Does diet quality matter? A secondary analysis of a randomized clinical trial

This secondary analysis assessed the association of a plant-based index (PDI), healthful (hPDI), and unhealthful (uPDI), with weight loss in overweight adults. Participants (n = 244) were randomly assigned to a vegan (n = 122) or control group (n = 122) for 16 weeks. Three-day dietary records were analyzed and PDI indices were calculated. A repeated measure ANOVA was used for statistical analysis. All three scores increased in the vegan group; the effect sizes were: PDI +10.6 (95% CI +8.6 to +12.6; p < 0.001); hPDI +10.9 (95% CI +8.4 to +13.4; p < 0.001); and uPDI +5.4 (95% CI +3.4 to +7.4; p < 0.001). The change in all three scores significantly correlated with change in body weight: PDI (r = -0.40; p < 0.001); hPDI (r = -0.37; p < 0.001); and uPDI (r = -0.21; p = 0.002). These findings suggest that minimizing the consumption of animal products and oil may be an effective weight loss strategy in overweight adults. ClinicalTrials.gov number, NCT02939638.

A dietary intervention for postmenopausal hot flashes: A potential role of gut microbiome. An exploratory analysis

OBJECTIVE

This study examined the role of gut microbiome changes in mediating the effects of a dietary intervention on the frequency and severity of postmenopausal vasomotor symptoms METHODS: Postmenopausal women (n = 84) reporting ≥2 moderate-to-severe hot flashes daily were randomly assigned, in 2 successive cohorts, to an intervention including a low-fat, vegan diet and cooked soybeans (½ cup [86 g] daily) or to stay on their usual diet. Over a 12-week period, frequency and severity of hot flashes were recorded with a mobile application. In a subset of 11 women, gut microbiome was analyzed at baseline and after 12 weeks of the dietary intervention (low-fat vegan diet with soybeans), using deep shotgun metagenomic sequencing. Differences in the microbiome between baseline and 12 weeks were assessed by comparing alpha diversity with Wilcoxon signed rank tests, beta diversity with permanovaFL, and taxon abundance with Wilcoxon signed rank tests. Pearson correlations were used to assess the association between changes in hot flashes and gut bacteria.

RESULTS

In the subset for which microbiome testing was done, total hot flashes decreased by 95 % during the dietary intervention (p = 0.007); severe hot flashes disappeared (from 0.6 to 0.0/day; p = 0.06); and moderate-to-severe hot flashes decreased by 96 % (p = 0.01). Daytime and nighttime hot flashes were reduced by 96 % (p = 0.01) and 94 % (p = 0.004), respectively. Alpha and beta diversity did not significantly differ in the intervention group between baseline and 12 weeks. Two families (Enterobacteriaceae and Veillonellaceae), 5 genera (Erysipelatoclostridium, Fusicatenibacter, Holdemanella, Intestinimonas, and Porphyromonas), and 6 species (Clostridium asparagiforme, Clostridium innocuum, Bacteroides thetaiotaomicron, Fusicatenibacter saccharivorans, Intestinimonas butyriciproducens, Prevotella corporis, and Streptococcus sp.) were differentially abundant, but after correction for multiple comparisons, these differences were no longer significant. Changes in the relative abundance of Porphyromonas and Prevotella corporis were associated with the reduction in severe day hot flashes both unadjusted (r = 0.61; p = 0.047; and r = 0.69; p = 0.02), respectively), and after adjustment for changes in body mass index (r = 0.63; p = 0.049; and r = 0.73; p = 0.02), respectively). Changes in relative abundance of Clostridium asparagiforme were associated with the reduction in total severe hot flashes (r = 0.69; p = 0.019) and severe night hot flashes (r = 0.82; p = 0.002) and the latter association remained significant after adjustment for changes in body mass index (r = 0.75; p = 0.01).

CONCLUSIONS

This exploratory analysis revealed potential associations between changes in vasomotor symptoms in response to a diet change and changes in the gut microbiome. Larger randomized clinical trials are needed to investigate these findings.

Vegan Diet and Food Costs Among Adults With Overweight: A Secondary Analysis of a Randomized Clinical Trial

This secondary analysis of a randomized clinical trial investigates the effects of a vegan diet on total food costs per day.

Dietary advanced glycation products and their associations with insulin sensitivity and body weight: A 16-week randomized clinical trial

Background

Evidence suggests that changes in advanced glycation end-products (AGEs) may influence body weight. Previous studies have focused on cooking methods as the primary way how to reduce the dietary AGEs but little is known about the effects of a change in diet composition.

Objective

The aim of this study was to assess the effects of a low-fat plant-based diet on dietary AGEs and test the association with body weight, body composition, and insulin sensitivity.

Methods

Participants who were overweight (n = 244) were randomly assigned to an intervention (low-fat plant-based) (n = 122) or control group (n = 122) for 16 weeks. Before and after the intervention period, body composition was measured by dual X-ray absorptiometry. Insulin sensitivity was assessed with the predicted insulin sensitivity index (PREDIM). Three-day diet records were analyzed using the Nutrition Data System for Research software and dietary AGEs were estimated, using a database. Repeated measure ANOVA was used for statistical analysis.

Results

Dietary AGEs decreased in the intervention group by 8768 ku/day on average (95% -9611 to -7925; p < 0.001), compared with the control group (-1608; 95% CI -2709 to -506; p = 0.005; treatment effect -7161 ku/day [95% CI -8540 to -5781]; Gxt, p < 0.001). Body weight decreased by 6.4 kg in the intervention group, compared with 0.5 kg in the control group (treatment effect -5.9 kg [95% CI -6.8 to -5.0]; Gxt, p < 0.001), largely due to a reduction in fat mass, notably visceral fat. PREDIM increased in the intervention group (treatment effect +0.9 [95% CI + 0.5 to +1.2]; p < 0.001). Changes in dietary AGEs correlated with changes in body weight (r = +0.41; p < 0.001), fat mass (r = +0.38; p < 0.001), visceral fat (r = +0.23; p < 0.001), and PREDIM (r = -0.28; p < 0.001), and remained significant even after adjustment for changes in energy intake (r = +0.35; p < 0.001 for body weight; r = +0.34; p < 0.001 for fat mass; r = +0.15; p = 0.03 for visceral fat; and r = -0.24; p < 0.001 for PREDIM).

Conclusions

Dietary AGEs decreased on a low-fat plant-based diet, and this decrease was associated with changes in body weight, body composition, and insulin sensitivity, independent of energy intake. These findings demonstrate positive effects of qualitative dietary changes on dietary AGEs and cardiometabolic outcomes.

Clinical Trial Registry Number

NCT02939638.

Dietary advanced glycation end-products and postmenopausal hot flashes: A post-hoc analysis of a 12-week randomized clinical trial

OBJECTIVE

Postmenopausal hot flashes are associated with an increased risk of cardiovascular disease and diabetes. Because dietary advanced glycation end-products (AGEs) may act as endocrine disruptors, this study examined the potential association of modifications to the intake of dietary AGEs with the frequency and severity of postmenopausal hot flashes.

METHODS

Postmenopausal women (n = 84) reporting ≥2 moderate-to-severe hot flashes daily were randomly assigned to either the intervention group or the control group. The former were asked to follow a low-fat, vegan diet, including cooked soybeans (1/2 cup [86 g]/day) for 12 weeks, and the latter continued their usual diets for 12 weeks. Frequency and severity of hot flashes were recorded with a mobile application. Three-day diet records were analyzed using the Nutrition Data System for Research software and dietary AGEs were estimated, using a database. Seventy-one participants completed the whole study and 63 provided complete hot flash and dietary data for the AGEs analysis (n = 31 in the intervention and n = 24 in the control group). Pearson correlations were used to assess the association between changes in hot flashes and dietary AGEs.

RESULTS

Dietary AGEs decreased in the intervention group by 73 %, that is by 5509 ku/day on average (95 % -7009 to -4009; p < 0.001), compared with the control group (+458; 95 % CI -835 to +1751; p = 0.47; treatment effect -5968 ku/day [95 % CI -7945 to -3991]; Gxt, p < 0.001). Severe hot flashes decreased by 92 % (p < 0.001) and moderate-to-severe hot flashes decreased by 88 % in the intervention group (p < 0.001). Changes in dietary AGEs correlated with changes in severe (r = +0.39; p = 0.002) and moderate hot flashes (r = +0.34; p = 0.009) and remained significant after adjustment for changes in energy intake (r = +0.45; p < 0.001; and r = +0.37; p = 0.004, respectively) and changes in body mass index (r = +0.37; p = 0.004; and r = +0.27; p = 0.04, respectively). The reduction in dietary AGEs required to achieve a predicted reduction in hot flashes by 1/day was 6933 ku/day for severe and 4366 ku/day for moderate-to-severe hot flashes.

CONCLUSIONS

The reduction in dietary AGEs with a low-fat plant-based diet was associated with a significant reduction in the frequency of severe and moderate-to-severe postmenopausal hot flashes, independent of changes in energy intake and weight loss. Plant-based diets could be used not only to alleviate vasomotor symptoms in postmenopausal women, but also to reduce other health risks associated with AGEs.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04587154.

Nutrition in the prevention and treatment of endometriosis: A review

Endometriosis is characterized by the presence of endometrial tissues outside the uterine lining, typically on the external surface of the uterus, the ovaries, fallopian tubes, abdominal wall, or intestines. The prevalence of endometriosis in North America, Australia, and Europe is ~1-5% in women of reproductive age. Treatment options for endometriosis are limited. While over-the-counter medications may be used to reduce acute pain, hormonal treatments are common and may interfere with fertility. In more severe cases, laparoscopic excision procedures and even hysterectomies are used to treat the pain associated with endometriosis. Nutritional interventions may be helpful in the prevention and treatment of endometriosis and associated pain. Reducing dietary fat and increasing dietary fiber have been shown to reduce circulating estrogen concentrations, suggesting a potential benefit for individuals with endometriosis, as it is an estrogen-dependent disease. Meat consumption is associated with greater risk of developing endometriosis. Anti-inflammatory properties of plant-based diets may benefit women with endometriosis. Additionally, seaweed holds estrogen-modulating properties that have benefitted postmenopausal women and offers potential to reduce estradiol concentrations in pre-menopausal women. Furthermore, consumption of vitamin D has been shown to reduce endometrial pain via increased antioxidant capacity and supplementation with vitamins C and E significantly reduced endometriosis symptoms, compared with placebo. More randomized clinical trials are needed to elucidate the role of diet in endometriosis.

Controversial Dietary Patterns: A High Yield Primer for Clinicians

In cardiology clinic visits, the discussion of optimal dietary patterns for prevention and management of cardiovascular disease is usually very limited. Herein, we explore the benefits and risks of various dietary patterns, including intermittent fasting, low carbohydrate, Paleolithic, whole food plant-based diet, and Mediterranean dietary patterns within the context of cardiovascular disease to empower clinicians with the evidence and information they need to maximally benefit their patients.

The Role of Nutrition in COVID-19: Taking a Lesson from the 1918 H1N1 Pandemic

In looking for solutions to the COVID-19 pandemic, important lessons come from the H1N1 influenza pandemic of 1918-1919. During the H1N1 influenza pandemic, the soldiers had better outcomes than the civilian populations, but the best outcomes were reported by a Seventh-day Adventist seminary, where a plant-based diet was provided. The diet has been described as including grains, fruits, nuts, and vegetables. A few clinical trials have also assessed the role of nutrition in COVID-19. One study with almost six hundred thousand participants showed that those with a high consumption of fruits and vegetables had a reduced risk of COVID-19 of any severity by 9% and a reduced risk of severe COVID-19 by 41%. Another study in healthcare workers who were frequently exposed to COVID-19 in their clinical practice has demonstrated that those who reported being on a plant-based diet had a 73% lower risk of moderate-to-severe COVID-19. Based on the lessons from 1918 and the recent nutrition research in COVID-19, it seems plausible that a healthful plant-based diet may be a powerful tool to decrease the risk of severe COVID-19 and should be promoted as one of the public health safety measures.

A Randomized, Crossover Trial of a Nutritional Intervention for Rheumatoid Arthritis

To investigate the effects of a dietary intervention on arthritis pain and disease severity, 44 adults previously diagnosed with rheumatoid arthritis were randomly assigned to a Diet phase (vegan diet for 4 weeks, elimination of additional foods for 3 weeks, and then reintroduction of the eliminated foods individually over 9 weeks) or a Supplement (placebo) phase for 16 weeks. After a 4-week washout, they then switched to the opposite phase. The Disease Activity Score-28 (DAS28) decreased from 4.5 to 2.5 (P < .001) in the Diet phase and from 3.2 to 2.9 (P = .41) in the Supplement phase (between-group P = .01). The mean number of swollen joints decreased from 7.0 to 3.3 in the Diet phase (P = .03) and increased from 4.7 to 5 in the Supplement phase (P = .63; between-group P = .047).

In a subanalysis excluding individuals who increased medications during the study, DAS28 decreased 1.9 points in the Diet phase (P = .003) and .4 points in the Supplement phase (P = .27; between-group P = .04). In a further subanalysis limited to participants making no medication changes, DAS28 decreased 1.5 points in the Diet phase (P = .009) and .3 points in the Supplement phase (P = .40, between-group P = .11). We conclude that the dietary intervention was associated with symptomatic improvements. TRIAL REGISTRATION: Clinicaltrials.gov NCT01544101, NCT01700881, NCT03417648, and NCT03580681

Universal Meals: A Novel Program to Provide Healthful Nutrition to Diverse Communities

Healthcare professionals recommending dietary changes to patients often find that institutional settings—businesses, universities, long-term care facilities, correctional institutions, among others—may not provide the healthful foods that healthcare professionals recommend. Moreover, such institutions encounter an increasing diversity of dietary restrictions, based on allergies, intolerances, religious mandates, or other reasons, that may be challenging to satisfy. To address these issues, experts in health, dietetics, culinary arts, religion, and ethics developed a simple set of guidelines that aim to meet the widest possible range of dietary needs. Three culinary teams then used these guidelines to create “Universal Meals”—simple recipes that were then adapted to larger production sizes for institutional use. The healthfulness of representative sets of meals drawn from these recipes was assessed using the Alternative Healthy Eating Index-2010 and found to be superior to that of a meal pattern based on National Health and Nutrition Examination Survey data.

Trending Nutrition Controversies #3: Top Controversies in 2021

Each year, patients are bombarded with diverging and even contradictory reports concerning the impact of certain additives, foods, and nutrients on cardiovascular health and its risk factors. Accordingly, this third review of nutrition controversies examines the impact of artificial sweeteners, cacao, soy, plant-based meats, nitrates, and meats from grass compared to grain-fed animals on cardiovascular and other health outcomes with the goal of optimizing clinician-led diet counseling.

Nutrition for Hospital Workers During a Crisis: Effect of a Plant-Based Dietary Intervention on Cardiometabolic Outcomes and Quality of Life in Healthcare Employees During the COVID-19 Pandemic

The study tested the effects of a vegan diet on cardiometabolic outcomes and quality of life among healthcare employees during the COVID-19 pandemic. Overweight hospital employees were enrolled and randomly assigned (in a 1:1 ratio) to an intervention group, which was asked to follow a low-fat vegan diet, or a control group, asked to make no diet changes. However, due to COVID-19 disruptions, all participants remained on their usual diets from March to June (12 weeks), creating a de facto control period, and all (n = 12) started the vegan diet with online classes in June, which continued for 12 weeks. Nine participants completed all final assessments. A crossover ANOVA was used for statistical analysis of differences in cardiovascular health during the control period and during the intervention. Despite the ongoing crisis, body weight decreased (treatment effect −5.7 kg [95% CI −9.7 to −1.7]; P = .01); fasting plasma glucose decreased (−11.4 mg/dL [95% CI −18.8 to −4.1]; P = .007); total and LDL-cholesterol decreased (−30.7 mg/dL [95% CI −53.8 to −7.5]; P = .02; and −24.6 mg/dL [−44.8 to −4.3]; P = .02, respectively); diastolic blood pressure decreased (−8.5 mm Hg [95% CI −16.3 to −.7]; P = .03); and quality of life increased (P = .005) during the intervention period, compared with the control period. A vegan diet improved cardiometabolic outcomes and quality of life in healthcare workers at the height of the COVID-19 pandemic.

Ketogenic Diets and Chronic Disease: Weighing the Benefits Against the Risks

Very-low-carbohydrate ketogenic diets have been long been used to reduce seizure frequency and more recently have been promoted for a variety of health conditions, including obesity, diabetes, and liver disease. Ketogenic diets may provide short-term improvement and aid in symptom management for some chronic diseases. Such diets affect diet quality, typically increasing intake of foods linked to chronic disease risk and decreasing intake of foods found to be protective in epidemiological studies. This review examines the effects of ketogenic diets on common chronic diseases, as well as their impact on diet quality and possible risks associated with their use. Given often-temporary improvements, unfavorable effects on dietary intake, and inadequate data demonstrating long-term safety, for most individuals, the risks of ketogenic diets may outweigh the benefits.

The Women's Study for the Alleviation of Vasomotor Symptoms (WAVS): a randomized, controlled trial of a plant-based diet and whole soybeans for postmenopausal women

OBJECTIVE

This study aimed to assess the effects of the combination of a low-fat plant-based diet and soybeans on the frequency and severity of menopausal hot flashes.

METHODS

Postmenopausal women (n = 38) reporting two or more hot flashes/day were randomly assigned to a low-fat, vegan diet, including ½ cup (86 g) of cooked soybeans daily, or to no diet changes for 12 weeks. Frequency and severity of hot flashes were recorded using a mobile application, and vasomotor, psychosocial, physical, and sexual symptoms were assessed using the Menopause-Specific Quality of Life Questionnaire. Significance was assessed using t-tests (continuous outcomes) and chi-squared/McNemar tests (binary outcomes).

RESULTS

Total hot flashes decreased 79% in the intervention group (P < 0.001) and 49% in the control group (P = 0.002; between-group P = 0.01). Moderate-to-severe hot flashes decreased 84% in the intervention group (P < 0.001) and 42% in the control group P = 0.009; between-group P = 0.01). From 0 to 12 weeks, 59% (10/17) of intervention-group participants reported becoming free of moderate and severe hot flashes (P = 0.002). There was no change in this variable in the control group (between-group P < 0.001). The Menopause-Specific Quality of Life Questionnaire revealed significantly greater reductions in the intervention group in vasomotor (P < 0.0001), psychosocial (P = 0.04), physical (P < 0.002), and sexual (P = 0.01) domains.

CONCLUSIONS

The combination of a low-fat, vegan diet and whole soybeans was associated with reduced frequency and severity of hot flashes and improved quality of life in vasomotor, psychosocial, physical, and sexual domains in postmenopausal women. During the 12-week study period, the majority of intervention-group participants became free of moderate-to-severe hot flashes.

Perspective: Plant-Based Eating Pattern for Type 2 Diabetes Prevention and Treatment: Efficacy, Mechanisms, and Practical Considerations

A plant-based eating pattern is associated with a reduced risk of developing type 2 diabetes and is highly effective in its treatment. Diets that emphasize whole grains, vegetables, fruits, and legumes and exclude animal products improve blood glucose concentrations, body weight, plasma lipid concentrations, and blood pressure and play an important role in reducing the risk of cardiovascular and microvascular complications. This article reviews scientific evidence on the effects of plant-based diets for the prevention and treatment of type 2 diabetes. The mechanisms by which plant-based diets improve body weight, insulin sensitivity, and β-cell function are described. Practical considerations including education, nutrition adequacy, and adjusting medications will enhance the success of patients who have diabetes.

A plant-based diet in overweight adults in a 16-week randomized clinical trial: The role of dietary acid load

BACKGROUND

Evidence suggests that changes in dietary acid load may influence body weight, body composition, and insulin sensitivity.

METHODS

Participants (n = 244) were randomly assigned to an intervention (vegan) (n = 122) or control group (n = 122) for 16 weeks. Before and after the intervention period, body composition was measured by dual X-ray absorptiometry. Insulin resistance was assessed with the Homeostasis Model Assessment (HOMA-IR) index and predicted insulin sensitivity index (PREDIM). Repeated measure ANOVA was used for statistical analysis.

RESULTS

Potential Renal Acid Load (PRAL) and Net Endogenous Acid Production (NEAP) decreased significantly in the vegan group with no change in the control group (treatment effect -24.7 mEq/day [95% CI -30.2 to -19.2]; p < 0.001; and -23.8 mEq/day [95% CI -29.6 to -18.0]; p < 0.001, respectively). Body weight decreased by 6.4 kg in the vegan group, compared with 0.5 kg in the control group (treatment effect -5.9 kg [95% CI -6.8 to -5.0]; Gxt, p < 0.001), largely due to a reduction in fat mass and visceral fat. HOMA-IR index decreased and PREDIM increased in the vegan group. After adjustment for energy intake, changes in PRAL and NEAP correlated positively with changes in body weight (r = +0.37; p < 0.001; and r = +0.37; p < 0.001, respectively), fat mass (r = +0.32; p < 0.001; and r = +0.32; p < 0.001, respectively), visceral fat (r = +0.19; p = 0.006; and r = +0.15; p = 0.03, respectively), and HOMA (r = +0.17; p = 0.02; and r = +0.20; p = 0.006, respectively), and negatively with changes in PREDIM (r = -0.22; p = 0.002; and r = -0.27; p < 0.001, respectively).

CONCLUSION

Dietary acid load as part of a plant-based diet was associated with changes in body weight, body composition, and insulin sensitivity, independent of energy intake. Mechanistic explanations suggest that the relationship may be causal.

TRIAL REGISTRATION

ClinicalTrials.gov number, NCT03698955.

The role of nutrition in asthma prevention and treatment

Asthma is a chronic respiratory condition characterized by airway inflammation and hyperreactivity. Prevalence has continued to rise in recent decades as Western dietary patterns have become more pervasive. Evidence suggests that diets emphasizing the consumption of plant-based foods might protect against asthma development and improve asthma symptoms through their effects on systemic inflammation, oxidation, and microbial composition. Additionally, increased fruit and vegetable intake, reduced animal product consumption, and weight management might mediate cytokine release, free radical damage, and immune responses involved in the development and course of asthma. The specific aim of this review paper is to examine the current literature on the associations between dietary factors and asthma risk and control in children and adults. Clinical trials examining the mechanism(s) by which dietary factors influence asthma outcomes are necessary to identify the potential use of nutritional therapy in the prevention and management of asthma.

A Mediterranean Diet and Low-Fat Vegan Diet to Improve Body Weight and Cardiometabolic Risk Factors: A Randomized, Cross-over Trial

Objective: Evidence suggests that both Mediterranean and vegan diets improve body weight and cardiometabolic risk factors, but their relative efficacy has not been compared in a randomized trial.Methods: In a randomized crossover trial, 62 overweight adults were randomly assigned to a Mediterranean or vegan diet for a 16-week period. Body weight, plasma lipids, blood pressure, and body composition (dual X-ray absorptiometry) were measured. Secondary measures included insulin resistance (Homeostasis Model Assessment, HOMA-IR), oral glucose insulin sensitivity (OGIS), and predicted insulin sensitivity (PREDIM) indices. Thereafter, participants were asked to return to their baseline diets for 4 weeks, after which they began the opposite diet for 16 weeks. The same parameters were measured before and after this 2^nd 16-week period.Results: Overall net weight changes were 0.0 (Mediterranean) and -6.0 kg (vegan), (treatment effect -6.0 kg [95% CI -7.5 to -4.5]; p < 0.001). HOMA-IR decreased and OGIS increased on the vegan diet with no significant change on the Mediterranean diet (treatment effect -0.7 [95% CI, -1.8 to +0.4]; p = 0.21; and +35.8 mL/min/m² [95% CI, +13.2 to +58.3]; p = 0.003, respectively). PREDIM did not change significantly in either group. Among participants with no medication changes, total and LDL-cholesterol decreased 18.7 mg/dL (0.5 mmol/L) and 15.3 mg/dL (0.4 mmol/L), respectively, on the vegan diet, compared with no significant change on the Mediterranean diet (treatment effect -15.6 [-24.6 to -6.6]; p = 0.001 and -14.8 [-23.5 to -6.2]; p = 0.001, respectively); systolic and diastolic blood pressure decreased 9.3 and 7.3 mmHg on the Mediterranean diet, compared with 3.4 and 4.1 mmHg on the vegan diet (treatment effect +5.9 [95% CI +1.0 to +10.9]; p = 0.02; and +1.8 [95% CI -4.6 to +8.1]; p = 0.58, respectively).Conclusions: A low-fat vegan diet improved body weight, lipid concentrations, and insulin sensitivity, both from baseline and compared with a Mediterranean diet. Blood pressure decreased on both diets, more on the Mediterranean diet.Clinical trial registration: ClinicalTrials.gov number, NCT03698955 https://clinicaltrials.gov/ct2/show/NCT03698955?term=NCT03698955&draw=2&rank=1.

Blood Type Is Not Associated with Changes in Cardiometabolic Outcomes in Response to a Plant-Based Dietary Intervention

BACKGROUND

Risk of cardiovascular disease is lower in individuals with blood type O and increased in individuals with blood type A, compared with those in other blood groups. However, little evidence is available regarding whether individuals with different blood types benefit from different diet recommendations.

OBJECTIVE

As part of a larger intervention trial using a low-fat vegan diet, this study ascertained whether changes in cardiometabolic outcomes were associated with ABO blood type.

DESIGN

A secondary analysis among intervention-group participants in a 16-week randomized clinical trial.

PARTICIPANTS/SETTING

In a larger study of overweight individuals randomly assigned to follow a low-fat vegan diet or to make no diet changes for 16 weeks, ABO blood typing was conducted on 68 intervention-group participants.

INTERVENTION

Intervention-group participants were asked to follow a low-fat vegan diet and attend weekly educational classes to aid in diet adherence.

MAIN OUTCOME MEASURES

Body weight, fat mass, visceral fat volume, blood lipid levels, fasting plasma glucose levels, and glycated hemoglobin concentrations.

STATISTICAL ANALYSES PERFORMED

Student t tests compared participants with blood type A to all other participants, and individuals with blood type O to all other participants.

RESULTS

There were no significant differences in any outcome between individuals of blood type A and all other participants, or between individuals of blood type O and all other participants. Mean body weight change was -5.7 kg for blood type A participants and -7.0 kg for all other participants (P = 0.09), and was -7.1 kg for type O participants and -6.2 kg for all other participants (P = 0.33). Mean total cholesterol decreased 17.2 mg/dL in the type A group and 18.3 mg/dL for all other participants (P = 0.90), and decreased 17.4 mg/dL among type O participants and 18.4 mg/dL for all other participants (P = 0.89).

CONCLUSIONS

Blood type was not associated with the effects of a plant-based diet on body weight, body fat, plasma lipid concentrations, or glycemic control.

Effect of a Low-Fat Vegan Diet on Body Weight, Insulin Sensitivity, Postprandial Metabolism, and Intramyocellular and Hepatocellular Lipid Levels in Overweight Adults: A Randomized Clinical Trial

IMPORTANCE

Excess body weight and insulin resistance lead to type 2 diabetes and other major health problems. There is an urgent need for dietary interventions to address these conditions.

OBJECTIVE

To measure the effects of a low-fat vegan diet on body weight, insulin resistance, postprandial metabolism, and intramyocellular and hepatocellular lipid levels in overweight adults.

DESIGN, SETTING, AND PARTICIPANTS

This 16-week randomized clinical trial was conducted between January 2017 and February 2019 in Washington, DC. Of 3115 people who responded to flyers in medical offices and newspaper and radio advertisements, 244 met the participation criteria (age 25 to 75 years; body mass index of 28 to 40) after having been screened by telephone.

INTERVENTIONS

Participants were randomized in a 1:1 ratio. The intervention group (n = 122) was asked to follow a low-fat vegan diet and the control group (n = 122) to make no diet changes for 16 weeks.

MAIN OUTCOMES AND MEASURES

At weeks 0 and 16, body weight was assessed using a calibrated scale. Body composition and visceral fat were measured by dual x-ray absorptiometry. Insulin resistance was assessed with the homeostasis model assessment index and the predicted insulin sensitivity index (PREDIM). Thermic effect of food was measured by indirect calorimetry over 3 hours after a standard liquid breakfast (720 kcal). In a subset of participants (n = 44), hepatocellular and intramyocellular lipids were quantified by proton magnetic resonance spectroscopy. Repeated measure analysis of variance was used for statistical analysis.

RESULTS

Among the 244 participants in the study, 211 (87%) were female, 117 (48%) were White, and the mean (SD) age was 54.4 (11.6) years. Over the 16 weeks, body weight decreased in the intervention group by 5.9 kg (95% CI, 5.0-6.7 kg; P < .001). Thermic effect of food increased in the intervention group by 14.1% (95% CI, 6.5-20.4; P < .001). The homeostasis model assessment index decreased (-1.3; 95% CI, -2.2 to -0.3; P < .001) and PREDIM increased (0.9; 95% CI, 0.5-1.2; P < .001) in the intervention group. Hepatocellular lipid levels decreased in the intervention group by 34.4%, from a mean (SD) of 3.2% (2.9%) to 2.4% (2.2%) (P = .002), and intramyocellular lipid levels decreased by 10.4%, from a mean (SD) of 1.6 (1.1) to 1.5 (1.0) (P = .03). None of these variables changed significantly in the control group over the 16 weeks. The change in PREDIM correlated negatively with the change in body weight (r = -0.43; P < .001). Changes in hepatocellular and intramyocellular lipid levels correlated with changes in insulin resistance (both r = 0.51; P = .01).

CONCLUSIONS AND RELEVANCE

A low-fat plant-based dietary intervention reduces body weight by reducing energy intake and increasing postprandial metabolism. The changes are associated with reductions in hepatocellular and intramyocellular fat and increased insulin sensitivity.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02939638.

Children and adults should avoid consuming animal products to reduce risk for chronic disease: YES

The consumption of animal products exposes humans to saturated fat, cholesterol, lactose, estrogens, and pathogenic microorganisms, while displacing fiber, complex carbohydrates, antioxidants, and other components needed for health. In the process, consumption of animal products increases the risk for cardiovascular disease, cancer, diabetes, obesity, and other disorders. This dietary pattern also promotes the growth of unhealthful gut bacteria, fostering, among other things, the production of trimethylamine N-oxide, a proinflammatory compound associated with cardiovascular and neurological diseases. When omnivorous individuals change to a plant-based diet, diet quality as measured by the Alternate Healthy Eating Index improves, and the risk of these health problems diminishes. Planning for nutrient adequacy is important with any diet. However, a diet based on vegetables, fruits, whole grains, and legumes, supplemented with vitamin B-12, is nutritionally superior to diets including animal products and is healthful for children and adults.

Children and adults should avoid consuming animal products to reduce the risk for chronic disease: Debate Consensus

The present debate outlined opposing views regarding the role of animal products in human diets. The YES position argues that the health benefits and safety of plant-based diets have been clearly established by consistent findings of randomized trials and observational studies; that animal products skew the diet toward saturated fat, excess protein, cholesterol, lactose, and exogenous hormones; and that vulnerable populations are better nourished by vegetables, fruits, legumes, and whole grains than by striated muscle and cow milk. In contrast, the NO position asserts that animal foods are not only benign but are also key elements of the human omnivore diet, facilitating the global challenge of adequate essential nutrition. This view holds that the portrayal of animal foods as unhealthy is not supported by the evidence and that a restrictive vegan diet decreases nutritional flexibility and robustness, increasing risk for vulnerable population groups. Points of agreement and controversy were identified, as well as opportunities for further studies.

Children and adults should avoid consuming animal products to reduce risk for chronic disease: NO

Excessive attention to the animal versus plant binary food choice reflects society's moral views on eating right. To claim that avoidance of animal products is required to prevent chronic disease is not supported by evidence, makes little sense from an evolutionary perspective, and distracts policy makers from common-sense approaches to achieve adequate nutrition. Animal products provide highly bioavailable nutrients, some of which are not easily obtained from plants, and can play a key role in meeting the nutritional challenges of populations in both high- and low-income countries. This role goes beyond the need for protein and relates to vitamins, minerals, and numerous often-overlooked nutrients, such as long-chain fatty acids, taurine, and choline. Restrictive dietary prescriptions that exclude animal products complicate the quest for optimal nutrition by undermining dietary diversity and flexibility, and by introducing a dependency on fortification and supplementation. Thus, a vegan diet may put the general population at increased risk of poor nutrition, a problem of particular concern for those with special nutritional requirements.

Effects of a Low-Fat Vegan Diet on Gut Microbiota in Overweight Individuals and Relationships with Body Weight, Body Composition, and Insulin Sensitivity. A Randomized Clinical Trial

Diet modulates gut microbiota and plays an important role in human health. The aim of this study was to test the effect of a low-fat vegan diet on gut microbiota and its association with weight, body composition, and insulin resistance in overweight men and women. We enrolled 168 participants and randomly assigned them to a vegan (n = 84) or a control group (n = 84) for 16 weeks. Of these, 115 returned all gut microbiome samples. Gut microbiota composition was assessed using uBiome Explorer™ kits. Body composition was measured using dual energy X-ray absorptiometry. Insulin sensitivity was quantified with the predicted clamp-derived insulin sensitivity index from a standard meal test. Repeated measure ANOVA was used for statistical analysis. Body weight decreased in the vegan group (treatment effect -5.9 kg [95% CI, -7.0 to -4.9 kg]; p < 0.001), mainly due to a reduction in fat mass (-3.9 kg [95% CI, -4.6 to -3.1 kg]; p < 0.001) and in visceral fat (-240 cm3 [95% CI, -345 to -135 kg]; p < 0.001). PREDIcted M, insulin sensitivity index (PREDIM) increased in the vegan group (treatment effect +0.83 [95% CI, +0.48 to +1.2]; p < 0.001). The relative abundance of Faecalibacterium prausnitzii increased in the vegan group (+5.1% [95% CI, +2.4 to +7.9%]; p < 0.001) and correlated negatively with changes in weight (r = -0.24; p = 0.01), fat mass (r = -0.22; p = 0.02), and visceral fat (r = -0.20; p = 0.03). The relative abundance of Bacteroides fragilis decreased in both groups, but less in the vegan group, making the treatment effect positive (+18.9% [95% CI, +14.2 to +23.7%]; p < 0.001), which correlated negatively with changes in weight (r = -0.44; p < 0.001), fat mass (r = -0.43; p < 0.001), and visceral fat (r = -0.28; p = 0.003) and positively with PREDIM (r = 0.36; p < 0.001), so a smaller reduction in Bacteroides fragilis was associated with a greater loss of body weight, fat mass, visceral fat, and a greater increase in insulin sensitivity. A low-fat vegan diet induced significant changes in gut microbiota, which were related to changes in weight, body composition, and insulin sensitivity in overweight adults, suggesting a potential use in clinical practice.

Barriers, Opportunities, and Challenges in Addressing Disparities in Diet-Related Cardiovascular Disease in the United States

In the United States, cardiovascular disease (CVD) is the leading cause of death and disability. Suboptimal diet quality is responsible for a greater percentage of CVD-related morbidity and mortality than any other modifiable risk factor. Further troubling are the stark racial/ethnic and socioeconomic disparities in diet quality. This represents a major public health concern that urgently requires a coordinated effort to better characterize the barriers to healthy dietary practices in population groups disproportionally affected by CVD and poor diet quality to inform multifaceted approaches at the government (policy), community environment, sociocultural, and individual levels. This paper reviews the barriers, opportunities, and challenges involved in shifting population behaviors, especially in underserved populations, toward healthy dietary practices. It is imperative that public health policies address the social determinants of nutrition more intensively than previously in order to significantly decrease CVD on a population-wide basis.

Successful Implementation of Healthful Nutrition Initiatives into Hospitals

Poor dietary quality is a leading contributor to mortality in the United States, and to most cardiovascular risk factors. By providing education on lifestyle changes and, specifically, dietary changes, hospitals have the opportunity to use the patient experience as a "teachable moment." The food options provided to inpatients and outpatients can be a paradigm for patients to follow upon discharge from the hospital. There are hospitals in the United States that are showcasing novel ways to increase awareness of optimal dietary patterns and can serve as a model for hospitals nationwide.

Industry Funding and Cholesterol Research: A Systematic Review

The effect of diet on blood cholesterol concentrations has become controversial. We assessed whether industry-funded studies were more likely than non-industry-funded studies to report conclusions that were not supported by their objective findings. PubMed and Cochrane Central Register of Controlled Trials searches through March 8, 2019, yielded 211 relevant articles. The percentage of industry-funded studies increased from 0% in the 1950s to 60% for 2010 tp 2019 (P < .001). Of 94 non-industry-funded intervention studies for which the effect of egg ingestion on cholesterol concentrations could be determined, net cholesterol increases were reported in 88 (93%) studies (51% statistically significant, 21% not significant, 21% significance not reported). Among 59 industry-funded intervention studies, net cholesterol increases were reported in 51 (86%) studies (34% statistically significant, 39% not significant, and 14% significance not reported). No studies reported significant cholesterol decreases. Nonsignificant net cholesterol decreases were reported by 6 (6%) non-industry-funded and 8 (14%) industry-funded studies. However, 49% of industry-funded intervention studies reported conclusions that were discordant with study results (ie, net cholesterol increases were described as favorable in the articles' stated conclusions), compared with 13% of non-industry-funded studies. Readers, editors, and the public should remain alert to funding sources in interpreting study findings and conclusions.

Nutrition Interventions in Rheumatoid Arthritis: The Potential Use of Plant-Based Diets. A Review

Rheumatoid arthritis (RA), a chronic inflammatory autoimmune disease, affects roughly 1% of the world's population. RA pathogenesis remains unclear, but genetic factors account for 50–60% of the risk while the remainder might be linked to modifiable factors, such as infectious diseases, tobacco smoking, gut bacteria, and nutrition. Dietary triggers may play an inciting role in the autoimmune process, and a compromised intestinal barrier may allow food components or microorganisms to enter the blood stream, triggering inflammation. In addition, excessive body weight may affect pharmacotherapy response and the likelihood of disease remission, as well as the risk of disease mortality. Evidence suggests that changes in diet might play an important role in RA management and remission. Several studies have shown improvements in RA symptoms with diets excluding animal products. Studies have also shown that dietary fiber found in these plant-based foods can improve gut bacteria composition and increase bacterial diversity in RA patients, thus reducing their inflammation and joint pain. Although some of the trigger foods in RA patients are individualized, a vegan diet helps improve symptoms by eliminating many of these foods. This review examines the potential role of a plant-based diet in mediating RA symptoms. Further research is needed to test the effectiveness of plant-based diets on joint pain, inflammation, and quality of life in patients with RA.

Crohn's Disease Remission with a Plant-Based Diet: A Case Report

Crohn’s disease (CD) is a form of chronic inflammatory bowel disease (IBD). The etiology of CD is thought to be multi-factorial; genetic factors, dietary and environmental exposures, immune events, and dysfunction of the gut microbiome are all though to play a role. The prevalence of CD is increasing globally and is higher in countries with a Westernized diet and lifestyle. Several human trials have demonstrated that plant-based dietary therapies may have utility in both the treatment of acute CD flares and the maintenance of remission. This case study describes a young adult male with newly diagnosed CD who failed to enter clinical remission despite standard medical therapy. After switching to a diet based exclusively on grains, legumes, vegetables, and fruits, he entered clinical remission without need for medication and showed no signs of CD on follow-up colonoscopy.

The Thermic Effect of Food: A Review

Two-thirds of U.S. adults are overweight. There is an urgent need for effective methods for weight management. A potentially modifiable component of energy expenditure is the thermic effect of food (TEF), the increase in the metabolic rate that occurs after a meal. Evidence suggests that TEF is increased by larger meal sizes (as opposed to frequent small meals), intake of carbohydrate and protein (as opposed to dietary fat), and low-fat plant-based diets. Age and physical activity may also play roles in TEF. The effects of habitual diet, meal timing, and other factors remain to be clarified. Further research into the factors that affect TEF may lead to better treatment methods for improved weight management. Key teaching points Measurement of the thermic effect of food. Physiological determinants of the thermic effect of food. The effects of meal variations on postprandial thermogenesis. Effect of age and physical activity on the thermic effect of food.

The Effects of Vegetarian and Vegan Diets on Gut Microbiota

The difference in gut microbiota composition between individuals following vegan or vegetarian diets and those following omnivorous diets is well documented. A plant-based diet appears to be beneficial for human health by promoting the development of more diverse and stable microbial systems. Additionally, vegans and vegetarians have significantly higher counts of certain Bacteroidetes-related operational taxonomic units compared to omnivores. Fibers (that is, non-digestible carbohydrates, found exclusively in plants) most consistently increase lactic acid bacteria, such as Ruminococcus, E. rectale, and Roseburia, and reduce Clostridium and Enterococcus species. Polyphenols, also abundant in plant foods, increase Bifidobacterium and Lactobacillus, which provide anti-pathogenic and anti-inflammatory effects and cardiovascular protection. High fiber intake also encourages the growth of species that ferment fiber into metabolites as short-chain fatty acids (SCFAs), including acetate, propionate, and butyrate. The positive health effects of SCFAs are myriad, including improved immunity against pathogens, blood-brain barrier integrity, provision of energy substrates, and regulation of critical functions of the intestine. In conclusion, the available literature suggests that a vegetarian/vegan diet is effective in promoting a diverse ecosystem of beneficial bacteria to support both human gut microbiome and overall health. This review will focus on effects of different diets and nutrient contents, particularly plant-based diets, on the gut microbiota composition and production of microbial metabolites affecting the host health.

Fat Quantity and Quality, as Part of a Low-Fat, Vegan Diet, Are Associated with Changes in Body Composition, Insulin Resistance, and Insulin Secretion. A 16-Week Randomized Controlled Trial

Macronutrient composition of the diet influences the development of obesity and insulin resistance. The aim of this study was to assess the role of dietary fat quantity and fatty acid composition in body composition, insulin resistance, and insulin secretion. An open parallel randomized trial design was used. Overweight participants (n = 75) were randomized to follow a low-fat vegan (n = 38) or control diet (n = 37) for 16 weeks. Dual X-ray absorptiometry was used to measure body composition. Insulin resistance was assessed with the Homeostasis Model Assessment (HOMA-IR) index. Insulin secretion was assessed after stimulation with a liquid breakfast (Boost Plus, Nestle, Vevey, Switzerland). Self-reported 3-day diet records were used to assess dietary intake. A linear regression model was used to test the relationship between fat intake and body composition, insulin resistance, and insulin secretion. Changes in fat intake expressed as percent of total energy consumed correlated positively with changes in fat mass (r = 0.52; p < 0.001; and 0.347; p = 0.006, respectively), even after adjustment for changes in body-mass index (BMI) and energy intake (0.33; p = 0.01). Decreased intakes of C18:0 (r = 0.37, p = 0.004) and CLA-trans-10-cis12 (r = 0.40, p = 0.002), but increased intake of C18:2 (r = −0.40, p = 0.002) and C18:3 (p = −0.36, p = 0.006), were associated with a decrease in HOMA-IR, independent on changes in BMI and energy intake. The main fatty acids associated with changes in fasting insulin secretion were C12:0 (r = −0.31, p = 0.03), and TRANS 16:1 (r = −0.33, p = 0.02), both independent on changes in BMI and energy intake. Our findings demonstrate that, in the context of a low-fat vegan diet, decreased intake of saturated and trans fats and increased relative content of polyunsaturated fatty acids, particularly linoleic and α-linolenic acids, are associated with decreased fat mass and insulin resistance, and enhanced insulin secretion.

A plant-based diet in overweight individuals in a 16-week randomized clinical trial: metabolic benefits of plant protein

Background and objectives

A plant-based diet is an effective strategy in the treatment of obesity. In this 16-week randomized clinical trial, we tested the effect of a plant-based diet on body composition and insulin resistance. As a part of this trial, we investigated the role of plant protein on these outcomes.

Subjects and methods

Overweight participants (n = 75) were randomized to follow a plant-based (n = 38) or a control diet (n = 37). Dual X-ray Absorptiometry assessed body composition, Homeostasis Model Assessment (HOMA-IR) assessed insulin resistance, and a linear regression model was used to test the relationship between protein intake, body composition, and insulin resistance.

Results

The plant-based vegan diet proved to be superior to the control diet in improving body weight, fat mass, and insulin resistance markers. Only the vegan group showed significant reductions in body weight (treatment effect −6.5 [95% CI −8.9 to −4.1] kg; Gxt, p < 0.001), fat mass (treatment effect −4.3 [95% CI −5.4 to −3.2] kg; Gxt, p < 0.001), and HOMA-IR (treatment effect −1.0 [95% CI −1.2 to −0.8]; Gxt, p = 0.004). The decrease in fat mass was associated with an increased intake of plant protein and decreased intake of animal protein (r = -0.30, p = 0.011; and r = +0.39, p = 0.001, respectively). In particular, decreased % leucine intake was associated with a decrease in fat mass (r = +0.40; p < 0.001), in both unadjusted and adjusted models for changes in BMI and energy intake. In addition, decreased % histidine intake was associated with a decrease in insulin resistance (r = +0.38; p = 0.003), also independent of changes in BMI and energy intake.

Conclusions

These findings provide evidence that plant protein, as a part of a plant-based diet, and the resulting limitation of leucine and histidine intake are associated with improvements in body composition and reductions in both body weight and insulin resistance.

Association between plant-based diets and plasma lipids: a systematic review and meta-analysis

Context

Although a recent meta-analysis of randomized controlled trials showed that adoption of a vegetarian diet reduces plasma lipids, the association between vegetarian diets and long-term effects on plasma lipids has not been subjected to meta-analysis.

Objective

The aim was to conduct a systematic review and meta-analysis of observational studies and clinical trials that have examined associations between plant-based diets and plasma lipids.

Data Sources

MEDLINE, Web of Science, and the Cochrane Central Register of Controlled Trials were searched for articles published in English until June 2015.

Study Selection

The literature was searched for controlled trials and observational studies that investigated the effects of at least 4 weeks of a vegetarian diet on plasma lipids.

Data Extraction

Two reviewers independently extracted the study methodology and sample size, the baseline characteristics of the study population, and the concentrations and variance measures of plasma lipids. Mean differences in concentrations of plasma lipids between vegetarian and comparison diet groups were calculated. Data were pooled using a random-effects model.

Results

Of the 8385 studies identified, 30 observational studies and 19 clinical trials met the inclusion criteria (N = 1484; mean age, 48.6 years). Consumption of vegetarian diets was associated with lower mean concentrations of total cholesterol (−29.2 and −12.5 mg/dL, P < 0.001), low-density lipoprotein cholesterol (−22.9 and −12.2 mg/dL, P < 0.001), and high-density lipoprotein cholesterol (−3.6 and −3.4 mg/dL, P < 0.001), compared with consumption of omnivorous diets in observational studies and clinical trials, respectively. Triglyceride differences were −6.5 (P = 0.092) in observational studies and 5.8 mg/dL (P = 0.090) in intervention trials.

Conclusions

Plant-based diets are associated with decreased total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol, but not with decreased triglycerides.

Systematic Review Registration

PROSPERO number CRD42015023783. Available at: https://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42015023783.

A dietary intervention for chronic diabetic neuropathy pain: a randomized controlled pilot study

Background:

Diabetic neuropathy is a common and often debilitating condition for which available treatments are limited. Because a low-fat plant-based diet has been shown to improve glycemic control in individuals with type 2 diabetes, we hypothesized that such a diet would reduce painful symptoms of diabetic neuropathy.

Methods:

In this 20-week pilot study, individuals with type 2 diabetes and painful diabetic neuropathy were randomly assigned to two groups. The intervention group was asked to follow a low-fat, plant-based diet, with weekly classes for support in following the prescribed diet, and to take a vitamin B12 supplement. The control group was asked to take the same vitamin B12 supplement, but received no other intervention. At baseline, midpoint and 20 weeks, clinical, laboratory and questionnaire data were collected. Questionnaires included an analog ‘worst pain' scale, Michigan Neuropathy Screening Instrument, global impression scale, Short Form McGill Pain Questionnaire, Neuropathy Total Symptom Score, a weekly pain diary and Norfolk Quality of Life Questionnaire.

Results:

After 20 weeks, body weight change with the intervention was −6.4 kg (95% confidence interval (CI) −9.4 to −3.4, P<0.001) in an effect size analysis. Electrochemical skin conductance in the foot improved by an average of 12.4 microseimens (95% CI 1.2–23.6, P=0.03) with the intervention in an effect size analysis. The between-group difference in change in pain, as measured by the McGill pain questionnaire, was −8.2 points (95% CI −16.1 to −0.3, P=0.04). Michigan Neuropathy Screening Instrument questionnaire score change was −1.6 points (95% CI −3.0 to −0.2, P=0.03).

Conclusions:

Improvements were seen in some clinical and pain measures. This pilot study suggests the potential value of a plant-based diet intervention, including weekly support classes, for treating painful diabetic neuropathy.

Vegetarian diets and glycemic control in diabetes: a systematic review and meta-analysis

INTRODUCTION

Previous studies have suggested an association between vegetarian diets and improvements in glycemic control in diabetes, although this relationship is not well established. No meta-analysis of these studies has been performed.

METHODS

To conduct a systematic review and meta-analysis of controlled clinical trials examining the association between vegetarian diets and glycemic control in type 2 diabetes.

DATA SOURCE

The electronic databases Medline, Web of Science, Excerpta Medica Database (EMBASE), and Cochrane Central Register of Controlled Trials were searched for articles published in any language through December 9, 2013.

STUDY SELECTION

The following criteria were used for study inclusion: (I) age of participants >20 years; (II) vegetarian diet as intervention; (III) mean difference in hemoglobin A1c (HbA1c) and/or fasting blood glucose levels used as outcomes; and (IV) controlled trials, duration ≥4 weeks. Exclusion criteria were: (I) not an original investigation; (II) duplicate samples; (III) diabetes other than type 2; (IV) multiple interventions; and (V) uncontrolled studies.

DATA EXTRACTION AND SYNTHESIS

The data collected included study design, baseline population characteristics, dietary data, and outcomes. Data were pooled using a random-effects model.

MAIN OUTCOMES AND MEASURES

Differences in HbA1c and fasting blood glucose levels associated with vegetarian diets were assessed.

RESULTS

Of 477 studies identified, six met the inclusion criteria (n=255, mean age 42.5 years). Consumption of vegetarian diets was associated with a significant reduction in HbA1c [-0.39 percentage point; 95% confidence interval (CI), -0.62 to -0.15; P=0.001; I(2)=3.0; P for heterogeneity =0.389], and a non-significant reduction in fasting blood glucose concentration (-0.36 mmol/L; 95% CI, -1.04 to 0.32; P=0.301; I(2)=0; P for heterogeneity =0.710), compared with consumption of comparator diets.

CONCLUSIONS

Consumption of vegetarian diets is associated with improved glycemic control in type 2 diabetes. PROSPERO registration number is CRD42013004370.

Nutrition intervention for migraine: a randomized crossover trial

Background

Limited evidence suggests that dietary interventions may offer a promising approach for migraine. The purpose of this study was to determine the effects of a low-fat plant-based diet intervention on migraine severity and frequency.

Methods

Forty-two adult migraine sufferers were recruited from the general community in Washington, DC, and divided randomly into two groups. This 36-week crossover study included two treatments: dietary instruction and placebo supplement. Each treatment period was 16 weeks, with a 4-week washout between. During the diet period, a low-fat vegan diet was prescribed for 4 weeks, after which an elimination diet was used. Participants were assessed at the beginning, midpoint, and end of each period. Significance was determined using student’s t-tests.

Results

Worst headache pain in last 2 weeks, as measured by visual analog scale, was initially 6.4/10 cm (SD 2.1 cm), and declined 2.1 cm during the diet period and 0.7 cm during the supplement period (p=0.03). Average headache intensity (0–10 scale) was initially 4.2 (SD 1.4) per week, and this declined by 1.0 during the diet period and by 0.5 during the supplement period (p=0.20). Average headache frequency was initially 2.3 (SD 1.8) per week, and this declined by 0.3 during the diet period and by 0.4 during the supplement period (p=0.61). The Patient’s Global Impression of Change showed greater improvement in pain during the diet period (p<0.001).

Conclusions

These results suggest that a nutritional approach may be a useful part of migraine treatment, but that methodologic issues necessitate further research.

Trial registration

Clinicaltrials.gov, NCT01699009 and NCT01547494.