Neal D. Barnard

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.

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.

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.

Dietary and lifestyle guidelines for the prevention of Alzheimer's disease.

Risk of developing Alzheimers disease is increased by older age, genetic factors, and several medical risk factors. Studies have also suggested that dietary and lifestyle factors may influence risk, raising the possibility that preventive strategies may be effective. This body of research is incomplete. However, because the most scientifically supported lifestyle factors for Alzheimers disease are known factors for cardiovascular diseases and diabetes, it is reasonable to provide preliminary guidance to help individuals who wish to reduce their risk. At the International Conference on Nutrition and the Brain, Washington, DC, July 19-20, 2013, speakers were asked to comment on possible guidelines for Alzheimers disease prevention, with an aim of developing a set of practical, albeit preliminary, steps to be recommended to members of the public. From this discussion, 7 guidelines emerged related to healthful diet and exercise habits.

Vegetarian Diets and Blood Pressure: A Meta-analysis

IMPORTANCE Previous studies have suggested an association between vegetarian diets and lower blood pressure (BP), but the relationship is not well established. OBJECTIVE To conduct a systematic review and meta-analysis of controlled clinical trials and observational studies that have examined the association between vegetarian diets and BP. DATA SOURCES MEDLINE and Web of Science were searched for articles published in English from 1946 to October 2013 and from 1900 to November 2013, respectively. STUDY SELECTION All studies met the inclusion criteria of the use of (1) participants older than 20 years, (2) vegetarian diets as an exposure or intervention, (3) mean difference in BP as an outcome, and (4) a controlled trial or observational study design. In addition, none met the exclusion criteria of (1) use of twin participants, (2) use of multiple interventions, (3) reporting only categorical BP data, or (4) reliance on case series or case reports. DATA EXTRACTION AND SYNTHESIS Data collected included study design, baseline characteristics of the study population, dietary data, and outcomes. The data were pooled using a random-effects model. MAIN OUTCOMES AND MEASURES Net differences in systolic and diastolic BP associated with the consumption of vegetarian diets were assessed. RESULTS Of the 258 studies identified, 7 clinical trials and 32 observational studies met the inclusion criteria. In the 7 controlled trials (a total of 311 participants; mean age, 44.5 years), consumption of vegetarian diets was associated with a reduction in mean systolic BP (-4.8 mm Hg; 95% CI, -6.6 to -3.1; P < .001; I2 = 0; P = .45 for heterogeneity) and diastolic BP (-2.2 mm Hg; 95% CI, -3.5 to -1.0; P < .001; I2 = 0; P = .43 for heterogeneity) compared with the consumption of omnivorous diets. In the 32 observational studies (a total of 21,604 participants; mean age, 46.6 years), consumption of vegetarian diets was associated with lower mean systolic BP (-6.9 mm Hg; 95% CI, -9.1 to -4.7; P < .001; I2 = 91.4; P < .001 for heterogeneity) and diastolic BP (-4.7 mm Hg; 95% CI, -6.3 to -3.1; P < .001; I2 = 92.6; P < .001 for heterogeneity) compared with the consumption of omnivorous diets. CONCLUSIONS AND RELEVANCE Consumption of vegetarian diets is associated with lower BP. Such diets could be a useful nonpharmacologic means for reducing BP.

Effects of plant-based diets on plasma lipids.

Dyslipidemia is a primary risk factor for cardiovascular disease, peripheral vascular disease, and stroke. Current guidelines recommend diet as first-line therapy for patients with elevated plasma cholesterol concentrations. However, what constitutes an optimal dietary regimen remains a matter of controversy. Large prospective trials have demonstrated that populations following plant-based diets, particularly vegetarian and vegan diets, are at lower risk for ischemic heart disease mortality. The investigators therefore reviewed the published scientific research to determine the effectiveness of plant-based diets in modifying plasma lipid concentrations. Twenty-seven randomized controlled and observational trials were included. Of the 4 types of plant-based diets considered, interventions testing a combination diet (a vegetarian or vegan diet combined with nuts, soy, and/or fiber) demonstrated the greatest effects (up to 35% plasma low-density lipoprotein cholesterol reduction), followed by vegan and ovolactovegetarian diets. Interventions allowing small amounts of lean meat demonstrated less dramatic reductions in total cholesterol and low-density lipoprotein levels. In conclusion, plant-based dietary interventions are effective in lowering plasma cholesterol concentrations.

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.

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.

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.

Diet and acne: a review of the evidence

Pharmaceutical acne treatments are costly and have potentially severe side-effects. Adolescent acne is typically the result of clogged, infected, pilosebaceous follicles. Adults may experience fewer comedones and more inflammatory lesions. 1 Normally, sebum travels up the follicle to the skin surface. Hormones may increase sebum production and cause follicular cells to hyperproliferate and block the follicular opening, forming a comedo. 4 Complete follicle blockage results in closed comedones (i.e. “whiteheads”), whereas incomplete blockage results in open comedones (“blackheads”). Comedo formation typically occurs over the course of 2–3 weeks. Acne may manifest in the form of noninflammatory comedones, superficial inflammatory lesions (papules, pustules), and/or deeper inflammatory lesions (nodules, cysts). Inflammatory lesion formation occurs most commonly when Propionibacterium acnes colonizes the pilosebaceous unit, triggering follicular rupture and a neutrophil cascade. 5