at least some of the reduced risk of ischemic events may be explained by metabolic effects other than reduced TG levels.  This possibility is supported by the finding that the effect of the drug on primary and key secondary outcomes did not differ among those with and without achieved TG <150 mg/dL at one year.  There are several potential mechanisms through which EPA could lower risk beyond TG lowering, including, among others, reductions in inflammation, antiplatelet effects and plaque stabilization.  There was a statistically significant (p < 0.001) difference in high-sensitivity C-reactive protein (hs-CRP) response of 0.4 to 0.9 mg/L (21-40% depending on how calculated and timepoint) between the treatment arms favoring the active treatment group.1  Thus, it is possible, and in our view likely, that anti-inflammatory effects may have contributed to the observed benefits.

There have been concerns raised regarding some of the laboratory results in the trial.  For example, the use of the mineral oil placebo was problematic in that it was associated with increases in TG, LDL-C and non-HDL-C of 2.2%, 10.9%, and 10.4%, respectively at year 1, and apolipoprotein B and hs-CRP of 7.8% and 32.3%, respectively at 2 years.1,2  While not ideal, it is important to compare this to other clinical trials of prescription lipid-altering medications.  For example, among subjects taking placebo in the ODYSSEY Outcomes trial, there was an increase of approximately 12% in LDL-C during the treatment period (92 mg/dL to 103 mg/dL).12  Thus, it appears very unlikely that an adverse effect of the mineral oil placebo can explain more than a small fraction of the observed benefit.  In the Japan EPA Lipid Intervention Study (JELIS),13 a similar drug (1.8 g/d EPA from ethyl esters) reduced the primary cardiovascular endpoint by 19% compared with a no treatment control (not placebo).  The concordance in results between the trials provides compelling evidence that the benefit in REDUCE-IT is not artifactual.

Overall, it is our opinion that the results from REDUCE-IT are an important answer to the question of whether omega-3 fatty acids (EPA alone as icosapent ethyl in this instance) reduce cardiovascular risk when administered at a sufficiently high dosage to subjects with elevated TG who are at high cardiovascular risk.  This is unequivocally good news for patients and has been long-awaited given the large number of trials of low-dosage omega-3 fatty acids that had failed to produce clear evidence of cardiovascular benefit.  Additional trials are warranted to determine whether higher dosages of omega-3 fatty acids will also produce cardiovascular benefits in other population subgroups.

References:

  1. Bhatt DL, Steg G, Miller M, et al. Cardiovascular risk reduction with icosapent ethyl for hypertriglyceridemia. N Engl J Med. 2018; Epub ahead of print.

 

  1. Kastelein JJP, Stroes ESG. FISHing for the miracle of eicosapentaenoic acid. N Engl J Med. 2018; Epub ahead of print.

 

  1. Amarin Corporation. REDUCE-IT cardiovascular outcomes study of VASCEPA® (icosapent ethyl) capsules met primary endpoint. September 24, 2018. Available at https://investor.amarincorp.com/news-releases/news-release-details/reduce-ittm-cardiovascular-outcomes-study-vascepar-icosapent.

 

  1. Maki KC, Palacios OM, Bell M, Toth PP. Use of supplemental long-chain omega-3 fatty acids and risk for cardiac death: an updated meta-analysis and review of research gaps. J Clin Lipidol. 2018;11:1152-1160.

 

  1. Aung T, Halsey J, Kromhout D, et al. Associations of omega-3 fatty acid supplement use with cardiovascular disease risks: meta-analysis of 10 trials involving 77917 individuals. JAMA Cardiol. 2018;3:225-234.

 

  1. ASCEND Study Collaborative Group. Effects of n-3 fatty acid supplements in diabetes mellitus. N Engl J Med. 2018; Epub ahead of print.

 

  1. Manson JE, Cook NR, Lee IM, et al. Marine n-3 fatty acids and prevention of cardiovascular disease and cancer. N Engl J Med. 2018; Epub ahead of print.

 

  1. Nicholls SJ, Lincoff AM, Bash D, et al. Assessment of omega-3 carboxylic acids in statin-treated patients with high levels of triglycerides and low levels of high-density lipoprotein cholesterol: rationale and design of the STRENGTH trial. Clin Cardiol. 2018;41:1281-1288.

 

  1. Maki KC, Dicklin MR. Omega-3 fatty acid supplementation and cardiovascular disease risk: glass half full or time to nail the coffin shut? Nutrients. 2018;10(7).

 

  1. Maki JC, Guyton JR, Orringer CE, et al. Triglyceride-lowering therapies reduce cardiovascular disease event risk in subjects with hypertriglyceridemia. J Clin Lipidol. 2016;10:905-914.

 

  1. Maki KC, Dicklin MR. Do triglyceride-lowering drugs decrease risk of cardiovascular disease? Curr Opin Lipidol. 2017;28:374-379.

 

  1. Schwarz GG, Steg G, Szarek M, et al. Alirocumab and cardiovascular outcomes after acute coronary syndrome. N Engl J Med. 2018; Epub ahead of print.

 

  1. Yokoyama M, Origasa H, Matsuzaki M, et al. Effects of eicosapentaenoic acid on major coronary events in hypercholesterolaemic patients (JELIS): a randomized open-label, blinded endpoint analysis. Lancet. 2007;369:1090-1098.
Photo by Martin Brosy

Mechanisms Responsible for the Benefit on Cardiovascular Risk in the REDUCE-IT Trial

Mechanisms Responsible for the Benefit on Cardiovascular Risk in the REDUCE-IT Trial

By Kevin C Maki, PhD

 

Recently, we learned of the impressive topline results from the Reduction of Cardiovascular Events with Eicosapentaenoic Acid (EPA) – Intervention Trial (REDUCE-IT), which showed that Vascepa® (icosapent ethyl or EPA ethyl esters) lowered major adverse cardiovascular events (MACE) by nearly 25% (p < 0.001) when added to statin therapy in patients with hypertriglyceridemia at high cardiovascular risk.1  This is great news, since residual hypertriglyceridemia is common in statin-treated patients.2  Moreover, other relatively inexpensive evidence-based therapies such as ezetimibe have been shown to have only a modest effect on MACE risk (~10%) when added to statin therapy, consistent with the anticipated effect based on the degree of low-density lipoprotein cholesterol (LDL-C) lowering.  Proprotein convertase subtilisin kexin type 9 (PCSK9) inhibitors offer greater LDL-C reduction, but at a much higher cost.

 

The topline results from REDUCE-IT were a surprise to many who had concluded, based mainly on results from studies of omega-3 fatty acid interventions at low dosages in groups that did not have elevated average levels of triglycerides (TG), that omega-3 fatty acids were ineffective for lowering cardiovascular disease risk.3-7  I am looking forward to seeing the full set of results from REDUCE-IT, which will be presented at the 2018 American Heart Association Scientific Sessions and, hopefully, simultaneously published in a peer-reviewed journal.  These should provide more insight into the nature of the event reduction and possible lipid and non-lipid related drivers of the MACE reduction.

 

We know from the development program for Vascepa that it produces significant reductions in TG and TG-rich lipoprotein cholesterol levels.  In the ANCHOR trial, 4 g/d of Vascepa lowered the TG level by 21.5% relative to placebo in hypertriglyceridemic patients (median baseline TG 259 mg/dL) on statin therapy.8  In REDUCE-IT, the median baseline TG concentration was 216 mg/dL.  Therefore, if we assume a similar percentage reduction in TG, that would be 0.215 x 216 = 46.4 mg/dL.

 

There are several mechanisms through which long-chain omega-3 fatty acid interventions, (including EPA) may affect cardiovascular risk, of which TG lowering is only one.  Others include reducing myocardial fibrosis, lowering blood pressure and heart rate, reducing platelet activation and anti-inflammatory effects.9,10  Also, the physiologic effects of EPA, docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA; an intermediate in the conversion of EPA to DHA) are not identical, so we cannot assume that the effects will be identical for interventions that vary in the proportions of these fatty acids.  However, my view is that a large fraction of the benefit in REDUCE-IT is likely to be attributable to TG lowering based on two lines of evidence.

 

First, a meta-analysis conducted by my colleagues and I of the effects of TG-lowering drug therapies showed a modest effect overall (12% risk reduction in 10 trials), but larger effects in subgroups with TG ≥150 mg/dL (18% risk reduction), especially if accompanied by low high-density lipoprotein cholesterol (HDL-C; 29% risk reduction).11,12  The subjects in REDUCE-IT all had elevated TG and a large percentage likely also had low HDL-C.

 

Second, a meta-regression by Jun et al. showed that each 0.1 mmol/L (8.85 mg/dL) reduction in TG with fibrate therapy was associated with a reduction of 5% in MACE risk.13  The approximate reduction in TG relative to placebo of 46.4 mg/dL in REDUCE-IT would therefore be expected to produce 5.24 units (46.4/8.85 = 5.24) of 5% MACE reduction, i.e., 1 - 0.955.24= 0.236 or 23.6% MACE reduction.  The biologic plausibility of a benefit being attributable to TG reduction is supported not only by evidence from prior randomized, controlled trials of TG-lowering drug therapies (albeit in subgroups), but also by studies showing that genetic variants associated with reduced TG (and TG-rich lipoprotein cholesterol) are associated with lower cardiovascular risk. 

 

My colleagues and I view the results from REDUCE-IT as a major positive development for patient care.  We eagerly anticipate the full REDUCE-IT results, as well as those from additional studies that, we hope, will provide greater insight into the mechanisms responsible for reduced MACE risk in the REDUCE-IT trial.

 

References:

  1. Amarin Corporation. REDUCE-IT cardiovascular outcomes study of VASCEPA® (icosapent ethyl) capsules met primary endpoint. September 24, 2018. Available at https://investor.amarincorp.com/news-releases/news-release-details/reduce-ittm-cardiovascular-outcomes-study-vascepar-icosapent.

 

  1. Fan W, Philip S, Granowitz C, et al. Prevalence and predictors of residual hypertriglyceridemia according to statin use in US adults. J Clin Lipidol. 2018;12:530-531.

 

  1. Maki KC, Dicklin MR. Omega-3 fatty acid supplementation and cardiovascular disease risk: glass half full or time to nail the coffin shut? Nutrients. 2018;10:864.

 

  1. Aung T, Halsey J, Kromhout D, et al. Associations of omega-3 fatty acid supplement use with cardiovascular disease risks: Meta-analysis of 10 trials involving 77,917 individuals. JAMA Cardiol. 2018;3:224-234.

 

  1. Alexander DD, Miller PE, Van Elswyk ME, et al. A meta-analysis of randomized controlled trials and prospective cohort studies of eicosapentaenoic and docosahexaenoic long-chain omega-3 fatty acids and coronary heart disease risk. Mayo Clin Proc. 2017;29:15-29.

 

  1. Abdelhamid AS, Brown TJ, Brainard JS, et al. Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database Syst Rev. 2018;7:CD003177.

 

  1. The ASCEND Study Collaborative Group. Effects of n-3 fatty acid supplements in diabetes mellitus. N Engl J Med. 2018 [Epub ahead of print].

 

  1. Ballantyne CM, Bays HE, Kastelein JJ, et al. Efficacy and safety of eicosapentaenoic acid ethyl ester (AMR 101) therapy in statin-treated patients with persistent high triglycerides (from the ANCHOR study). Am J Cardiol. 2012;110:984-992.

 

  1. Mozaffarian D, Wu JH. Omega-3 fatty acids and cardiovascular disease: effects on risk factors, molecular pathways, and clinical events. J Am Coll Cardiol. 2011;58:2047-2067.

 

  1. Mozaffarian D, Prineas RJ, Stein PK, Siscovick DS. Dietary fish and n-3 fatty acid intake and cardiac electrocardiographic parameters in humans. J Am Coll Cardiol. 2006;38:478-484.

 

  1. Maki KC, Guyton JR, Orringer CE, et al. Triglyceride-lowering therapies reduce cardiovascular disease event risk in subjects with hypertriglyceridemia. J Clin Lipidol. 2016;10:905-914.

 

  1. Maki KC, Dicklin MR. Do triglyceride-lowering drugs decrease risk of cardiovascular disease? Curr Opin Lipidol. 2017;28:374-379.

 

  1. Jun M, Foote C, Lv J, et al. Effects of fibrates on cardiovascular outcomes: a systematic review and meta-analysis. Lancet. 2010;375:1875-1884.

 

 

 

Photo by Vincent Botta

Topline Results from REDUCE-IT Show a Significant Reduction in Cardiovascular Outcomes with Omega-3 Fatty Acid

Topline Results from REDUCE-IT Show a Significant Reduction in Cardiovascular Outcomes with Omega-3 Fatty Acid

By Kevin C Maki, PhD and Mary R Dicklin, PhD

 

Exciting topline results from the Reduction of Cardiovascular Events with Eicosapentaenoic Acid (EPA) – Intervention Trial (REDUCE-IT) were recently announced by Amarin, the maker of Vascepa®.1 The full results are scheduled to be presented on November 10, 2018 at the American Heart Association’s (AHA) Scientific Sessions in Chicago, IL.  REDUCE-IT was a randomized, controlled trial that examined the effects of 4 g/d Vascepa vs. placebo on cardiovascular outcomes in statin-treated adults at elevated cardiovascular risk.2   Topline results indicated an ~25% relative risk reduction (p < 0.001) in the primary composite endpoint of the first occurrence of a major adverse cardiovascular event, including cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, coronary revascularization, or unstable angina requiring hospitalization, after a median follow-up of 4.9 y.1

 

These results will take some by surprise, based on the abundance of unfavorable interpretations of the effects of omega-3 fatty acids on cardiovascular outcomes from other recently published trials and meta-analyses.3,4  However, as my colleagues and I previously speculated,5 a failure to show benefit in some of those other studies has likely been due, at least in part, to study design issues, including administration of low dosages and absence of a clear pathophysiologic target for the intervention.  Unlike previous studies, many of which gave 1 g/d Omacor®/Lovaza®, containing ~850 mg EPA + docosahexaenoic acid (DHA),6 in REDUCE-IT subjects received a high dosage of 4 g/d Vascepa (roughly 3,700 mg of EPA).Subjects in REDUCE-IT were also required to have elevated baseline triglycerides (TG) of ≥150 mg/dL and <500 mg/dL (lower limit later changed to ≥200 mg/dL), resulting in a median baseline TG level of 216 mg/dL.  Results from our meta-analysis suggested that medications which substantially lower TG reduce cardiovascular risk in those with elevated TG, especially if accompanied by low high-density-lipoprotein cholesterol.7  Thus, REDUCE-IT directly addressed the issue of TG-lowering as a target of therapy.

 

Our separate meta-analysis of 14 randomized controlled trials that investigated the effects of omega-3 fatty acids on cardiac death showed an 8% lower risk with omega-3 supplementation vs. controls, although the effect was much larger (29%) in studies where the dosage employed was >1 g/d of EPA + DHA.8  It is uncertain whether REDUCE-IT will have enough cardiac deaths to show a benefit for that outcome, although it should add a substantial number of events to the aggregate database of studies using higher dosages. 

 

Results from another large-scale clinical trial of omega-3 fatty acids, the Vitamin D and Omega-3 Trial (VITAL), are also scheduled to be presented at AHA.  In VITAL, subjects received 1 g/d of Omacor/Lovaza and were not required to have elevated TG levels at baseline.9  The results from VITAL and another recently reported trial (A Study of Cardiovascular Events in Diabetes; ASCEND)4 will facilitate a more complete assessment of the effects of low-dosage EPA + DHA on the risk of cardiac death, which has important public health implications.

 

The Outcomes Study to Assess Statin Residual Risk Reduction with Epanova in High Cardiovascular Risk Patients with Hypertriglyceridemia (STRENGTH) is another high-dosage study (4 g/d) of the carboxylic acids (free fatty acids) form of EPA + DHA, and the last of the large-scale omega-3 trials underway.  Subjects in STRENGTH were required to not only have elevated TG (≥180 mg/dL and <500 mg/dL), but also to have low levels of high-density lipoprotein cholesterol (<47 mg/dL for women and <42 mg/dL for men).10  STRENGTH is scheduled to complete in the fall of 2019.

 

References:

  1. Amarin Corporation. REDUCE-IT cardiovascular outcomes study of VASCEPA® (icosapent ethyl) capsules met primary endpoint. September 24, 2018. Available at https://investor.amarincorp.com/news-releases/news-release-details/reduce-ittm-cardiovascular-outcomes-study-vascepar-icosapent.

 

  1. Bhatt DL, Steg PG, Brinton EA, et al. Rationale and design of REDUCE-IT: reduction of cardiovascular events with icosapent ethyl-intervention trial. Clin Cardiol. 2017;40:138-148.

 

  1. Aung T, Halsey J, Kromhout D, et al. Associations of omega-3 fatty acid supplement use with cardiovascular disease risks: meta-analysis of 10 trials involving 77917 individuals. JAMA Cardiol. 2018;3:225-234.

 

  1. ASCEND Study Collaborative Group. Effects of n-3 fatty acid supplements in diabetes mellitus. N Engl J Med. 2018; Epub ahead of print.

 

  1. Maki KC, Dicklin MR. Omega-3 fatty acid supplementation and cardiovascular disease risk: glass half full or time to nail the coffin shut? Nutrients. 2018;10(7).

 

  1. Abdelhamid AS, Brown TJ, Brainard JS, et al. Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database Syst Rev. 2018;7:CD003177.

 

  1. Maki JC, Guyton JR, Orringer CE, et al. Triglyceride-lowering therapies reduce cardiovascular disease event risk in subjects with hypertriglyceridemia. J Clin Lipidol. 2016;10:905-914.

 

  1. Maki KC, Palacios OM, Bell M, Toth PP. Use of supplemental long-chain omega-3 fatty acids and risk for cardiac death: an updated meta-analysis and review of research gaps. J Clin Lipidol. 2018;11:1152-1160.

 

  1. Manson JE, Bassuk SS, Lee IM, et al. The Vitamin D and Omega-3 Trial (VITAL): rationale and design of a large randomized controlled trial of vitamin D and marine omega-3 fatty acid supplements for the primary prevention of cancer and cardiovascular disease. Contemp Clin trials. 2012;33:159-171.

 

 

  1. Nicholls SJ, Lincoff AM, Bash D, et al. Assessment of omega-3 carboxylic acids in statin-treated patients with high levels of triglycerides and low levels of high-density lipoprotein cholesterol: rationale and design of the STRENGTH trial. Clin Cardiol. 2018; Epub ahead of print.
Photo by i yunmai

A Review of Three Recently Published Papers on Dietary Approaches to Weight Loss and Fat Mobilization

A Review of Three Recently Published Papers on Dietary Approaches to Weight Loss and Fat Mobilization

By Kristen N Smith, PhD, RD; Mary R Dicklin, PhD; Kevin C Maki, PhD, CLS

 

Background:

There have been multiple papers published this year focusing on various dietary approaches for producing weight loss and their effects on weight-related outcomes, including changes in body composition and cardiovascular disease risk factors. This post will summarize three recently published original research articles.

 

  1. Low-Fat vs. Low-Carbohydrate and Weight-Loss Diets (DIETFITS)1:

It is well-established that obesity is a major public health challenge and that dietary modifications are essential for successful weight loss. Commonly investigated approaches include diets that restrict intake of fat or carbohydrate2-4. No matter what macronutrient is emphasized or restricted, most trials have reported modest (~ 5% or less) mean weight loss after 12 months, with negligible differences between the different diet groups.5 However, when assessing weight-loss outcomes of individual subjects, these have varied widely within diet groups and ranged from weight loss of ~25 kg (~55 lbs) to weight gain of ~5 kg (11 lbs).2-4 There appears to be no one specific dietary strategy that is consistently superior for weight management within the general population. Additionally, results from some prior studies have suggested that an individual’s genotype or insulin-glucose dynamics may have an impact on the outcomes associated with certain diets. For example, it has been hypothesized that individuals with higher insulin resistance or insulin secretion may respond more favorably to a low-carbohydrate dietary regimen.6

 

The objective of the Diet Intervention Examining the Factors Interacting with Treatment Success (DIETFITS) trial was to assess the effect of a healthy low-fat (HLF) diet vs. a healthy low-carbohydrate (HLC) diet on weight change and to examine whether genotype pattern or insulin secretion are related to dietary effects on weight loss. This study was a single-site, parallel-group, weight-loss trial that randomized individuals to either a HLF diet or a HLC diet for 12 months. Subjects (N = 609) were men and premenopausal women aged 18 to 50 y with body mass index (BMI) 28 to 40 kg/m2. The study began with a 1-month run-in during which subjects were instructed to maintain their habitual diet, physical activity and body weight. Throughout the study period, registered dietitian health educators led 22 diet-specific instructional sessions guiding the participants to follow their assigned plan. The researchers also investigated whether three single-nucleotide polymorphism multi-locus genotype patterns or insulin secretion (blood concentration of insulin 30 min after a glucose challenge) were associated with weight loss.

 

Primary Outcome

Secondary Outcomes

§  12-month weight change

§  Other anthropometric measures (BMI, % body fat, waist circumference)

§  Plasma lipids

§  Plasma insulin and glucose (fasting and after a glucose challenge)

§  Blood pressure

 

Subject characteristics:

  • Mean (standard deviation) age: 40 (7) y,
  • 57% women,
  • Mean (standard deviation) BMI: 33 (3) kg/m2,
  • Mean baseline blood concentration of insulin 30 min after glucose challenge 93 µU/mL,
  • 481 (79%) completed the trial.

 

Weight change at 12 months did not vary between the two diet groups (-5.3 kg for HLF vs -6.0 kg for HLC; mean between-group difference, 0.7 kg 95% confidence interval, -0.2 to 1.6 kg). There were no significant diet x genotype (p = 0.20) or diet x insulin secretion interactions (p = 0.47). Overall, both diets produced a mean weight loss of ~6 kg over 12 months, but no new knowledge was gained regarding how to identify which diet would be better suited for whom.

 

  1. Vegetarian vs. Mediterranean Diet and Cardiovascular Disease Risk (CARDIVEG)7:

A lacto-ovo vegetarian diet (VD) is the most common type of vegetarian diet. It excludes meat, fish and poultry in all forms, but allows intake of eggs and dairy products.8 A 2017 meta-analysis of >130,000 vegetarians found that adherence to a VD was associated with many favorable health characteristics, including lower levels of cardiovascular disease risk factors and reduced risk for ischemic heart disease.9 The potential health benefits associated with a VD may require additional investigation for several reasons: most of the studies on VD were 1) observational, 2) conducted in countries at high risk for cardiovascular disease (like the United States), 3) conducted in people who were already vegetarians. These are possible sources of bias because populations already following vegetarian patterns may be more health conscious and not fully representative of the overall population.10 Consequently, additional investigation of healthy VD and omnivorous patterns is warranted.

 

The aim of the Cardiovascular Prevention with Vegetarian Diet (CARDIVEG) study was to compare, in an omnivorous, low-cardiovascular-risk European population, the effects of a 3-month period on a VD versus a low-calorie Mediterranean diet (MedD) on markers of cardiovascular disease risk.11 It is important to note that the MedD is often reported as one of the healthiest models for preventing cardiovascular disease.12  The study was a randomized, open, crossover trial with 2 intervention periods of VD or MedD, each lasting 3 months, after an initial 2-week run-in period to assess participants’ motivation, commitment and availability.11 Participants underwent face-to-face, individual counseling sessions where they also received 1-week menu plans. Both interventions were low-calorie in nature and aimed at reducing body weight and risk factors for cardiovascular disease.

 

Both diet plans consisted of ~50-55% energy from carbohydrate, ~25-30% energy from total fat (≤7% energy from saturated fat, <200 mg cholesterol), and ~15-20% energy from protein. The VD was characterized by abstinence from consumption of meat and meat products, poultry, fish and seafood, and the flesh of any other animal, but it included eggs and dairy products and all other food groups. The MedD was characterized by consumption of all food groups, including meat and meat products, poultry and fish.

 

Primary Outcomes

Secondary Outcomes

Changes from baseline in:

§  Total body weight

§  BMI

§  Fat mass

Changes from baseline in:

§  Circulating cardiovascular risk parameters

o   Lipid profile

o   Glycemic profile

o   Oxidative stress profile

o   Inflammatory profile

 

Of the 118 subjects randomized, 104 completed the VD period and 103 completed the MedD period. No differences were observed between the two diets in body weight. Similar outcomes were also reported for BMI and fat mass. However, responses in laboratory outcomes including low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), vitamin B12 and uric acid levels varied. The VD significantly produced significantly larger reductions in LDL-C, vitamin B12 and uric acid levels, whereas the MedD led to a significantly greater reduction in TG levels.

 

The authors concluded that both low-calorie diets contributed to weight loss to a similar degree and cardiovascular risk factor levels at the end of the two diet periods were similar, although LDL-C was slightly lower during the VD period and TG was slightly lower during the MedD period. These results provide further evidence that both the VD and MedD are useful options for weight loss and managing the cardiovascular risk factor profile.

 

  1. Lifestyle and Diet Strategies and Fat Mobilization (CENTRAL)13

Visceral adipose tissue (VAT) is the most strongly implicated fat storage pool connecting obesity to cardiometabolic disease risk. This may be attributed to the propensity of abdominal fat to activate obesity-related stress-sensing pathways14 and release secretory products and free fatty acids into the portal vein.15

 

Results from prior studies have been controversial regarding whether specific interventions can preferentially reduce VAT.16-20 Some studies have shown that dietary interventions did not preferentially impact abdominal fat depots,18,19 whereas others in both humans and in animal models suggest dietary changes might impact VAT, with higher intakes of simple sugars and trans fatty acids being associated with increased VAT, and higher intakes of unsaturated fatty acids associated with reductions in VAT. It is unclear whether lifestyle patterns and interventions can impact losses in specific fat depots (e.g., abdominal, pericardial, and renal sinus) and deposits (e.g., hepatic, intermuscular, and pancreatic), thus producing differential effects on the cardiometabolic risk factor profile.21 The objective of the CENTRAL trial was to test the hypothesis that, beyond long-term moderate weight loss, it is possible to induce differential mobilization of VAT and other specific fat depots by lifestyle interventions, and to link the changes to specific clinical biomarkers.

 

This was an 18-month randomized controlled trial of 278 sedentary men and women with abdominal obesity or dyslipidemia. Subjects were randomly assigned to either a low-fat (LF) diet or a Mediterranean/low-carbohydrate (MED/LC) diet. Both diets were designed for moderate, long-term weight loss and restricted intakes of refined carbohydrates and trans fats, and to have increased vegetable intakes. The LF diet had <30% of calories from total fat, ≤10% of calories from saturated fat and ≤200 mg/d cholesterol. The MED/LC diet had <40 g/d carbohydrate intake in the first 2 months, gradually increased to ≤70 g/d, and increased protein and fat intakes (rich in vegetables and legumes and low in red meat). Lunch was provided daily in a workplace cafeteria, and subjects received nutritional counseling periodically throughout the study. After 6 months of dietary intervention, each group was further randomized into added moderate physical activity (PA; 80% aerobic; supervised/free gym membership) or no added PA groups.

 

Primary Outcomes

Secondary Outcomes and Biomarker Measurements

§  Body fat redistribution (VAT)

§  Dynamics of different fat depots:

o   Deep and superficial subcutaneous

o   Liver

o   Pericardial

o   Muscle

o   Pancreas

o   Renal sinus

§  Lipid profile

§  Glycemic profile

§  Leptin

§  C-reactive protein

 

Although final weight loss was not different between dietary interventions, exercise reduced waist circumference with the greatest impact in the MED/LC/PA+ group (p<0.05). VAT (-22%), intrahepatic (-29%), and intrapericardial (-11%) fat reductions from baseline were greater than pancreatic and intramuscular fat declines. PA with either dietary intervention contributed to a significantly greater loss in VAT (mean of difference, -6.67 cm2; 95% CI, -14.8 to -0.45) compared with no PA. The MED/LC diet yielded greater reductions in intrahepatic, intrapericardial, and pancreatic fats (p<0.05 for all) compared with the LF diet. Renal sinus and femoral intramuscular fats were not preferentially impacted by one diet vs. the other.

 

The study outcomes described support dietary and PA interventions for weight loss as the goal.  It also appears that the MED/LC diet pattern was more effective than a LF diet for reducing storage of intrahepatic, intrapericardial and pancreatic fat, which may have long-term implications for effects on the cardiometabolic risk factor profile, although this needs to be verified. PA, regardless of diet, independently contributed to VAT loss.

 

Although both diets produced similar moderate weight loss, the MED/LC diet resulted in greater improvements in certain cardiometabolic risk factors, including greater reductions in waist circumference, TG and TG/high-density lipoprotein cholesterol ratio and increased high-density lipoprotein cholesterol. These changes remained significant after adjusting for weight loss.

 

Commentary:

No significant differences were noted in weight loss between the dietary interventions in the three studies reviewed, although some differences were noted in the effects of the different types of diets on cardiometabolic risk factors. It is no surprise that incorporating PA into the weight loss regimen enhanced reductions in VAT and intrahepatic fat. The take-away message seems to be that energy restricted low-fat, low-carbohydrate, or Mediterranean-style diet patterns can all be effective for promoting weight/fat loss and improving the cardiometabolic risk factor profile. Individual responses and personal preferences vary widely, and those attempting to lose weight and body fat can be reassured that it is acceptable to employ any of the energy restricted dietary patterns studied in these trials, particularly when combined with sufficient PA.

 

References:

  1. Gardner CD, Trepanowski JF, Del Gobbo LC, et al. Effect of low-fat vs low-carbohydrate diet on 12-month weight loss in overweight adults and the association with genotype pattern or insulin secretion: The DIETFITS randomized clinical trial. JAMA. 2018;319(7):667-679.
  2. Gardner CD, Kiazand A, Alhassan S, et al. Comparison of the Atkins, Zone, Ornish, and LEARN diets for change in weight and related risk factors among overweight premenopausal women: the A TO Z Weight Loss Study: a randomized trial. JAMA. 2007;297(9):969-977.
  3. Sacks FM, Bray GA, Carey VJ, et al. Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. N Engl J Med. 2009;360(9):859-873.
  4. Shai I, Schwarzfuchs D, Henkin Y, et al. Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. N Engl J Med. 2008;359(3):229-241.
  5. Johnston BC, Kanters S, Bandayrel K, et al. Comparison of weight loss among named diet programs in overweight and obese adults: a meta-analysis. JAMA. 2014;312(9):923-933.
  6. Fleming JA, Kris-Etherton PM. Macronutrient content of the diet: What do we know about energy balanace and weight maintenance. Curr Obes Rep. 2015;5(2):208-213.
  7. Sofi F, Dinu M, Pagliai G, et al. Low-calorie vegetarian versus mediterranean diets for reducing body weight and improving cardiovascular risk profile: CARDIVEG Study (Cardiovascular Prevention With Vegetarian Diet). Circulation. 2018;137(11):1103-1113.
  8. Leitzmann C. Vegetarian nutrition: past, present, future. Am J Clin Nutr. 2014;100 Suppl 1:496S-502S.
  9. Dinu M, Abbate R, Gensini GF, Casini A, Sofi F. Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies. Crit Rev Food Sci Nutr. 2017;57(17):3640-3649.
  10. Kwok CS, Umar S, Myint PK, Mamas MA, Loke YK. Vegetarian diet, Seventh Day Adventists and risk of cardiovascular mortality: a systematic review and meta-analysis. Int J Cardiol. 2014;176(3):680-686.
  11. Dinu M, Pagliai G, Casini A, Sofi F. Mediterranean diet and multiple health outcomes: an umbrella review of meta-analyses of observational studies and randomised trials. Eur J Clin Nutr. 2018;72(1):30-43.
  12. Sofi F, Dinu M, Pagliai G, Cesari F, Marcucci R, Casini A. Mediterranean versus vegetarian diet for cardiovascular disease prevention (the CARDIVEG study): study protocol for a randomized controlled trial. Trials. 2016;17(1):233.
  13. Gepner Y, Shelef I, Schwarzfuchs D, et al. Effect of distinct lifestyle interventions on mobilization of fat storage pools: CENTRAL Magnetic Resonance Imaging Randomized Controlled Trial. Circulation. 2018;137(11):1143-1157.
  14. Rudich A, Kanety H, Bashan N. Adipose stress-sensing kinases: linking obesity to malfunction. Trends Endocrinol Metab. 2007;18(8):291-299.
  15. Item F, Konrad D. Visceral fat and metabolic inflammation: the portal theory revisited. Obes Rev. 2012;13 Suppl 2:30-39.
  16. Rosqvist F, Iggman D, Kullberg J, et al. Overfeeding polyunsaturated and saturated fat causes distinct effects on liver and visceral fat accumulation in humans. Diabetes. 2014;63(7):2356-2368.
  17. Maersk M, Belza A, Stodkilde-Jorgensen H, et al. Sucrose-sweetened beverages increase fat storage in the liver, muscle, and visceral fat depot: a 6-mo randomized intervention study. Am J Clin Nutr. 2012;95(2):283-289.
  18. Bray GA, Smith SR, de Jonge L, et al. Effect of dietary protein content on weight gain, energy expenditure, and body composition during overeating: a randomized controlled trial. JAMA. 2012;307(1):47-55.
  19. Haufe S, Engeli S, Kast P, et al. Randomized comparison of reduced fat and reduced carbohydrate hypocaloric diets on intrahepatic fat in overweight and obese human subjects. Hepatology. 2011;53(5):1504-1514.
  20. Rokling-Andersen MH, Rustan AC, Wensaas AJ, et al. Marine n-3 fatty acids promote size reduction of visceral adipose depots, without altering body weight and composition, in male Wistar rats fed a high-fat diet. Br J Nutr. 2009;102(7):995-1006.
  21. Tchernof A, Despres JP. Pathophysiology of human visceral obesity: an update. Physiol Rev. 2013;93(1):359-404.

 

Photo by Joel Filipe

Summary of Results from a Trial of a Novel Selective PPARɑ Modulator, Pemafibrate, on Lipid and Glucose Metabolism in Patients with Type 2 Diabetes and Hypertriglyceridemia1

Summary of Results from a Trial of a Novel Selective PPARɑ Modulator, Pemafibrate, on Lipid and Glucose Metabolism in Patients with Type 2 Diabetes and Hypertriglyceridemia

By Kristen N Smith, PhD, RD, LD; Mary R Dicklin, PhD; Kevin C Maki, PhD

 Background:

Atherosclerotic cardiovascular disease (ASCVD) is a leading cause of death in persons with type 2 diabetes2 and the incidence of cardiovascular events is elevated in patients with type 2 diabetes compared with those without diabetes.3,4 Abnormalities in lipid metabolism often accompany type 2 diabetes mellitus and are associated with insulin resistance, including:

  • Elevated triglyceride (TG) levels with delayed clearance of TG-rich lipoproteins from the circulation;
  • Reduced high-density lipoprotein cholesterol (HDL-C) levels;
  • An increased proportion of small, dense low-density lipoprotein (LDL) particles.

Several large-scale clinical trials, including the Collaborative Atorvastatin Diabetes Study (CARDS) and a Cholesterol Treatment Trialists’ (CTT) meta-analysis, have shown that effective management of dyslipidemia through LDL cholesterol (LDL-C)-lowering therapy with statins results in reduced cardiovascular risk in patients with diabetes.5,6 Other studies in people with diabetes have also identified risk factors for developing coronary heart disease including the Japan Diabetes Complication Study (JDCS), which noted high LDL-C and TG levels as risk factors, and the UK Prospective Diabetes Study (UKPDS), which showed that high LDL-C and low HDL-C are associated with elevated cardiovascular disease risk.7,8

Studies with fibrates have shown the expected decreases in TG and increases in HDL-C, but have shown inconsistent results regarding reductions in ASCVD risk in patients with type 2 diabetes. A meta-analysis completed by our group9 showed evidence that fibrates and other drugs that primarily lower TG and TG-rich lipoproteins (omega-3 fatty acid concentrates and niacin) reduce ASCVD events in participants with elevated TG, particularly if also accompanied by low HDL-C.

Pemafibrate (K-877) is a novel selective peroxisome proliferator-activated receptor alpha (PPARɑ) modulator approved for the treatment of dyslipidemia.10 Ishibashi et al. performed a dose-finding phase 2 trial of pemafibrate in patients with atherogenic dyslipidemia (elevated TG and low HDL-C) and noted significant reductions in TG and increases in HDL-C with rates of adverse events (AEs) similar to placebo. Because type 2 diabetes and atherogenic dyslipidemia often coexist, many of the patients who receive treatment with pemafibrate (once approved for marketing) are expected to also have type 2 diabetes. This summary reports on the initial 24-week treatment period for a Phase III clinical trial comparing the effects of pemafibrate and placebo in patients with elevated TG and type 2 diabetes. The primary end point of the study was the percentage change in fasting serum TG level from baseline to the end point of 24 weeks. Secondary endpoints included the percentage changes or changes from baseline in fasting and postprandial lipid-related and glycemic parameters. The primary safety end points were the incidence rates of AEs and adverse drug reactions after the study drug usage.

 Methods:

This was a multicenter, placebo-controlled, randomized, double-blind, parallel group study that was completed in 34 medical institutions in Japan from February 20, 2014 through April 30, 2015. Subjects were eligible for the study if they met the following criteria:

  • Men and postmenopausal women age ≥20 years;
  • Type 2 diabetes with glycated hemoglobin (HbA1c) ≥6.2% and TG ≥150 mg/dL (1.7 mmol/L);
  • ≥12 weeks of dietary or exercise guidance before the first screening visit.

This study included participants who were randomly assigned to receive twice daily placebo (n = 57), 0.2 mg/day pemafibrate (n = 54), or 0.4 mg/day pemafibrate (n = 55) for 24 weeks. Pemafibrate is available in 0.1 mg tablets.

 Results:

Fasting serum TG significantly decreased by ~45% with pemafibrate compared with placebo (p<0.001, see table).

 

 

Fasting TG, mg/dL, mean ± standard deviation

 

Baseline

Week 24

Placebo

  284.3 ± 117.6

240.0 ± 92.2

0.2 mg/day pemafibrate

240.3 ± 93.5

129.0 ± 71.5

0.4 mg/day pemafibrate

260.4 ± 95.9

135.8 ± 71.2

Percentage changes in fasting serum TG levels from baseline to 24 weeks were -10.8% (p < 0.01), -44.3% (p < 0.001) and -45.1% (p <0.001) for placebo, 0.2 mg/day and 0.4 mg/day, respectively. The pemafibrate groups also had significantly reduced levels of non-HDL-C, remnant lipoprotein cholesterol, apolipoprotein (Apo) B100, Apo B48 and Apo C3, and significantly increased HDL-C and Apo A1 levels. LDL-C was not significantly affected by treatment with pemafibrate. The 0.2 mg/day pemafibrate group had significant reductions in homeostasis model assessment (HOMA)-insulin resistance scores compared with placebo, but no significant alterations vs. placebo were seen in fasting plasma glucose, fasting insulin, glycoalbumin or HbA1c. Rates of AEs and adverse drug reactions were similar between the two pemafibrate groups and the placebo group.

 Comment:

This is the first report of long-term (24 weeks) efficacy and safety of pemafibrate in subjects with type 2 diabetes and hypertriglyceridemia. In this study, which was conducted in Japan, pemafibrate lowered TG levels by ~45%, which was apparent within the first month of the treatment period and maintained over the entire treatment period. An ASCVD event trial with pemafibrate commenced enrollment in 2017, the Pemafibrate to Reduce Cardiovascular Outcomes by Reducing Triglycerides in Patients with Diabetes (PROMINENT) trial, and is expected to complete in 2022 (https://clinicaltrials.gov/ct2/show/NCT03071692).

References:

  1. Araki E, Yamashita S, Arai H, et al. Effects of pemafibrate, a novel selective PPARalpha modulator, on lipid and glucose metabolism in patients with type 2 diabetes and hypertriglyceridemia: A Randomized, Double-Blind, Placebo-Controlled, Phase 3 Trial. Diabetes Care. 2018;41(3):538-546.
  2. Tancredi M, Rosengren A, Svensson AM, et al. Excess mortality among persons with type 2 diabetes. N Engl J Med. 2015;373(18):1720-1732.
  3. Haffner SM, Lehto S, Ronnemaa T, Pyorala K, Laakso M. Mortality from coronary heart disease in subjects with type 2 diabetes and in nondiabetic subjects with and without prior myocardial infarction. N Engl J Med. 1998;339(4):229-234.
  4. Mulnier HE, Seaman HE, Raleigh VS, et al. Risk of myocardial infarction in men and women with type 2 diabetes in the UK: a cohort study using the General Practice Research Database. Diabetologia. 2008;51(9):1639-1645.
  5. Colhoun HM, Betteridge DJ, Durrington PN, et al. Primary prevention of cardiovascular disease with atorvastatin in type 2 diabetes in the Collaborative Atorvastatin Diabetes Study (CARDS): multicentre randomised placebo-controlled trial. Lancet. 2004;364(9435):685-696.
  6. Cholesterol Treatment Trialists C, Kearney PM, Blackwell L, et al. Efficacy of cholesterol-lowering therapy in 18,686 people with diabetes in 14 randomised trials of statins: a meta-analysis. Lancet. 2008;371(9607):117-125.
  7. Sone H, Tanaka S, Tanaka S, et al. Serum level of triglycerides is a potent risk factor comparable to LDL cholesterol for coronary heart disease in Japanese patients with type 2 diabetes: subanalysis of the Japan Diabetes Complications Study (JDCS). J Clin Endocrinol Metab. 2011;96(11):3448-3456.
  8. Turner RC, Millns H, Neil HA, et al. Risk factors for coronary artery disease in non-insulin dependent diabetes mellitus: United Kingdom Prospective Diabetes Study (UKPDS: 23). BMJ. 1998;316(7134):823-828.
  9. Maki KC, Guyton JR, Orringer CE, Hamilton-Craig I, Alexander DD, Davidson MH. Triglyceride-lowering therapies reduce cardiovascular disease event risk in subjects with hypertriglyceridemia. J Clin Lipidol. 2016;10(4):905-914.

10.       Ishibashi S, Yamashita S, Arai H, et al. Effects of K-877, a novel selective PPARalpha modulator (SPPARMalpha), in dyslipidaemic patients: A randomized, double blind, active- and placebo-controlled, phase 2 trial. Atherosclerosis. 2016;249:36-43.

female scientist

Mendelian Randomization – Nature’s Clinical Trial – is Providing New Insights About the Causes and Potential Treatments for Cardiometabolic Diseases

Mendelian Randomization

Mendelian Randomization – Nature’s Clinical Trial – is Providing New Insights About the Causes and Potential Treatments for Cardiometabolic Diseases

By Kevin C. Maki, PhD

In a recent issue of JAMA Cardiology, Lyall and colleagues1 report that a score based on 97 genetic variants related to body mass index (BMI) was associated with increased risks for hypertension [odds ratio (OR) per 1-SD higher genetically-driven BMI of 1.64, 95% confidence interval (CI) 1.48-1.83], type 2 diabetes mellitus (OR 2.53; 95% CI 2.04-3.13) and coronary heart disease (CHD; OR 1.35; 95% CI 1.09-1.69).  Notably, the genetic BMI score was not associated with stroke risk.

Because the genetic score provides a measure of exposure over a lifetime to genetic variants that increase BMI, it is a relatively unconfounded marker that is less likely to be influenced by reverse causality than BMI itself.  Genotypes are assigned randomly when passed from parents to offspring during meiosis.2 The population genotype distribution should therefore be unrelated to the distribution of confounding variables.2  Accordingly, Mendelian randomization can be thought of as experiments of nature, similar to what is accomplished through randomization in a clinical trial.  The new results from Lyall et al.1 add evidence to support a causal relationship between increased BMI and cardiometabolic diseases.

Results reported in another recent paper by Dale and colleagues3 using Mendelian randomization also suggest causal roles for abdominal (waist-hip ratio adjusted for BMI; WHRadjBMI) and total adiposity (BMI) regarding risks for CHD and type 2 diabetes mellitus.  Each 1-SD higher WHRadjBMI (about 0.08 U) was associated with an excess risk of CHD (OR 1.48; 95% CI 1.28-1.71), similar to findings for BMI (SD about 4.6 kg/m2; OR 1.36; 95% CI, 1.22-1.52). WHRadjBMI, but not BMI, was associated with higher risk of ischemic stroke (OR 1.32; 95% CI, 1.03-1.70).  For type 2 diabetes mellitus, both variables had significant associations: OR 1.82 (95% CI 1.38-2.42) per 1-SD higher WHRadjBMI and OR 1.98 (95% CI 1.41-2.78) per 1-SD higher BMI.  These results are consistent with those reported by Lyall et al.1

Prior studies using Mendelian randomization have provided evidence for and against causality for several potentially modifiable risk factors for cardiometabolic diseases.  Evidence for causality has been provided for various lipoprotein-related variables and risks for atherosclerotic cardiovascular disease, including:4

  • Low-density lipoprotein cholesterol;
  • Triglycerides and triglyceride-rich lipoprotein cholesterol;
  • Lipoprotein (a).

Evidence against direct causality has been produced through Mendelian randomization for:4

  • High-density lipoprotein cholesterol;
  • C-reactive protein.

However, it should be noted that for high-density lipoprotein cholesterol and C-reactive protein, lack of association should not be interpreted to mean that these are not important risk indicators, only that the levels of these variables likely reflect other processes that are more directly involved in causal pathways.

The real promise of Mendelian randomization is to identify novel, modifiable targets for which new therapies can be developed.  This process was nicely illustrated by the identification of proprotein convertase subtilisin kexin type 9 (PCSK9) variants as predictors of CHD risk5, which ultimately led to the development of a new class of pharmaceuticals, the PCSK9 inhibitors.6

References:

  1. Lyall DM, Celis-Morales C, Ward J, et al. Association of body mass index with cardiometabolic disease in the UK Biobank: a Mendelian randomization study. JAMA Cardiol. July 5, 2017 [Epub ahead of print].
  2. Thanassoulis G, O’Donnell CJ. Mendelian randomization: nature’s randomized trial in the post-genome era. JAMA. 2009;301:2386-2387.
  3. Dale CE, Fatemifar G, Palmer TM, et al. Causal associations of adiposity and body fat distribution with coronary heart disease, stroke subtypes, and type 2 diabetes mellitus: a Mendelian randomization study. Circulation. 2017;135:2373-2388.
  4. Lacey B, Herrington WH, Preiss D, Lewington S, Armitage J. The role of emerging risk factors in cardiovascular outcomes. Curr Atheroscler Rep. 2017;19:28.
  5. Cohen JC, Boerwinkle E, Mosley TH, Jr., Hobbs HH. Sequence variations in PCSK9, low LDL, and protection against coronary heart disease. N Engl J Med. 2006;354:1264-1272.
  6. Durairaj A, Sabates A, Nieves J, et al. Proprotein convertase subtilisin/kexin type 9 (PCSK9) and its inhibitors: a review of physiology, biology, and clinical data. Curr Treat Options Cardio Med. 2017;19:58.
Mendelian Randomization

Replacing Refined Carbohydrates with Egg Protein and Unsaturated Fatty Acids Improves Insulin Sensitivity and the Cardiometabolic Profile

Replacing Refined Carbohydrates with Egg Protein

Replacing Refined Carbohydrates with Egg Protein and Unsaturated Fatty Acids Improves Insulin Sensitivity and the Cardiometabolic Profile

Replacing Refined Carbohydrates with Egg Protein and Unsaturated Fatty Acids Improves Insulin Sensitivity and the Cardiometabolic Profile

Consuming a healthful diet and participating in an adequate amount of physical activity are key tools for managing metabolic abnormalities that can increase risk for both cardiovascular disease and type 2 diabetes mellitus.  A growing body of evidence supports the view that a diet high in refined starches and added sugars exacerbates disturbances in carbohydrate (CHO) metabolism.  Replacement of these macronutrients with protein and/or unsaturated fatty acids (UFA) may help to improve the cardiometabolic risk factor profile.  The MB Clinical Research team conducted a trial to evaluate the effects of a combination of egg protein (Epro) and UFA, substituted for refined starches and added sugars, on insulin sensitivity and other cardiometabolic health markers in adults with elevated (≥150 mg/dL) triglycerides (TG).

Participants (11 men, 14 women) with elevated TG were randomly assigned to consume test foods prepared using Epro (~8% of energy) and UFA (~8% of energy) for the Epro/UFA condition, or using refined starch and sugar (~16% of energy) for the CHO condition.  Each diet was low in saturated fat and consumed for 3 weeks in a controlled feeding (all food provided) crossover trial, with a 2-week washout between diets.  Insulin sensitivity, assessed by the Matsuda insulin sensitivity index (MISI), increased 18.1 ± 8.7% from baseline during the Epro/UFA condition, compared to a change of -5.7 ± 6.2% during the CHO condition (p < 0.001). The disposition index, a measure of pancreatic beta-cell function, increased during the Epro/UFA condition compared to the CHO condition (net difference 40%, p = 0.042), and low-density lipoprotein (LDL) peak particle size increased during the Epro/UFA condition compared to the CHO condition (net difference 0.27 nm, p = 0.019).  TG and very low-density lipoprotein cholesterol (VLDL-C) levels were lowered more following the Epro/UFA (~16% differences, p < 0.002) versus the CHO diet condition.  LDL-C was lowered by 9-10% with both diets, compared with baseline, but the response did not differ between diets.

Comment:

Consumption of a low-saturated fat diet, where ~16% of energy from refined starches and added sugars was replaced with Epro and UFA, increased indices of insulin sensitivity and pancreatic beta-cell function, increased LDL peak particle size, and lowered fasting TG and VLDL-C levels in men and women with elevated TG.  The results of this study are consistent with a previous study by our group, where daily consumption of three servings of sugar-sweetened products reduced insulin sensitivity by 18% as assessed by HOMA2-%S compared to a habitual diet baseline, and three daily servings of dairy products produced no change.  Reductions in TG and VLDL-C may benefit cardiometabolic health, and are often accompanied by a shift toward larger, more buoyant LDL particles.  This shift, as observed in the current trial, may result in a less atherogenic LDL particle.  The findings from this trial support the Dietary Guidelines for Americans’ recommendations to limit intake of refined starches and added sugars, and to emphasize UFA intake as replacements for both dietary saturated fatty acids and refined CHO.

References:

Maki KC, Palacios OM, Lindner E, Nieman KM, Bell M, Sorce J. Replacement of refined starches and added sugars with egg protein and unsaturated fats increases insulin sensitivity and lowers triglycerides in overweight or obese adults with elevated triglycerides. J Nutr. 2017;May 17 [Epub ahead of print]

Maki KC, Nieman KM, Schild AL, Kaden VN, Lawless AL, Kelley KM, Rains TM. Sugar-sweetened product consumption alters glucose homeostasis compared with dairy product consumption in men and women at risk of type 2 diabetes mellitus. J Nutr. 2015; 145:459-466. Available at http://jn.nutrition.org/content/145/3/459.full.pdf+html.

U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2015-2020 Dietary Guidelines for Americans 2015-2020. Eighth Edition. December 2015. Available at http://health.gov/dietaryguidelines/2015/guidelines/.

 

Replacing Refined Carbohydrates with Egg Protein