Potential Role of Nut Consumption for Improving Insulin Sensitivity : Results from a Systematic Review and Meta-analysis of Randomized Controlled Trials

Potential Role of Nut Consumption for Improving Insulin Sensitivity : Results from a Systematic Review and Meta-analysis of Randomized Controlled Trials

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

 

Worldwide incidence and prevalence of type 2 diabetes mellitus (T2D) diabetes are increasing at alarming rates, largely following increases in incidence of overweight and obesity.  The World Health Organization reports that ~1.9 billion adults are overweight in 2019, including 600 million that are obese and thus at heightened risk for T2D1.  Overweight and obesity are associated with impaired whole-body insulin sensitivity (i.e., increased insulin resistance), which is believed to be the key pathophysiologic link to increased risk for T2D 2.

 

Many epidemiological studies have examined the association of nut consumption with risks for T2D and mortality.  Systematic reviews and meta-analyses of prospective cohort studies have suggested a reduction in T2D risk with regular nut consumption 3-5

 

Tindall and colleagues recently published a review of 40 randomized, controlled trials with a median duration of 3 months (N = 2,832 subjects), that examined the effects of consuming tree nuts and peanuts on glycemic markers, including homeostasis model assessment of insulin resistance (HOMA-IR), fasting insulin and glucose, and glycated hemoglobin (HbA1C) 6.  The median intake of nuts was 52 g/d (range: 20-113 g/d).

 

In pooled analyses, consumption of tree nuts or peanuts reduced both HOMA-IR (weighted mean difference [WMD] −0.23; 95% confidence interval [CI] −0.40, −0.06; I2 = 51.7%) and fasting insulin (WMD −0.40 μU/mL; 95% CI −0.73, −0.07 μU/mL; I2 = 49.4%) compared to the control conditions 6.  However, there were no effects of nut consumption on fasting blood glucose (WMD −0.52 mg/dL; 95% CI −1.43, 0.38 mg/dL; I2 = 53.4%) or HbA1C (WMD 0.02%; 95% CI −0.01%, 0.04%; I2 = 51.0%).
 Further analyses showed no associations between the dose of nuts/peanuts consumed and the mean difference between nut and control treatments for any of the measured outcomes.  Analysis by nut type showed no deviations from the main results.

 

Comment. While there were no effects of nut consumption on HbA1C or fasting glucose, there were statistically significant reductions in HOMA-IR and fasting insulin, suggesting improved insulin sensitivity.  Future studies are needed to help determine the mechanisms through which nut/peanut consumption affects insulin sensitivity. 

 

References

  1. World Health Organization. Global report on diabetes. Geneva, Switzerland: World Health Organization; 2016. 

  2. Kahn SE, Hull RL, Utzschneider KM. Mechanisms linking obesity to insulin resistance and type 2 diabetes. Nature. 2006;444:840–6.
  3. Afshin A, Micha R, Khatibzadeh S, Mozaffarian D. Consumption of nuts and legumes and risk of incident ischemic heart disease, stroke, and diabetes: a systematic review and meta-analysis. Am J Clin Nutr 2014;100(1):278–88. 

  4. Aune D, Keum N, Giovannucci E, et al. Nut consumption and risk of cardiovascular disease, total cancer, all-cause and cause-specific mortality: a systematic review and dose-response meta-analysis of prospective studies. BMC Medicine 2016;14(1):207.
  5. Luo C, Zhang Y, Ding Y, et al. Nut consumption and risk of type 2 diabetes, cardiovascular disease, and all-cause mortality: a systematic review and meta-analysis. Am J Clin Nutr 2014;100(1):256–69. 

  6. Tindall AM, Johnston EA, Kris-Etherton PM, Petersen KS. The effect of nuts on markers of glycemic control: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2019;109:297–314.


 

Photo by Vitchakorn Koonyosying

No Additional Benefits on Cardiometabolic Risk Parameters of Reduced Red Meat or Increased Fiber Intake in an Energy-restricted Diet

No Additional Benefits on Cardiometabolic Risk Parameters of Reduced Red Meat or Increased Fiber Intake in an Energy-restricted Diet

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

 

To date, results from epidemiological studies have suggested that a high intake of red meat is associated with a higher risk of developing type 2 diabetes (T2D) while high fiber intake is associated with a lower risk 1-5. Furthermore, high intakes of red meat have also been suggested to be linked to increased risks of cardiovascular disease (CVD) and mortality 6,7.  One of the main approaches for reducing risk of T2D and CVD is weight loss 8-10. Research findings have also suggested that cardiometabolic risk can be improved with dietary modification independent of weight loss 11,12.

 

Willman et al. completed a 6-month, randomized controlled dietary intervention trial to assess whether lower intake of meat or higher intake of dietary fiber would have additional benefits when incorporated into an energy-restricted diet 13.  Subjects were randomized to one of three groups with all groups being instructed to reduce their caloric intakes by 400 kcal/d below their weight-maintenance requirements and exercise 3 hours/week.  The control group just decreased their caloric intake.  The “no red meat” group avoided red meat, but was able to eat turkey, fish or chicken, and subjects in the “fiber” group increased their fiber intake to at least 40 g/day.  The researchers also analyzed 9-month follow-up data from the Tuebingen Lifestyle Intervention Program (TULIP) cohort, which included subjects (n = 229) at increased risk of diabetes 14.  The intervention in TULIP consisted of increased physical activity and decreased caloric intake.

 

All participants in the 6-month trial lost weight (mean 3.3 ± 0.5 kg, P < 0.0001). Glucose tolerance and insulin sensitivity improved (P < 0.001), and body and visceral fat mass decreased in all groups (P < 0.001), with no difference among the groups.  Similarly, liver fat content decreased (P < 0.001) with no differences among the groups.  The liver fat decrease correlated with the decrease in ferritin during intervention (r2 = 0.08, P = 0.0021). This association between ferritin and liver fat changes was confirmed in TULIP (P = 0.0084).

 

Comment.  Neither the absence of dietary red meat nor the increase in fiber intake had an additional effect beyond calorie restriction and exercise on risk markers for T2D or CVD.  These results confirm that weight loss can lead to improvement in glucose metabolism, body fat composition and liver fat content and do not indicate incremental benefits for restriction of red meat intake or increasing dietary fiber intake.  Additional research is needed to assess effects of these dietary factors during weight loss maintenance.

 

References

  1. The InterAct Consortium. Association between dietary meat consumption and incident type 2 diabetes: The EPIC-InterAct study. Diabetologia 2013;56:47–59.
  2. Fretts AM, Howard BV, McKnight B, et al. Associations of processed meat and unprocessed red meat intake with incident diabetes: The Strong Heart Family Study. Am J Clin Nutr 2012;95:752–8.
  3. Lajous M, Tondeur L, Fagherazzi G, et al. Processed and unprocessed red meat consumption and incident type 2 diabetes among French women. Diabetes Care 2012;35:128–30.
  4. Pan A, Sun Q, Bernstein AM, et al. Red meat consumption and risk of type 2 diabetes: 3 cohorts of US adults and an updated meta-analysis. Am J Clin Nutr 2011;94:1088–96.
  5. Wittenbecher C, Mühlenbruch K, Kröger J, et al. Amino acids, lipid metabolites, and ferritin as potential mediators linking red meat consumption to type 2 diabetes. Am J Clin Nutr 2015;101:1241–50.
  6. Etemadi A, Sinha R, Ward MH, et al. Mortality from different causes associated with meat, heme iron, nitrates, and nitrites in the NIH-AARP Diet and Health Study: Population based cohort study. BMJ 2017;357:1957.
  7. Sun Q. Red meat consumption and mortality: Results from 2 prospective cohort studies. Arch Intern Med 2012;172:555.
  8. Tuomilehto J, Lindström J, Eriksson JG, et al. Prevention of type 2 diabetes mellitus by changes in lifestyle among subjects with impaired glucose tolerance. N Engl J Med 2001;344:1343–50. 

  9. Knowler WC, Barrett-Connor E, Fowler SE, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med 2002;346:393– 403. 

  10. Jensen MD, Ryan DH, Apovian CM, et al. 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and The Obesity Society. J Am Coll Cardiol 2014;63:2985– 3023. 

  11. Estruch R, Ros E, Salas-Salvadó J, et al. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med 2013;368:1279–90.
  12. Estruch R, Martínez-González MA, Corella D, et al. Effect of a high-fat Mediterranean diet on bodyweight and waist circumference: A prespecified secondary outcomes analysis of the PREDIMED randomised controlled trial. Lancet Diabetes Endocrinol 2016;4:666–76.
  13. Willmann C, Heni M, Linder K, et al. Potential effects of reduced red meat compared with increased fiber intake on glucose metabolism and liver fat content: a randomized and controlled dietary intervention study. Am J Clin Nutr. 2019;109:288–96.
  14. Schmid V, Wagner R, Sailer C, et al. Non-alcoholic fatty liver disease and impaired proinsulin conversion as newly identified predictors of the long-term non-response to a lifestyle intervention for diabetes prevention: Results from the TULIP study. Diabetologia 2017;60:2341– 51. 


 

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New Trial Suggests Light Therapy may be a Promising Intervention for Treatment of Depression with Type 2 Diabetes

New Trial Suggests Light Therapy may be a Promising Intervention for Treatment of Depression with Type 2 Diabetes

By Aly Becraft, MS; Kevin C Maki, PhD

One in 11 adults have diabetes worldwide,1 with an estimated 25% of people with diabetes also suffering from depression.2 Co-occurrence of these diseases has been shown to increase risk for diabetes complications,3 potentially due to a lack of motivation to properly manage the disease.4,5 Therefore, people with diabetes and depression need effective therapies for both conditions in order to remain properly treated.

Often, depression simultaneously occurs with impaired sleep, leading to biological rhythm disturbances.6 While pharmacological interventions can be successful, some antidepressant drugs may have unfavorable effects on glycemic control in people with type 2 diabetes (T2D).7 Light therapy is an alternative or adjunctive treatment for depression with minimal side effects.8 It is thought to act by modifying the phase relationships between the biological clock and the light-dark cycle to restore appropriate sleep-wake cycles9 and has proven effective for treating seasonal depression (seasonal affective disorder) as well as some cases of non-seasonal depression.10-12 In 2017, an estimated 12% of global health expenditures were spent on diabetes,1 thus, if efficacy can demonstrated, light therapy would be a cost-effective treatment for T2D patients suffering from depression. In addition to altering mood states, sleep deficiency may also be related to changes in glucose metabolism and decreased insulin sensitivity.13 Previous studies have reported that partial sleep deprivation induced insulin resistance in healthy subjects and patients with type 1 diabetes.13-15 Therefore, the restoration of biological rhythmicity in individuals with impaired sleep may have the potential to improve glucose regulation.

Brouwer et al., (2019) report results from a randomized, double-blind, placebo-controlled trial which was published in Diabetes Care and investigated whether mood and insulin sensitivity could be improved via light therapy in clinically depressed patients with T2D.16 In this parallel-arm study, a total of 79 adults with depression and T2D were included in the outcome measures. Forty received light therapy (broad-spectrum, white-yellow light, 10,000 lux), while 39 received placebo therapy (monochromatic green light, 470 lux). Light therapy was provided in the homes of participants over 4 weeks for 30 minutes each morning. Participants were assessed for changes in depressive symptoms, and a subset of participants who agreed to hyperinsulinemic-euglycemic clamp (HEC) procedure were evaluated for insulin sensitivity. Both measures were assessed at baseline and after the 4-week intervention. Several secondary measures were also evaluated including anxiety symptoms, diabetes stress, self-reported insomnia, objective sleep duration, sleep efficiency, and mid-sleep time, as well as glycated hemoglobin (HbA1C) levels, fasting blood glucose, self-reported hypo-glycemic events and body weight.

After the intervention, light therapy did not significantly reduce depressive symptoms, and similarly, had no effect on insulin sensitivity in the primary analysis. However, per-protocol analyses were conducted to exclude 13 participants that changed glucose-lowering medication during the protocol, which resulted in 51 remaining participants.  In the per-protocol analysis, participants had a 26% greater reduction in depressive symptoms in response to light therapy (P=0.031). In addition, subgroup analysis suggested that patients with higher insulin resistance responded positively to light therapy (P=0.017), and there was a trend toward positive response in patients using insulin vs non-insulin glucose lowering medication (P=0.094). No significant differences in secondary measures were found between the treatment and placebo groups.

Comment.  Overall, the results of this study were inconclusive, but the per-protocol analysis was suggestive of improvements in depressive symptoms, which is a hypothesis-generating finding that should be investigated in additional research. Furthermore, the reduction in depressive symptoms observed in patients with higher insulin resistance may indicate greater efficacy of light therapy in this subset. A similar observation by Dimitrova et al., (2017) suggested that higher BMI, a factor strongly associated with insulin resistance, may be a baseline predictor for light therapy response in patients with seasonal depression.17 Although improvements in insulin sensitivity have been previously demonstrated in two case studies in response to light therapy,18,19 this effect was not established in the present study. This study shows potential for light therapy as a treatment for depression with T2D, but more research is needed with larger samples, longer duration of therapy and/or greater daily light exposure to more fully evaluate the effects of this therapy.

 

References:

  1. Cho NH, Shaw JE, Karuranga S, et al. International Diabetes Federation (IDF) diabetes atlas: global estimates of diabetes prevalence for 2017 and projections for 2045. DiabetesRes Clin Pract. 2018;138:271-281.
  2. Goldney RD, Phillips PJ, Fisher LJ, Wilson DH. Diabetes, depression, and quality of life: a population study. Diabetes Care. 2004;27(5):1066-1070.
  3. Petrak F, Baumeister H, Skinner TC, et al. Depression and diabetes: treatment and health-care delivery. Lancet Diabetes Endocrinol. 2015;3:472-485.
  4. Gonzalez JS, Peyrot M, McCarl LA, et al. Depression and diabetes treatment nonadherence: a meta-analysis. Diabetes Care. 2008;31:2398-2403.
  5. Lin EH, Katon W, Von Korff M, et al. Relationship of depression and diabetes self-care, medication adherence, and preventive care. Diabetes Care. 2004;27:2154-2160.
  6. van Mill JG, Hoogendijk WJ, Vogelzangs N, et al. Insomnia and sleep duration in a large cohort of patients with major depressive disorder and anxiety disorders. J Clin Psychiatry. 2010;71:239-246.
  7. Deuschle M. Effects of antidepressants on glucose metabolism and diabetes mellitus type 2 in adults. Curr Opin Psychiatry. 2013;26:60-65.
  8. Wirz-Justice A, Benedetti F, Terman M. Chronotherapeutics for affective disorders: a clinician's manual for light and wake therapy, 2nd. Karger Medical and Scientific Publishers. 2013.
  9. Wirz-Justice A. Biological rhythm disturbances in mood disorders. Int Clin 2006;21:S11-5.
  10. Tuunainen A, Kripke DF, Endo T. Light therapy for non-seasonal depression. Cochrane Database Syst Rev. 2004;(2):CD004050.
  11. Perera S, Eisen R, Bhatt M, et al. Light therapy for non-seasonal depression: systematic review and meta-analysis. BJPsych Open. 2016;2:116-126.
  12. Mårtensson B, Pettersson A, Berglund L, Ekselius L. Bright white light therapy in depression: a critical review of the evidence. J Affect Disord. 2015;182:1-7.
  13. Spiegel K, Tasali E, Leproult R, Van Cauter E. Effects of poor and short sleep on glucose metabolism and obesity risk. Nat Rev Endocrinol. 2009;5(5):253.
  14. Donga E, van Dijk M, van Dijk JG, et al. A single night of partial sleep deprivation induces insulin resistance in multiple metabolic pathways in healthy subjects. J Clin Endocrinol Metab. 2010;95(6):2963-2968.
  15. Donga E, van Dijk M, van Dijk JG, et al. Partial sleep restriction decreases insulin sensitivity in type 1 diabetes. Diabetes Care. 2010;33:1573-1577.
  16. Brouwer A, Nguyen HT, Rutters F, et al. Effects of light therapy on mood and insulin sensitivity in patients with type 2 diabetes and depression: results from a randomized placebo-controlled trial. Diabetes Care. 2019.
  17. Dimitrova TD, Reeves GM, Snitker S, et al. Prediction of outcome of bright light treatment in patients with seasonal affective disorder: discarding the early response, confirming a higher atypical balance, and uncovering a higher body mass index at baseline as predictors of endpoint outcome. J Affect Disord. 2017;222: 126-132.
  18. Nieuwenhuis RF, Spooren PF, Tilanus JJ. Less need for insulin, a surprising effect of phototherapy in insulin-dependent diabetes mellitus. Tijdschr Psychiatr. 2009;51:693-697.
  19. Allen NH, Kerr D, Smythe PJ, et al. Insulin sensitivity after phototherapy for seasonal affective disorder. Lancet. 1992;339:1065-1066.

 

 

Photo by Duy Hoang

Viscous Fiber Supplements in Diabetes Control: Results from a Systematic Review and Meta-analysis of Randomized Controlled Trials

Viscous Fiber Supplements in Diabetes Control: Results from a Systematic Review and Meta-analysis of Randomized Controlled Trials

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

According to the recent 2019 American Diabetes Association (ADA) Standards of Medical Care in Diabetes, people with diabetes should increase their intake of viscous fiber from sources such as oats, legumes, and citrus to help regulate blood glucose levels and lower risk of cardiovascular disease1. Viscous fibers are described as such because they increase viscosity in the human gut, thereby reducing the rate at which carbohydrates are digested and the glucose molecules from them absorbed.  These effects occur because the viscous solution impedes the ability of digestive enzymes to reach starch molecules and slows the rate at which glucose molecules reach the brush border in the intestinal lumen, where absorption can occur.  The result is flattening of the postprandial glycemic and insulinemic responses.  While these acute effects are well established, the longer-term impacts of viscous fibers on glycemic control markers are not well known2.

 

In a systematic review and meta-analysis, Jovanovski2 investigated the effect of viscous dietary fiber supplementation on markers of glycemic control in people with type 2 diabetes (T2D).  A comprehensive literature search on MEDLINE, Embase, and Cochrane Central Register of Controlled Trials through June 15, 2018 identified 2,716 potential RCTs.  After reviewing the studies based on the inclusion/exclusion criteria, 27 studies (n = 1,394) were identified for the review and meta-analysis.  Inclusion criteria were: ≥3 weeks in duration, studied viscous fiber supplementation (β-glucan, guar gum, konjac, psyllium, pectin, xanthan gum, locust bean gum, alginate, agar) compared to an appropriate control (i.e., fiber-free supplement or one containing insoluble fiber, background diet, or placebo), and included at least one glycemic measurement (glycated hemoglobin [HbA1c], fasting glucose, fasting insulin, homeostatic model assessment of insulin resistance [HOMA-IR], or fructosamine).

 

The median age of subjects was 60 years (range 48-67) and they had a median body mass index of 27 kg/m2 (range 26-32 kg/m2).  The median dose of viscous fibers in the studies was 13.1 g/day (range 2.55-21.0 g/day) and the median study duration was 8 weeks (range 3-52 weeks).

 

Compared to control groups, inclusion of viscous fiber in the diet was associated with significant reductions in HbA1c, fasting blood glucose and HOMA- IR. 

 

  • HbA1c: mean difference (MD) -0.58% 95% confidence interval (CI) -0.88%, -0.28%; p = 0.0002;
  • Fasting blood glucose: MD -14.8 mg/dL 95% CI -23.8, -5.59; p = 0.001
  • HOMA-IR: MD -1.89 95% CI -3.45, -0.33; p = 0.02.

 

There were no differences between viscous fiber groups and controls for fasting insulin (MD -2.53 µU/mL 95% CI -5.41, 0.35; p = 0.08) or fructosamine (MD -0.12 mmol/L 95% CI -0.39, 0.14; p = 0.37).  Only 2 studies reported fructosamine, so this finding should be interpreted with caution.  There was no evidence of a significant dose-response effect.  Results for HbA1c, fasting glucose, fasting insulin, and HOMA-IR were graded moderate for certainty of evidence, while fructosamine was graded low.

 

Comment.  Viscous fiber intake, through consumption of food sources such as legumes, whole fruits (e.g., apples and pears) and whole grain oats and barley, as well as dietary supplementation with products such as psyllium (e.g., Metamucil®), methylcellulose (e.g., Citrucel®) or konjac (e.g., Lipozene®), appears to have several benefits regarding cardiometabolic health.  For those with T2D, this meta-analysis shows evidence to support favorable effects on glycemic control and insulin sensitivity.  More research is needed to establish more clearly whether all viscous fibers enhance insulin sensitivity, or whether this property is limited to those with certain characteristics, such colonic fermentability or content of specific bioactive compounds3,4.  Evidence from other sources also shows that viscous fiber lowers the circulating cholesterol level, likely by trapping cholesterol and bile acids, thus preventing their absorption/reabsorption3.  In addition, viscous fibers appear to play a role in appetite regulation, enhancing satiety after meal5.

 

The meta-analysis by Jovanovski and colleagues shows that inclusion of viscous fiber in the diet produces clinically meaningful improvements in glycemic control for patients with T2D.  Based on this, as well as evidence for other benefits (cholesterol lowering and enhanced satiety), inclusion of viscous fiber from foods and/or supplements should be considered an important component of the management plan for patients with T2D.

 

References

  1. American Diabetes Association. 10. Cardiovascular Disease and Risk Management: Standards of Medical Care in Diabetes—2019. Diabetes Care. 2019;42(Supplement 1): S103-S123.

 

  1. Jovanovski E, Khayyat R,  Zurbau A,  et al. Should viscous fiber supplements be considered in diabetes control? Results from a systematic review and meta-analysis of randomized controlled trials. Diabetes Care. 2019 Jan; doi:10.2337 [Epub ahead of print].

 

  1. Weickert MO, Pfeiffer AFH. Impact of dietary fiber consumption on insulin resistance and the prevention of type 2 diabetes. J Nutr. 2018;148:7-12.

 

  1. Kärkkäninen O, Lankinen MA, Vitale M, et al. Diets rich in whole grains increase betainized compounds associated with glucose metabolism. Am J Clin Nutr. 2018;108:971-979.

 

  1. Rebello CJ, Chu YF, Johnson WD, et al. The role of meal viscosity and oat ß–glucan characteristics in human appetite control: a randomized crossover trial. Nutr J. 2014;13:49.

 

 

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Substituting a Type-4 Resistant Starch for Available Carbohydrate Reduces Postprandial Glucose, Insulin and Hunger: An Acute, Randomized, Double-Blind, Controlled Study

Substituting a Type-4 Resistant Starch for Available Carbohydrate Reduces Postprandial Glucose, Insulin and Hunger:  An Acute, Randomized, Double-Blind, Controlled Study1

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

 Background:

Dietary fiber (including a wide variety of nondigestible carbohydrates) is a noted shortfall nutrient in Western diets, despite the fact that appropriate consumption is associated with a broad range of health benefits.2,3 One of the benefits that has received considerable attention is blunting of postprandial blood glucose control. Researchers have established a benefit between consumption of viscous fibers and blood glucose excursions.4 When certain fibers, such as resistant starch (RS), are used in place of available carbohydrate in foods, less glucose is liberated through digestion, thus lowering the rate and quantity of glucose entering the bloodstream after a meal.5

It is important to note that there are different types of RS receiving varying levels of attention in clinical trials. These differences are outlined in the table below.

Type of RS

Description

Amount of Research

Resistant starch type-2

Granular, native starch

Resistant to digestion

Majority of clinical research is in these 2 areas

Resistant starch type-3

Retrograded starch

Resistant to digestion

Resistant starch type-4 (RS4)

Chemically modified starch

Resists digestion by intestinal enzymes

Fewer clinical trials in this area

Among the types of RS4, phosphate distarch phosphate is the most frequently tested6-8, with fewer studies on hydroxypropyl distarch phosphate9,10 and only one study on acid hydrolyzed and heat treated RS4, to date.11

The primary aim of this study was to characterize the postprandial blood glucose response in healthy adults to a novel RS4 (acid hydrolyzed and heat treated maize-based RS) in a ready-to-eat baked good (scone), compared with the response to consumption of a scone made with a control starch. The secondary aims were to evaluate postprandial insulin response, satiety and gastrointestinal tolerance. It was hypothesized that the replacement of digestible carbohydrate from refined wheat flour with RS4 would reduce postprandial blood glucose.

 Methods:

This was a double-blind, randomized, controlled trial conducted at MB Clinical Research in Boca Raton, Florida, USA.

Main Entry Criteria:

  • Age 18-74 y
  • Men and women
  • Body mass index (BMI) 18.5-29.99 kg/m2
  • General good health
  • Fasting capillary glucose <100 mg/dL

The treatment fiber scone contained VERSAFIBE™ 2470 resistant starch (provided by Ingredion Incorporated, Bridgewater, NJ) as the primary fiber source. VERSAFIBE™ 2470 is a RS4 with 70% dietary fiber and is produced from food grade high-amylose maize starch. Acid hydrolysis and heat treatment both reduce the digestibility of this high-amylose maize starch resulting in increased RS4 and total dietary fiber in the finished product. There are no nonstarch polysaccharides present in VERSAFIBE™ 2470. The nutrition composition of the Fiber Scone and Control Scone are shown in the following table.

 

Per Serving, As-Eaten

Control Scone

Fiber

Scone

Weight (g)

83.9

84.1

Calories (kcal)

328

270

Fat (g)

16.0

14.4

Saturated fat (g)

5.0

4.7

Protein (g)

7.1

6.1

Total Carbohydrates (g)

42.8

46.4

Available Carbohydrates (g)

38.8

28.9

Dietary Fiber (g)*

4.0

17.5

Sugars (g)

14.8

14.9

*VERSAFIBE™ 2470 resistant starch provided 16.5 g dietary fiber in the Fiber Scone

The subjects attended 3 study visits, one for screening and two test visits. At the test visits, subjects consumed the Control Scone or Fiber Scone (randomly assigned sequence) with 240 mL water.  Capillary glucose, plasma glucose and plasma insulin were measured pre-consumption and at t = -15, 15, 30, 45, 60, 90, 120 and 180 min ± 2 min, where t = 0 was the start of the study product consumption. Satiety visual analog scale (VAS) ratings were assessed pre-consumption and at 3 min intervals.  Questionnaires were used to assess Gastrointestinal (GI) Tolerability and product palatability at each test visit.

 Results:

A total of 36 subjects were randomized in the study, and one was withdrawn due to non-compliance. Ultimately, 32 subjects were included in the glucose and insulin analyses and 35 were included in the satiety VAS, GI tolerability and palatability analyses.

Consumption of the Fiber Scone significantly reduced postprandial glucose and insulin incremental areas under the curve (43-45% reduction and 35-40% reduction, respectively, p<0.05 for both) as well as postprandial glucose and insulin maximum concentrations (8-10% and 22% reductions, respectively, p<0.05 for both).  Ratings of hunger and desire to eat were also significantly reduced following consumption of the Fiber Scone vs. the Control Scone during the 180 minutes after intake (p<0.05) and there were no GI side effects with the Fiber Scone compared with Control.

Comment:

This study shows significant reductions in postprandial glucose and insulin levels associated with the replacement of refined carbohydrate with RS4 in healthy subjects. In addition, ratings of hunger and desire to eat were reduced after consumption of the RS4-containing food product, a first for this specific RS ingredient. Incorporation of a fiber such as RS4 into the diet has potential clinical and practical relevance due to favorable impacts on markers of cardiometabolic health.12,13

References:

  1. Stewart ML, Wilcox ML, Bell M, Buggia MA, Maki KC. Type-4 resistant starch in substitution for available carbohydrate reduces postprandial glycemic response and hunger in acute, randomized, double-blind, controlled study. Nutrients. 2018;10(2).
  2. Dahl WJ, Stewart ML. Position of the Academy of Nutrition and Dietetics: Health implications of dietary fiber. J Acad Nutr Diet. 2015;115:1861-1870.
  3. Stephen AM, Champ MM, Cloran SJ, et al. Dietary fibre in Europe: current state of knowledge on definitions, sources, recommendations, intakes and relationships to health. Nutr Res Rev. 2017;30:149-190.
  4. Tosh SM. Review of human studies investigating the post-prandial blood-glucose lowering ability of oat and barley food products. European J Clin Nutr. 2013;67:310-317.
  5. Robertson MD. Dietary-resistant starch and glucose metabolism. Curr Opin Clin Nutr Metab Care. 2012;15:362-367.
  6. Haub MD, Hubach KL, Al-Tamimi EK, Ornelas S, Seib PA. Different types of resistant starch elicit different glucose reponses in humans. J Nutr Metab. 2010;2010.
  7. Al-Tamimi EK, Seib PA, Snyder BS, Haub MD. Consumption of cross-linked resistant starch (RS4(XL)) on glucose and insulin responses in humans. J Nutr Metab. 2010;2010.
  8. Martinez I, Kim J, Duffy PR, Schlegel VL, Walter J. Resistant starches types 2 and 4 have differential effects on the composition of the fecal microbiota in human subjects. PLoS One. 2010;5:e15046.
  9. Shimotoyodome A, Suzuki J, Kameo Y, Hase T. Dietary supplementation with hydroxypropyl-distarch phosphate from waxy maize starch increases resting energy expenditure by lowering the postprandial glucose-dependent insulinotropic polypeptide response in human subjects. Br J Nutr. 2011;106:96-104.
  10. Gentile CL, Ward E, Holst JJ, et al. Resistant starch and protein intake enhances fat oxidation and feelings of fullness in lean and overweight/obese women. Nutr J. 2015;14:113.
  11. Stewart ML, Zimmer JP. Post-prandial glucose and insulin response to high-fiber muffin top containing resistant starch type 4 in healthy adults: a double-blind, randomized, controlled trial. Nutrition. 2018 (in press).
  12. Maki KC, Pelkman CL, Finocchiaro ET, et al. Resistant starch from high-amylose maize increases insulin sensitivity in overweight and obese men. J Nutr. 2012;142:717-723.
  13. Marlatt KL, White UA, Beyl RA, et al. Role of resistant starch on diabetes risk factors in people with prediabetes: design, conduct, and baseline reuslts of the STARCH trial. Contemp Clin Trials. 2018;65:99-108.
tape measure

Breakfast Skippers Beware: Newly Published Data on Breakfast Patterns Identifies Association with Atherosclerosis, Independent of Cardiovascular Disease Risk Factors

Breakfast Skippers Beware: Newly Published Data on Breakfast Patterns Identifies Association with Atherosclerosis, Independent of Cardiovascular Disease Risk Factors

Insights from the Progression of Early Subclinical Atherosclerosis (PESA) Study

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

 Background: It is well accepted that a person’s lifestyle may impact markers of overall health. Factors associated with lifestyle may be dependent on cultural, social and psychological practices as they fit into a daily routine. Researchers have paid particular attention to the lifestyle habit of breakfast consumption (or non-consumption) and how it may contribute to disease risk.

Whether or not a person consumes breakfast has correlations to such factors as:

  • Measures of satiety,
  • Daily energy intake,
  • Metabolic efficiency of the diet,
  • Appetite regulation.

The regular omission of breakfast has associations with increased cardiovascular health markers such as obesity, diabetes, and unfavorable lipid profiles. Although there have been studies investigating the impacts of breakfast skipping behaviors with heart disease risk, the current study may be the first to research an association between breakfast patterns and subclinical atherosclerosis. The aim of the Progression of Early Subclinical Atherosclerosis (PESA) study1 was to characterize the association between different breakfast patterns and cardiovascular disease (CVD) risk factors; especially focusing on whether the regular omission of breakfast is associated with subclinical atherosclerosis (noted by investigating the presence of atherosclerotic plaques in the carotid arteries, aorta, and iliofemoral arteries or coronary artery calcium in a population with no previous CVD history).

 Methods: The PESA study is an ongoing observational prospective cohort of 4,082 employees of the Bank Santander Headquarters in Madrid, Spain. Male and female volunteers, aged 40 to 54 years old, were included if they met the following criteria:

  • Free of any CVD or chronic kidney disease,
  • No previous transplant,
  • Did not exceed body mass index (BMI) of 40 kg/m2,
  • Did not have any disease that might affect life expectancy and decrease it to <6 years.

Estimates of usual diet were determined through the use of a computerized questionnaire, which was developed and validated in the Estudio de Nutrición y Riesgo Cardiovascular (ENRICA) study of a Spanish population and contains nutritional information on 861 food items including many typically consumed Spanish meals and dishes. Subjects reported the foods consumed in the past 15 days while also noting specific occasions throughout the day (waking up, breakfast, mid-morning, lunch, mid-afternoon, and dinner). To characterize breakfast patterns, the researchers first utilized the quantitative description of breakfast provided by Timlin and Pereira2: “the first meal of the day that breaks the fast after the longest period of sleep, eaten before the start of daily activities (e.g., errands, travel, work), within 2 h of waking, typically no later than 10:00 in the morning, and an energy level between 20 and 35% of total daily energy need.” Additional input was gathered by application of a qualitative definition of breakfast by O’Neill et al. where breakfast is defined as “a food or beverage from at least one food group, and may be consumed at any location. Coffee, water and nonalcoholic beverages are not included in a food group.”3 Mean energy intake of the subjects in the PESA study was 2,314 kcal/day; three major breakfast groups were identified:

  • <5% total energy intake (EI) = skipping breakfast (SBF)
  • 5 to 20% total EI from breakfast = low-energy breakfast (LBF)
  • >20% total EI from breakfast = high-energy breakfast (HBF)

Anthropometric data were collected and CVD risk factors and metabolic syndrome (MetS) were assessed. The European Society of Cardiology CVD risk assessment tool, the Systematic Coronary Risk Evaluation, was used to assess fatal cardiovascular risk. Additionally, researchers noted variables such as age, gender, marital status, highest educational level, smoking status, diet practices and physical activity. Specific ultrasound equipment was utilized to assess atherosclerotic plaque in multiple vascular areas: bilateral carotid, infrarenal abdominal aorta and iliofemoral arteries. Plaques were defined as “focal protrusion into the arterial lumen of thickness >0.5 mm or >50% of the surrounding intima-media thickness or a diffuse thickness >1.5 mm measured between the media-adventitia and intima-lumen interfaces.” Coronary artery calcium (CAC) was also assessed, and states of atherosclerosis were defined as follows:

 

State of Atherosclerosis Definition
Subclinical atherosclerosis The presence of plaque in the right carotid, left carotid, aorta, right iliofemoral, or left iliofemoral or as the presence of calcium (CAC score > 0) in the coronary arteries
Non-coronary atherosclerosis The presence of plaque in the above areas and excluding CAC
Generalized atherosclerosis Dependent on the number of sites affected with atherosclerosis; 4 to 6 sites affected

 

Results: Of the 4,052 participants, 2.9%, 69.4% and 27.7% fell into the SBF (breakfast skipping), LBF (low-energy breakfast) and HBF (high-energy breakfast) categories, respectively. Compared with HBF and LBF, the SBF group was made up mostly of men, current smokers, subjects who had reportedly changed their diet in the previous year to lose weight, and subjects who consumed their highest energy intake at lunch. Compared with HBF, the LBF subjects were more likely to be men with lower education level and to be current smokers with higher calorie intakes at lunch.

Regarding diet quality, the subjects in the SBF group were most likely to have higher energy, protein (from animal sources) and dietary cholesterol intakes while also having the lowest fiber and carbohydrate intakes and greatest consumption of alcoholic and sugar-sweetened beverages and red meat.  The LBF group (compared with HBF) had higher overall energy, animal protein and cholesterol intakes and lower intakes of sugar and polysaccharides while also having dietary patterns lower in fruits, vegetables, whole grains and olive oil and higher in refined grains, red meat, fast food and precooked meals (as well as lean meat and seafood). The HBF group had the greatest intakes of dietary fiber, fruits and vegetables, whole grains and high-fat dairy.

The cardiometabolic risk marker profile was less favorable in the LBF and SBF groups, including higher levels of waist circumference, BMI, blood pressure, blood lipids and fasting blood glucose. Participants in the SBF group had a greater likelihood of scoring high on the European Society of Cardiology Systematic Coronary Risk Evaluation risk scale. Probabilities of obesity, abdominal obesity, MetS, low high-density lipoprotein cholesterol, and hypertension were significantly greater for the SBF group compared with HBF.  The prevalence values for atherosclerosis (subclinical, non-coronary and generalized) across all PESA subjects were 62.5%, 60.3% and 13.4%, respectively.

The odds ratios (ORs) for subclinical atherosclerosis were significantly elevated in the SBF group compared with the HBF group:

  • Abdominal aorta - OR 1.79, 95% confidence interval (CI) 1.16 to 2.77,
  • Carotid atherosclerotic plaques - OR 1.76, 95% CI 1.17 to 2.65,
  • Iliofemoral plaques - OR 1.72, 95% CI 1.11 to 2.64,
  • Coronary atherosclerosis – OR 1.55, 95% CI 0.97 to 2.46,
  • Non-coronary and generalized atherosclerosis - OR 2.57, 95% CI 1.54 to 4.31.

The participants in the LBF group had greater risk of carotid or iliofemoral atherosclerotic plaques compared with the HBF group (OR 1.21; 95% CI 1.03 to 1.43 and OR 1.17; 95% CI 1.00 to 1.37, respectively).

Comment: The results from the PESA study indicate that regular skipping of breakfast was associated with 1.55- to 2.57-fold higher odds for subclinical atherosclerosis, even after adjustment for traditional CVD risk factors and diet quality. Breakfast skipping behavior was also linked to an overall unhealthy lifestyle (poor overall diet, higher consumption of alcohol and smoking).  Other researchers have also noted these same associations in that skipping breakfast is often associated with smoking4, greater total energy intake5, and noncompliance with “Healthy Eating” recommendations.6

Results from PESA confirm the association between breakfast skipping and an adverse cardiometabolic risk marker profile and further show that breakfast skipping is independently associated with subclinical measures of atherosclerosis.  However, the degree to which this association might be causal vs. reflective of residual confounding due to greater exposure to CVD risk markers over time is uncertain.

Several studies have demonstrated that insulin sensitivity shows diurnal variation.  For example, Saad et al. reported that mean values for an index of insulin sensitivity produced from postprandial responses to identical meals at breakfast, lunch and dinner were 11.2, 7.9 and 8.1 (units = 10-4 dL/kg/min/mU/mL).7  Thus, insulin sensitivity was ~40% higher in the morning compared with the afternoon or evening.  It is possible that consuming a lower percentage of daily energy during the times of day when insulin sensitivity is highest (consumption of a low-energy breakfast or breakfast skipping) has an adverse impact on the cardiometabolic risk profile, increasing risks for both type 2 diabetes mellitus and atherosclerotic CVD, although prospective trials will be needed to investigate this possibility.8

 References

  1. Uzhova I, Fuster V, Fernandez-Ortiz A, et al. The Importance of Breakfast in Atherosclerosis Disease: Insights From the PESA Study. J Am Coll Cardiol. 2017;70(15):1833-1842.
  2. Timlin MT, Pereira MA. Breakfast frequency and quality in the etiology of adult obesity and chronic diseases. Nutr Rev. 2007;65(6 Pt 1):268-281.
  3. O'Neil CE, Byrd-Bredbenner C, Hayes D, Jana L, Klinger SE, Stephenson-Martin S. The role of breakfast in health: definition and criteria for a quality breakfast. J Acad Nutr Diet. 2014;114(12 Suppl):S8-S26.
  4. Nishiyama M, Muto T, Minakawa T, Shibata T. The combined unhealthy behaviors of breakfast skipping and smoking are associated with the prevalence of diabetes mellitus. Tohoku J Exp Med. 2009;218(4):259-264.
  5. van der Heijden AA, Hu FB, Rimm EB, van Dam RM. A prospective study of breakfast consumption and weight gain among U.S. men. Obesity (Silver Spring, Md). 2007;15(10):2463-2469.
  6. Smith TJ, Dotson LE, Young AJ, et al. Eating patterns and leisure-time exercise among active duty military personnel: comparison to the Healthy People objectives. J Acad Nutr Diet. 2013;113(7):907-919.
  7. Saad A, Dalla Man C, et al. Diurnal pattern to insulin secretion and insulin action in healthy individuals. Diabetes. 2012;61(11):2691-2700.
  8. Maki KC, Phillips-Eakley AK, Smith KN. The effects of breakfast consumption and composition on metabolic wellness with a focus on carbohydrate metabolism. Adv Nutr. 2016;7 (Suppl 6):613S-621S.

 

Photo by Brooke Lark

MB Clinical Academy Releases its First Two Educational Programs

MB Clinical Academy

MB Clinical Academy Releases its First Two Educational Programs

MB Clinical Academy produces educational materials to help clinicians, clinical research professionals and students more effectively manage the cardiometabolic health of their patients/clients, and to understand the strengths and limitations of the available evidence, including gaps that can be filled with future studies.

We have just completed two new programs, which will be available for purchase and download during the week of July 10, 2017.

Short Course

Diet and Prevention of Type 2 Diabetes Mellitus:  Beyond Weight Loss and Exercise

This short course will review the evidence for dietary factors in the prevention of type 2 diabetes mellitus (T2D).  It contains three modules that will cover:

  • Module 1: Epidemiology and pathophysiology of T2D
  • Module 2: Predictors of T2D risk and effects of interventions on incidence
  • Module 3: Summary of the associations and mechanisms through which diet may affect T2D risk, with an emphasis on insulin sensitivity and glycemic load

Short Course

Interpreting Efficacy Results from Cardiovascular Outcomes Trials

Cardiovascular outcomes trials are integral to evidence-based medicine, and they are the most effective means for demonstrating that an intervention reduces major adverse cardiovascular events.  A sound understanding of the fundamentals of clinical study design and statistical methodology is essential for the interpretation of efficacy results from cardiovascular outcomes trials.  However, most clinicians have not had extensive training on how to interpret measures of association and statistical procedures used to assess the efficacy of interventions intended to reduce cardiovascular event risk.  This course will review of the following concepts and their use in cardiovascular outcomes studies:

  • Measures of cardiovascular event incidence
    1. Relative risk
    2. Hazard ratio
    3. Odds ratio
  • Comparing event rates and treatment effects
    1. Relative risk reduction
    2. Absolute risk reduction
    3. Number needed to treat (or harm)
  • Pitfalls when making comparisons between cardiovascular outcomes trials, including the three most important questions
    1. Who was studied (risk profile)?
    2. What outcomes were assessed?
    3. Over what time period?
  • Additional factors to consider in the interpretation of findings from cardiovascular outcomes trials
    1. Evaluating the roles of chance, bias and confounding
    2. Factors affecting validity and generalizability
    3. Assessing the potential for type I and type II statistical errors

We expect that those who purchase these programs will find them informative and practical.  If you have suggestions for future programs, don’t hesitate to send us an email:  info@mbclinicalresearch.com.

 

MB Clinical Academy

Dr. Ralph Defronzo Interview

Dr. Ralph Defronzo Interview

Dr. Ralph Defronzo Interview

Dr. Ralph Defronzo Interview

Steve Freed, RPh, CDE from Diabetes in Control conducted a terrific interview with Ralph DeFronzo, MD, who is an endocrinologist and Deputy Director of the Texas Diabetes Institute.  Dr. DeFronzo has been a pioneer in conducting studies to elucidate the pathophysiology of type 2 diabetes mellitus, and in the evaluation of treatment strategies that address the underlying defects.  Dr. DeFronzo recently surpassed 750 publications and it is difficult to overstate his influence on the field of diabetology.  The full interview on video and a transcript may be obtained at www.diabetesincontrol.com and http://www.diabetesincontrol.com/dr-ralph-defronzo-full-transcript/.

Below is a summary of Dr. DeFronzo’s key points.

  1. Impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) are two subtypes of prediabetes with different pathophysiologies:
    • IFG is characterized by hepatic insulin resistance and impaired first-phase insulin secretion;
    • IGT is characterized by skeletal muscle insulin resistance and impairment of second-phase insulin secretion.
  2. Progressive loss of pancreatic beta-cell function is the hallmark of progression from prediabetes to type 2 diabetes mellitus (T2D), and then to more severe T2D. Impairment of beta-cell response is due to a combination of dysfunction (hibernation) and loss of beta-cell mass.  This process can be arrested or slowed by drug therapies that have direct or indirect effects.
    • Direct effects – thiazolidinediones and GLP-1 agonists appear to have direct effects on the pancreas that help to preserve beta-cell mass, in part through reducing apoptosis.
    • Indirect effects – other drugs that lower glucose will reduce glucose toxicity, which, in turn, will improve beta-cell function and insulin sensitivity. DeFronzo believes that sulfonylureas should rarely be used and favors metformin and SGLT-2 inhibitors over other classes of glucose-lowering drugs.
  3. Recently published data support effects of three classes of hypoglycemic agents to reduce cardiovascular risk.
    • Pioglitazone (a thiazolidinedione) – the IRIS trial
    • SGLT-2 inhibitors – EMPA-REG Outcome and CANVAS
    • GLP-1 agonists – SUSTAIN-6 and LEADER
  4. DeFronzo advocates triple-therapy from early in the disease process (which can be costly) to address the underlying insulin resistance and arrest the progression of beta-cell impairment. This involves use of:
    • Pioglitazone (a thiazolidinedione),
    • A GLP-1 agonist,
    • Metformin or an SGLT-2 inhibitor.

Abbreviations:  CANVAS, Canagliflozin Cardiovascular Assessment Study; EMPA-REG, Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients; GLP-1, glucagon-like peptide-1; IFG, impaired fasting glucose; IGT, impaired glucose tolerance; IRIS, Insulin Resistance Intervention after Stroke; LEADER, Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Outcome Results; SGLT-2, sodium-glucose cotransporter-2; SUSTAIN-6, Trial to Evaluate Cardiovascular and Other Long-term Outcomes with Semaglutide in Subjects with Type 2 Diabetes; T2D, type 2 diabetes mellitus.

Relevant references

Abdul-Ghani M, Migahid O, Megahed A, Adams J, Triplitt C, DeFronzo RA, Zirie M, Jayyousi A. Combination therapy with exenatide plus pioglitazone versus basal/bolus insulin in patients with poorly controlled type 2 diabetes on sulfonylurea plus metformin: The QATAR Study. Diabetes Care. 2017;40:325-331. Erratum: 2017 June 14 [Epub ahead of print].

DeFronzo RA. Banting Lecture. From the triumvirate to the ominous octet: A new paradigm for the treatment of type 2 diabetes mellitus. Diabetes. 2009;58:773-795.

Kaul S. Mitigating cardiovascular risk in type 2 diabetes with antidiabetes drugs: A review of principal cardiovascular outcome results of EMPA-REG OUTCOME, LEADER, and SUSTAIN-6 trials. Diabetes Care. 2017;40:821-831.

Neal B, Perkovic V, Mahaffey KW, de Zeeuw D, Fulcher G, Erondu N, Shaw W, Law G, Desai M, Matthews DR, for the CANVAS Program Collaborative Group. Canagliflozin and cardiovascular and renal events in type 2 diabetes. N Engl J Med. 2017 June 12 [Epub ahead of print].

 

Dr. Ralph Defronzo Interview

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