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.

Detection of PhIP in grilled chicken entrées at popular chain restaurants throughout California

Heterocyclic amines (HCAs), compounds formed when meat is cooked at high temperatures particularly through pan frying, grilling, or barbequing, pose a potential carcinogenic risk to the public. It is unclear whether there is any level at which consumption of HCAs can be considered safe. Efforts to measure these compounds mainly include cooking studies under laboratory conditions and some measurement of home-cooked foods, but analysis of commercially cooked foods has been minimal. Attempts to estimate exposure of the public to these compounds must take into consideration dining outside the home, which could result in significant exposure for some individuals. We surveyed at least 9 locations each of 7 popular chain restaurants (McDonald's, Burger King, Chick-fil-A, Chili's, TGI Friday's, Outback Steakhouse, and Applebee's) in California, collecting one or two entrees from each location. Entrees were analyzed for 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) using high-performance liquid chromatography tandem mass spectrometry. All 100 samples contained PhIP. Concentrations were variable within and between entrees and ranged from 0.08 to 43.2 ng/g. When factoring in the weight of the entrees, absolute levels of PhIP reached over 1,000 ng for some entrees. Potential strategies for reducing exposure include the avoidance of meats cooked using methods that are known to form PhIP.

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.

Dairy and weight loss hypothesis: an evaluation of the clinical trials

This review evaluates evidence from clinical trials that assessed the effect of dairy product or calcium intake, with or without concomitant energy restriction, on body weight and adiposity. Of 49 randomized trials assessing the effect of dairy products or calcium supplementation on body weight, 41 showed no effect, two demonstrated weight gain, one showed a lower rate of gain, and five showed weight loss. Four of 24 trials report differential fat loss. Consequently, the majority of the current evidence from clinical trials does not support the hypothesis that calcium or dairy consumption aids in weight or fat loss.

Diet and survival after prostate cancer diagnosis

Prostate cancer is the most commonly diagnosed non-skin cancer in men in the United States. Among environmental factors, diet may play a particularly important role in its incidence, progression, and clinical outcome. This article reviews the findings of eight observational studies and 17 intervention or laboratory trials on the effect of plant-based diets and plant nutrients on both the progression and clinical outcome of prostate cancer as well as additional studies examining mechanisms that may explain dietary effects. While additional long-term therapeutic clinical trials are needed to further elucidate the role of diet, these early investigations suggest that a recommendation for individual patients to shift their diets toward plant foods may serve as an important component of the tertiary treatment of prostate cancer.

A two-year randomized weight loss trial comparing a vegan diet to a more moderate low-fat diet

OBJECTIVE

The objective was to assess the effect of a low-fat, vegan diet compared with the National Cholesterol Education Program (NCEP) diet on weight loss maintenance at 1 and 2 years.

RESEARCH METHODS AND PROCEDURES

Sixty-four overweight, postmenopausal women were randomly assigned to a vegan or NCEP diet for 14 weeks, and 62 women began the study. The study was done in two replications. Participants in the first replication (N = 28) received no follow-up support after the 14 weeks, and those in the second replication (N = 34) were offered group support meetings for 1 year. Weight and diet adherence were measured at 1 and 2 years for all participants. Weight loss is reported as median (interquartile range) and is the difference from baseline weight at years 1 and 2.

RESULTS

Individuals in the vegan group lost more weight than those in the NCEP group at 1 year [-4.9 (-0.5, -8.0) kg vs. -1.8 (0.8, -4.3); p < 0.05] and at 2 years [-3.1 (0.0, -6.0) kg vs. -0.8 (3.1, -4.2) kg; p < 0.05]. Those participants offered group support lost more weight at 1 year (p < 0.01) and 2 years (p < 0.05) than those without support. Attendance at meetings was associated with improved weight loss at 1 year (p < 0.001) and 2 years (p < 0.01).

DISCUSSION

A vegan diet was associated with significantly greater weight loss than the NCEP diet at 1 and 2 years. Both group support and meeting attendance were associated with significant weight loss at follow-up.

The role of diet in breast and prostate cancer survival

Cancer is a leading cause of death worldwide. Breast and prostate cancer are two of the most common malignancies and contribute significantly to the societal and economic burden of cancer. Various ethnic and racial groups are affected differently by overall cancer incidence and mortality. Racial disparities are evident for breast cancer survival and both prostate cancer incidence and survival. The reasons for differences in cancer incidence and survival are not entirely clear. However, diet plays an important role in cancer prevention and survival and may also be implicated in racial and ethnic disparities. Ecologic, case-control, cohort, and randomized, controlled studies have demonstrated the benefits of a low-fat, high-fiber diet for breast and prostate cancer survival. A plant-based diet, generally low in fat and high in fiber, may offer survival benefits for both breast and prostate cancer. Further research is required to establish effective interventions that promote healthy dietary choices that enhance cancer survival.

Development of a novel ELISA for human insulin using monoclonal antibodies produced in serum-free cell culture medium

OBJECTIVES

Development of an ELISA for human insulin that utilizes monoclonal antibodies (mAbs) produced in serum-free medium.

DESIGN AND METHODS

Insulin mAbs were produced in vitro by hybridomas in serum-free medium. A two-step ELISA was developed to replace bovine insulin (standard) and bovine serum albumin (assay buffer) with non-animal reagents.

RESULTS

The sensitivity of the insulin ELISA was 0.73 uU/mL with a dynamic range of 2-200 uU/mL. No cross-reactivity with either human C-peptide or human proinsulin was observed. The intra- and inter-assay CVs were <7%. The mean recovery of insulin added to plasma samples was between 102.2% and 105.7%. The mean linearity of dilution was between 93% and 110% of undiluted plasma samples. The animal serum-free (ASF) insulin ELISA showed no marked degradation of any kit component when stored at 37 degrees C for up to 7 days. Significantly higher fasting insulin levels were observed in overweight or obese subjects (n=12) compared to lean subjects (n=10, p<0.05). Feeding markedly increased fasting insulin levels in both lean (p<0.02) and overweight or obese (p<0.005) subjects. Excellent correlation was observed between insulin levels measured by ASF insulin ELISA and another CE marked insulin ELISA (y=1.06x-0.44, r=1.00, n=44).

CONCLUSIONS

This novel insulin ELISA provides precision and reliability equal to methods currently used in clinical research and serves as a guide for the development of other serum-free immunoassays.

A low-fat vegan diet improves glycemic control and cardiovascular risk factors in a randomized clinical trial in individuals with type 2 diabetes

OBJECTIVE

We sought to investigate whether a low-fat vegan diet improves glycemic control and cardiovascular risk factors in individuals with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Individuals with type 2 diabetes (n = 99) were randomly assigned to a low-fat vegan diet (n = 49) or a diet following the American Diabetes Association (ADA) guidelines (n = 50). Participants were evaluated at baseline and 22 weeks.

RESULTS

Forty-three percent (21 of 49) of the vegan group and 26% (13 of 50) of the ADA group participants reduced diabetes medications. Including all participants, HbA(1c) (A1C) decreased 0.96 percentage points in the vegan group and 0.56 points in the ADA group (P = 0.089). Excluding those who changed medications, A1C fell 1.23 points in the vegan group compared with 0.38 points in the ADA group (P = 0.01). Body weight decreased 6.5 kg in the vegan group and 3.1 kg in the ADA group (P < 0.001). Body weight change correlated with A1C change (r = 0.51, n = 57, P < 0.0001). Among those who did not change lipid-lowering medications, LDL cholesterol fell 21.2% in the vegan group and 10.7% in the ADA group (P = 0.02). After adjustment for baseline values, urinary albumin reductions were greater in the vegan group (15.9 mg/24 h) than in the ADA group (10.9 mg/24 h) (P = 0.013).

CONCLUSIONS

Both a low-fat vegan diet and a diet based on ADA guidelines improved glycemic and lipid control in type 2 diabetic patients. These improvements were greater with a low-fat vegan diet.

Acceptability of Soymilk as a Calcium-Rich Beverage in Elementary School Children

Dairy products are the main source of calcium in the National School Lunch Program. Children who avoid dairy products because of lactose intolerance or other concerns can benefit from the availability of another calcium-rich beverage in the National School Lunch Program. This study assessed whether elementary school children would select and consume calcium-fortified soymilk in school cafeterias and whether the addition of soymilk would increase the percentage of students selecting a calcium-rich beverage at lunch. The ratio of saturated fat to calcium consumed from calcium-rich beverages with and without the availability of soymilk was also determined. After 4 weeks of soymilk availability, 22.3% of students chose soymilk and consumed an average of 58% of each carton, whereas 77.6% chose dairy milk and consumed an average of 52.6%. Total calcium-rich beverage selection with lunch increased from 79% to 83.1%. Calcium consumption per gram of saturated fat consumed from calcium-rich beverages also rose from 194 mg to 237 mg with the addition of soymilk.

Serum-free hybridoma culture: ethical, scientific and safety considerations

Despite considerable progress in the development of cell culture techniques, including the development of the serum- and protein-free media that now routinely support hybridoma and mammalian cell growth, fetal bovine serum (FBS) supplemented media are still commonly used: a practice that raises ethical, scientific and safety concerns. The use of FBS in hybridoma culture media is examined here, with regards to the development and production of monoclonal antibodies (mAbs), and it is our recommendation that researchers adopt serum-free cell culture methods to reduce animal use in this area.

The effects of a low-fat, plant-based dietary intervention on body weight, metabolism, and insulin sensitivity

PURPOSE

This study investigated the effect of a low-fat, plant-based diet on body weight, metabolism, and insulin sensitivity, while controlling for exercise in free-living individuals.

SUBJECTS AND METHODS

In an outpatient setting, 64 overweight, postmenopausal women were randomly assigned to a low-fat, vegan diet or a control diet based on National Cholesterol Education Program guidelines, without energy intake limits, and were asked to maintain exercise unchanged. Dietary intake, body weight and composition, resting metabolic rate, thermic effect of food, and insulin sensitivity were measured at baseline and 14 weeks.

RESULTS

Mean +/- standard deviation intervention-group body weight decreased 5.8 +/- 3.2 kg, compared with 3.8 +/- 2.8 kg in the control group (P = .012). In a regression model of predictors of weight change, including diet group and changes in energy intake, thermic effect of food, resting metabolic rate, and reported energy expenditure, significant effects were found for diet group (P < .05), thermic effect of food (P < .05), and resting metabolic rate (P < .001). An index of insulin sensitivity increased from 4.6 +/- 2.9 to 5.7 +/- 3.9 (P = .017) in the intervention group, but the difference between groups was not significant (P = .17).

CONCLUSION

Adoption of a low-fat, vegan diet was associated with significant weight loss in overweight postmenopausal women, despite the absence of prescribed limits on portion size or energy intake.

Calcium, dairy products, and bone health in children and young adults: a reevaluation of the evidence

OBJECTIVE

Numerous nutrition policy statements recommend the consumption of 800 to 1500 mg of calcium largely from dairy products for osteoporosis prevention; however, the findings of epidemiologic and prospective studies have raised questions about the efficacy of the use of dairy products for the promotion of bone health. The objective of this study was to review existing literature on the effects of dairy products and total dietary calcium on bone integrity in children and young adults to assess whether evidence supports (1) current recommended calcium intake levels and (2) the suggestion that dairy products are better for promoting bone integrity than other calcium-containing food sources or supplements.

METHODS

A Medline (National Library of Medicine, Bethesda, MD) search was conducted for studies published on the relationship between milk, dairy products, or calcium intake and bone mineralization or fracture risk in children and young adults (1-25 years). This search yielded 58 studies: 22 cross-sectional studies; 13 retrospective studies; 10 longitudinal prospective studies; and 13 randomized, controlled trials.

RESULTS

Eleven of the studies did not control for weight, pubertal status, and exercise and were excluded. Ten studies were randomized, controlled trials of supplemental calcium, 9 of which showed modest positive benefits on bone mineralization in children and adolescents. Of the remaining 37 studies of dairy or unsupplemented dietary calcium intake, 27 studies found no relationship between dairy or dietary calcium intake and measures of bone health. In the remaining 9 reports, the effects on bone health are small and 3 were confounded by vitamin D intake from milk fortified with vitamin D. Therefore, in clinical, longitudinal, retrospective, and cross-sectional studies, neither increased consumption of dairy products, specifically, nor total dietary calcium consumption has shown even a modestly consistent benefit for child or young adult bone health.

CONCLUSION

Scant evidence supports nutrition guidelines focused specifically on increasing milk or other dairy product intake for promoting child and adolescent bone mineralization.

Blood Pressure Regulation and Vegetarian Diets

Hypertension affects approximately 50 million individuals in the United States and approximately 1 billion worldwide. Although heredity plays a role in blood pressure variability, diet and lifestyle exert considerable influence in blood pressure regulation. This report reviews the evidence of the relationship between a vegetarian diet and blood pressure regulation and presents data as to the putative mechanisms of action.

Laboratory routines cause animal stress

Eighty published studies were appraised to document the potential stress associated with three routine laboratory procedures commonly performed on animals: handling, blood collection, and orogastric gavage. We defined handling as any non-invasive manipulation occurring as part of routine husbandry, including lifting an animal and cleaning or moving an animal's cage. Significant changes in physiologic parameters correlated with stress (e.g., serum or plasma concentrations of corticosterone, glucose, growth hormone or prolactin, heart rate, blood pressure, and behavior) were associated with all three procedures in multiple species in the studies we examined. The results of these studies demonstrated that animals responded with rapid, pronounced, and statistically significant elevations in stress-related responses for each of the procedures, although handling elicited variable alterations in immune system responses. Changes from baseline or control measures typically ranged from 20% to 100% or more and lasted at least 30 min or longer. We interpret these findings to indicate that laboratory routines are associated with stress, and that animals do not readily habituate to them. The data suggest that significant fear, stress, and possibly distress are predictable consequences of routine laboratory procedures, and that these phenomena have substantial scientific and humane implications for the use of animals in laboratory research.

Effects of a low-fat vegan diet and a Step II diet on macro- and micronutrient intakes in overweight postmenopausal women

OBJECTIVE

This study investigated the nutrient intake of overweight postmenopausal women assigned to a low-fat vegan diet or a Step II diet.

METHODS

Fifty-nine overweight (body mass index, 26 to 44 kg/m2) postmenopausal women were randomly assigned to a self-selected low-fat vegan or a National Cholesterol Education Program Step II diet in a 14-wk controlled trial on weight loss and metabolism. Nutrient intake, which was measured per 1000 kcal, was the main outcome measure. Statistical analyses included within-group and between-group t tests examining changes associated with each diet.

RESULTS

Consumption of a low-fat vegan diet was associated with greater decreases in fat, saturated fat, protein, and cholesterol intakes and greater increases in carbohydrate, fiber, beta-carotene, and total vitamin A intakes than was a Step II diet. The low-fat vegan group also increased thiamin, vitamin B6, and magnesium intakes more than the Step II group, and both groups increased folic acid, vitamin C, and potassium intakes. If considering only food sources of micronutrients, the low-fat vegan group decreased vitamin D, vitamin B12, calcium, selenium, phosphorous, and zinc intakes compared with baseline. However, with incidental supplements included, decreases were evident only in phosphorous and selenium intakes. No micronutrient decreases were found in the Step II group.

CONCLUSIONS

Individuals on a low-fat vegan or Step II diet should take steps to meet the recommended intakes of vitamin D, vitamin K, folic acid, calcium, magnesium, and zinc. Individuals on a low-fat vegan diet should also ensure adequate intakes of vitamin B12, phosphorous, and selenium.

Acceptability of a Low-fat Vegan Diet Compares Favorably to a Step II Diet in a Randomized, Controlled Trial

PURPOSE

This study aimed to assess the acceptability of a low-fat vegan diet, as compared with a more typical fat-modified diet, among overweight and obese adults.

METHODS

Through newspaper advertisements, 64 overweight, postmenopausal women were recruited, 59 of whom completed the study. The participants were assigned randomly to a low-fat vegan diet or, for comparison, to a National Cholesterol Education Program Step II (NCEP) diet. At baseline and 14 weeks later, dietary intake, dietary restraint, disinhibition, and hunger, as well as the acceptability and perceived benefits and adverse effects of each diet were assessed.

RESULTS

Dietary restraint increased in the NCEP group (P <.001), indicating a greater subjective sense of constraint with regard to diet requirements, but was unchanged in the vegan group. Disinhibition and hunger scores fell in each group (P <.001 and P <.01, respectively). The acceptability of both diets was high, although the vegan group participants rated their diet as less easy to prepare than their usual diets (P <.05) and the NCEP participants foresaw continuation of their assigned diet to be more difficult than continuation of their baseline diets (P <.05). There were no between-group differences on any acceptability measures.

CONCLUSIONS

The acceptability of a low-fat vegan diet is high and not demonstrably different from that of a more moderate low-fat diet among well-educated, postmenopausal women in a research environment.

Type 2 diabetes and the vegetarian diet

Based on what is known of the components of plant-based diets and their effects from cohort studies, there is reason to believe that vegetarian diets would have advantages in the treatment of type 2 diabetes. At present there are few data on vegetarian diets in diabetes that do not in addition have weight loss or exercise components. Nevertheless, the use of whole-grain or traditionally processed cereals and legumes has been associated with improved glycemic control in both diabetic and insulin-resistant individuals. Long-term cohort studies have indicated that whole-grain consumption reduces the risk of both type 2 diabetes and cardiovascular disease. In addition, nuts (eg, almonds), viscous fibers (eg, fibers from oats and barley), soy proteins, and plant sterols, which may be part of the vegetarian diet, reduce serum lipids. In combination, these plant food components may have a very significant impact on cardiovascular disease, one of the major complications of diabetes. Furthermore, substituting soy or other vegetable proteins for animal protein may also decrease renal hyperfiltration, proteinuria, and renal acid load and in the long term reduce the risk of developing renal disease in type 2 diabetes. The vegetarian diet, therefore, contains a portfolio of natural products and food forms of benefit for both the carbohydrate and lipid abnormalities in diabetes. It is anticipated that their combined use in vegetarian diets will produce very significant metabolic advantages for the prevention and treatment of diabetes and its complications.

The consumer cost of calcium from food and supplements

Nutritional authorities encourage consumers to include calcium-rich foods in their daily diets. However, consumer purchases are driven not only by health considerations and dietary preferences, but also by cost. This study assessed the cost of calcium from a wide variety of food sources, as well as supplements, based on retail prices in Seattle, San Francisco, Raleigh, NewYork City, and Washington, D.C., while controlling for seasonal variation. Costs were adjusted based on calcium absorption fractions. Calcium carbonate supplements emerged as the least expensive source of calcium, at roughly one-third the cost of the least expensive food source of calcium. The least expensive food sources of calcium were Total cereal, skim milk, and calcium-fortified orange juice from frozen concentrate. This information is useful for dietitians, health professionals, and consumers in meeting calcium requirements on a budget.