Amber A. Green

A low-fat vegan diet and a conventional diabetes diet in the treatment of type 2 diabetes: a randomized, controlled, 74-wk clinical trial

BACKGROUND Low-fat vegetarian and vegan diets are associated with weight loss, increased insulin sensitivity, and improved cardiovascular health. OBJECTIVE We compared the effects of a low-fat vegan diet and conventional diabetes diet recommendations on glycemia, weight, and plasma lipids. DESIGN Free-living individuals with type 2 diabetes were randomly assigned to a low-fat vegan diet (n = 49) or a diet following 2003 American Diabetes Association guidelines (conventional, n = 50) for 74 wk. Glycated hemoglobin (Hb A(1c)) and plasma lipids were assessed at weeks 0, 11, 22, 35, 48, 61, and 74. Weight was measured at weeks 0, 22, and 74. RESULTS Weight loss was significant within each diet group but not significantly different between groups (-4.4 kg in the vegan group and -3.0 kg in the conventional diet group, P = 0.25) and related significantly to Hb A(1c) changes (r = 0.50, P = 0.001). Hb A(1c) changes from baseline to 74 wk or last available values were -0.34 and -0.14 for vegan and conventional diets, respectively (P = 0.43). Hb A(1c) changes from baseline to last available value or last value before any medication adjustment were -0.40 and 0.01 for vegan and conventional diets, respectively (P = 0.03). In analyses before alterations in lipid-lowering medications, total cholesterol decreased by 20.4 and 6.8 mg/dL in the vegan and conventional diet groups, respectively (P = 0.01); LDL cholesterol decreased by 13.5 and 3.4 mg/dL in the vegan and conventional groups, respectively (P = 0.03). CONCLUSIONS Both diets were associated with sustained reductions in weight and plasma lipid concentrations. In an analysis controlling for medication changes, a low-fat vegan diet appeared to improve glycemia and plasma lipids more than did conventional diabetes diet recommendations. Whether the observed differences provide clinical benefit for the macro- or microvascular complications of diabetes remains to be established. This trial was registered at clinicaltrials.gov as NCT00276939.

Changes in Nutrient Intake and Dietary Quality among Participants with Type 2 Diabetes Following a Low-Fat Vegan Diet or a Conventional Diabetes Diet for 22 Weeks

BACKGROUND Although vegan diets improve diabetes management, little is known about the nutrient profiles or diet quality of individuals with type 2 diabetes who adopt a vegan diet. OBJECTIVE To assess the changes in nutrient intake and dietary quality among participants following a low-fat vegan diet or the 2003 American Diabetes Association dietary recommendations. DESIGN A 22-week randomized, controlled clinical trial examining changes in nutrient intake and diet quality. SUBJECTS/SETTING Participants with type 2 diabetes (n=99) in a free-living setting. RESEARCH DESIGN AND METHODS Participants were randomly assigned to a low-fat vegan diet or a 2003 American Diabetes Association recommended diet. MAIN OUTCOME MEASURES Nutrient intake and Alternate Healthy Eating Index (AHEI) scores were collected at baseline and 22 weeks. STATISTICAL ANALYSES PERFORMED Between-group t tests were calculated for changes between groups and paired comparison t tests were calculated for changes within-group. Pearsons correlation assessed relationship of AHEI score to hemoglobin A1c and body weight changes. RESULTS Both groups reported significant decreases in energy, protein, fat, cholesterol, vitamin D, selenium, and sodium intakes. The vegan group also significantly reduced reported intakes of vitamin B-12 and calcium, and significantly increased carbohydrate, fiber, total vitamin A activity, beta carotene, vitamins K and C, folate, magnesium, and potassium. The American Diabetes Association recommended diet group also reported significant decreases in carbohydrate and iron, but reported no significant increases. The vegan group significantly improved its AHEI score (P<0.0001), while the American Diabetes Association recommended diet group did not (P=0.7218). The difference in AHEI score at 22 weeks between groups was significant (P<0.0001). With both groups combined, AHEI score was negatively correlated with both changes in hemoglobin A1c value (r=-0.24, P=0.016) and weight (r=-0.27, P=0.007). CONCLUSIONS Vegan diets increase intakes of carbohydrate, fiber, and several micronutrients, in contrast with the American Diabetes Association recommended diet. The vegan group improved its AHEI score whereas the American Diabetes Association recommended diet groups AHEI score remained unchanged.

A Low-Fat Vegan Diet Elicits Greater Macronutrient Changes, but Is Comparable in Adherence and Acceptability, Compared with a More Conventional Diabetes Diet among Individuals with Type 2 Diabetes

BACKGROUND Although therapeutic diets are critical to diabetes management, their acceptability to patients is largely unstudied. OBJECTIVE To quantify adherence and acceptability for two types of diets for diabetes. DESIGN Controlled trial conducted between 2004 and 2006. SUBJECTS/SETTING Individuals with type 2 diabetes (n=99) at a community-based research facility. Participants were randomly assigned to a diet following 2003 American Diabetes Association guidelines or a low-fat, vegan diet for 74 weeks. MAIN OUTCOME MEASURES Attrition, adherence, dietary behavior, diet acceptability, and cravings. STATISTICAL ANALYSES For nutrient intake and questionnaire scores, t tests determined between-group differences. For diet-acceptability measures, the related samples Wilcoxon sum rank test assessed within-group changes; the independent samples Mann-Whitney U test compared the diet groups. Changes in reported symptoms among the groups was compared using chi(2) for independent samples. RESULTS All participants completed the initial 22 weeks; 90% (45/50) of American Diabetes Association guidelines diet group and 86% (42/49) of the vegan diet group participants completed 74 weeks. Fat and cholesterol intake fell more and carbohydrate and fiber intake increased more in the vegan group. At 22 weeks, group-specific diet adherence criteria were met by 44% (22/50) of members of the American Diabetes Association diet group and 67% (33/49) of vegan-group participants (P=0.019); the American Diabetes Association guidelines diet group reported a greater increase in dietary restraint; this difference was not significant at 74 weeks. Both groups reported reduced hunger and reduced disinhibition. Questionnaire responses rated both diets as satisfactory, with no significant differences between groups, except for ease of preparation, for which the 22-week ratings marginally favored the American Diabetes Association guideline group. Cravings for fatty foods diminished more in the vegan group at 22 weeks, with no significant difference at 74 weeks. CONCLUSIONS Despite its greater influence on macronutrient intake, a low-fat, vegan diet has an acceptability similar to that of a more conventional diabetes diet. Acceptability appears to be no barrier to its use in medical nutrition therapy.

D2 Dopamine receptor Taq1A polymorphism, body weight, and dietary intake in type 2 diabetes

OBJECTIVE Certain D2 dopamine receptor Taq 1A genotypes (A1A1, A1A2) have been associated with obesity and substance abuse. We hypothesized that their presence would be associated with reduced efficacy of dietary interventions in individuals with type 2 diabetes. METHODS In the course of a randomized clinical trial in an outpatient research center in which 93 adults with type 2 diabetes were assigned to a low-fat vegan diet or a diet following 2003 American Diabetes Association guidelines for 74 wk, Taq 1A genotype was determined. Nutrient intake, body weight, and hemoglobin A1c (A1c) were measured over 74 wk. RESULTS The A1 allele was highly prevalent, occurring in 47% of white participants (n = 49), which was significantly higher than the 29% prevalence previously reported in non-diabetic whites (P = 0.01). The A1 allele was found in 55% of black participants (n = 44). Black participants with A1(+) genotypes had significantly greater mean body weight (11.2 kg heavier, P = 0.05) and greater intake of fat (P = 0.002), saturated fat (P = 0.01), and cholesterol (P = 0.02) compared with A2A2 (A1(-)) individuals; dietary changes during the study did not favor one genotype group. Among whites, baseline anthropometric and nutrient differences between gene groups were small. However, among whites in the vegan group, A1(+) individuals reduced fat intake (P = 0.04) and A1c (P = 0.01) significantly less than did A1(-) individuals. CONCLUSION The A1 allele appears to be highly prevalent among individuals with type 2 diabetes. Potential influences on diet, weight, and glycemic control merit further exploration.

A Multicomponent Intervention Reduces Body Weight and Cardiovascular Risk at a GEICO Corporate Site

Purpose. To determine whether a multicomponent nutrition intervention program at a corporate site reduces body weight and improves other cardiovascular risk factors in overweight individuals. Design. Prospective clinical intervention study. Subjects/Setting. Employees of the Government Employees Insurance Company (GEICO) (N = 113), aged 21 to 65 years, with a body mass index ≥ 25 kg/m2 and/or previous diagnosis of type 2 diabetes. Intervention. A 22-week intervention including a low-fat, vegan diet. Measures. Changes in body weight, anthropometric measures, blood pressure, lipid profile, and dietary intake. Analysis. Multivariate analyses of variance were calculated for clinical and nutrient measures, followed by univariate analyses of variance, to determine the significance of differences between groups in changes over time. Results. Intervention-group participants experienced greater weight changes compared with control-group participants (mean, – 5.1 [SE, .6] kg vs. + .1 [SE, .6] kg, p < .0001), as well as greater changes in waist circumference (mean, – 4.7 [SE, .6] cm vs. + .8 [SE, .6] cm, p < .0001) and waist:hip ratio (mean, – .006 [SE, .003] vs. + .014 [SE, .005], p = .0007). Weight loss of 5% of body weight was more frequently observed in the intervention group (48.5%) compared with the control group (11.1%) (χ2[1, N= 113] = 16.99, p < .0001). Conclusions. Among individuals volunteering for a 22-week worksite research study, an intervention using a low-fat, vegan diet effectively reduced body weight and waist circumference.

Decreases in Dietary Glycemic Index Are Related to Weight Loss among Individuals following Therapeutic Diets for Type 2 Diabetes

This study assessed the effect of changes in glycemic index (GI) and load (GL) on weight loss and glycated hemoglobin (HbA1c) among individuals with type 2 diabetes beginning a vegan diet or diet following the 2003 American Diabetes Association (ADA) recommendations. The study was a 22-wk, randomized trial of 99 participants with type 2 diabetes who were counseled to follow 1 of 2 diet treatments. GI and GL changes were assessed based on 3-d dietary records. The relationships between GI/GL and changes in weight and HbA1C were calculated. In an intention-to-treat analysis (n = 99), the vegan group reduced GI to a greater extent than the ADA group (P < 0.05), but GL was reduced further in the ADA than the vegan group (P < 0.001). GI predicted changes in weight (P = 0.001), adjusting for changes in fiber, carbohydrate, fat, alcohol, energy intake, steps per day, group, and demographics, such that for every point decrease in GI, participants lost ~0.2 kg (0.44 lb). GI was not a predictor for changes in HbA1C after controlling for weight loss (P = 0.33). Weight loss was a predictor of changes in HbA1C (P = 0.047). GL was not related to weight loss or changes in HbA1C. A low-GI diet appears to be one of the determinants of success of a vegan or ADA diet in reducing body weight among people with type 2 diabetes. The reduction of body weight, in turn, was predictive of decreasing HbA1C.

A worksite programme significantly alters nutrient intakes

OBJECTIVE To examine whether a worksite nutrition programme using a low-fat vegan diet could significantly improve nutritional intake. DESIGN At two corporate sites of the Government Employees Insurance Company, employees who were either overweight (BMI > or = 25 kg/m2) and/or had type 2 diabetes participated in a 22-week worksite-based dietary intervention study. SETTING At the intervention site, participants were asked to follow a low-fat vegan diet and participate in weekly group meetings that included instruction and group support (intervention group). At the control site, participants received no instruction (control group). At weeks 0 and 22, participants completed 3 d dietary records to assess energy and nutrient intake. SUBJECTS A total of 109 participants (sixty-five intervention and forty-four control). RESULTS In the intervention group, reported intake of total fat, trans fat, saturated fat and cholesterol decreased significantly (P < or = 0.001), as did energy and protein (P = 0.01), and vitamin B12 (P = 0.002), compared with the control group. Intake (exclusive of any use of nutritional supplements) of carbohydrate, fibre, vitamin C, magnesium and potassium increased significantly (P < or = 0.0001), as did that for beta-carotene (P = 0.0004), total vitamin A activity (P = 0.004), vitamin K (P = 0.01) and sodium (P = 0.04) in the intervention group, compared with the control group. CONCLUSIONS The present study suggests that a worksite vegan nutrition programme increases intakes of protective nutrients, such as fibre, folate and vitamin C, and decreases intakes of total fat, saturated fat and cholesterol.