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

Adoption of a Short-Term (4-Week) Vegan Diet as Part of 'Veganuary' Significantly Reduces Saturated Fatty Acid (SFA), Cholesterol, B12, and Iodine Intake in Omnivorous Individuals-An Observational Study

Global veganism campaigns like 'Veganuary' have gained popularity. We conducted an observational study to assess the impact of a 4-week vegan diet during 'Veganuary' on nutrient intake, status, knowledge, and motivations for veganism. Data were collected before and after 'Veganuary', using Food Frequency Questionnaires (FFQs) to estimate dietary intake. Micronutrient knowledge and motivation were assessed through questionnaires. A total of 154 UK adults aged 18-60 years (2019: n81; 2020: n73) participated. Groups were vegetarians and omnivores committed to a 4-week vegan diet during 'Veganuary'. Control groups were vegans and omnivores who did not transition. Short-term vegan diets significantly decreased intake of iodine, B12, cholesterol, and saturated fatty acids (SFAs) in omnivores. Micronutrient knowledge was low, and motivation for veganism varied. Short-term vegan diets reduce macro- and micronutrient intake in omnivores. Veganuary participants could benefit from nutritional guidance or supplementation. Attention is required for UK micronutrient intake and knowledge. Motivations for vegan pledges may influence diets, warranting further research.

The Role of Diet and Nutrition in Allergic Diseases

Allergic diseases are a set of chronic inflammatory disorders of lung, skin, and nose epithelium characterized by aberrant IgE and Th2 cytokine-mediated immune responses to exposed allergens. The prevalence of allergic diseases, including asthma, allergic rhinitis, and atopic dermatitis, has increased dramatically worldwide in the past several decades. Evidence suggests that diet and nutrition play a key role in the development and severity of allergic diseases. Dietary components can differentially regulate allergic inflammation pathways through host and gut microbiota-derived metabolites, therefore influencing allergy outcomes in positive or negative ways. A broad range of nutrients and dietary components (vitamins A, D, and E, minerals Zn, Iron, and Se, dietary fiber, fatty acids, and phytochemicals) are found to be effective in the prevention or treatment of allergic diseases through the suppression of type 2 inflammation. This paper aims to review recent advances in the role of diet and nutrition in the etiology of allergies, nutritional regulation of allergic inflammation, and clinical findings about nutrient supplementation in treating allergic diseases. The current literature suggests the potential efficacy of plant-based diets in reducing allergic symptoms. Further clinical trials are warranted to examine the potential beneficial effects of plant-based diets and anti-allergic nutrients in the prevention and management of allergic diseases.

Association between plant-based diets and metabolic syndrome in obese adults from Iran: a cross-sectional study

BACKGROUND

Metabolic syndrome (MetS) is a common chronic disease with several complications. Given that, studies on the association of plant-based diet indices (PDIs) with risk of MetS among adults with obesity, are limited, we aimed to examine the association between PDIs (including overall PDI, healthy PDI (hPDI), unhealthy PDI (uPDI)) and MetS in Iranian adults with obesity.

METHODS

In Tabriz, Iran, a total of 347 adults between the ages of 20 and 50 participated in this cross-sectional research study. We created an overall PDI, hPDI, and uPDI from validated semi-quantitative food-frequency questionnaire (FFQ) data. To investigate the association between hPDI, overall PDI, uPDI, and MetS and its components, a binary logistic regression analysis was performed.

RESULTS

The average age was 40.78 ± 9.23 years, and the average body mass index was 32.62 ± 4.80 kg/m². There was no significant association between overall PDI (OR: 0.87; 95% CI: 0.54-1.47), hPDI (OR: 0.82; 95% CI: 0.48-1.40), and uPDI (OR: 0.83; 95% CI: 0.87-2.46) with MetS, even after adjustment for confounders. Moreover, our findings showed that participants with the highest adherence to uPDI had a higher chance of hyperglycemia (OR: 2.50; 95% CI: 1.13-5.52). Also, this association was significant in the first (OR: 2.51; 95% CI: 1.04-6.04) and second (OR: 2.58; 95% CI: 1.05-6.33) models, after controlling for covariates. However, in both adjusted and crude models, we did not find a significant association between hPDI and PDI scores and MetS components such as high triglyceride, high waist circumference, low High-density lipoprotein cholesterol, raised blood pressure, and hyperglycemia. Moreover, those in the top tertile of uPDI had higher fasting blood sugar and insulin levels when compared with those in the first tertile, and subjects in the last tertile of hPDI compared with participants in the first tertile had lower weight, waist-to-hip ratio, and fat-free mass.

CONCLUSION

We found a direct significant association between uPDI and odds of hyperglycemia in the whole population of study. Future large-scale, prospective studies on PDIs and the MetS are necessary to confirm these findings.

Changes in Food and Nutrient Intake and Diet Quality on a Low-Fat Vegan Diet Are Associated with Changes in Body Weight, Body Composition, and Insulin Sensitivity in Overweight Adults: A Randomized Clinical Trial

BACKGROUND

Consuming different food groups and nutrients can have differential effects on body weight, body composition, and insulin sensitivity.

OBJECTIVE

The aim was to identify how food group, nutrient intake, and diet quality change relative to usual-diet controls after 16 weeks on a low-fat vegan diet and what associations those changes have with changes in body weight, body composition, and measures of metabolic health.

DESIGN

Secondary analysis of a randomized clinical trial conducted between October 2016 and December 2018 in four replications.

PARTICIPANTS/SETTING

Participants included in this analysis were 219 healthy, community-based adults in the Washington, DC, area, with a body mass index (BMI) between 28 and 40 kg/m², who were randomly assigned to follow either a low-fat vegan diet or make no diet changes.

INTERVENTION

A low-fat, vegan diet deriving approximately 10% of energy from fat, with weekly classes including dietary instruction, group discussion, and education on the health effects of plant-based nutrition. Control group participants continued their usual diets.

MAIN OUTCOME MEASURES

Changes in food group intake, macro- and micronutrient intake, and dietary quality as measured by Alternate Healthy Eating Index-2010 (AHEI-2010), analyzed from 3-day diet records, and associations with changes in body weight, body composition, and insulin sensitivity were assessed.

STATISTICAL ANALYSES PERFORMED

A repeated measure analysis of variance (ANOVA) model that included the factors group, subject, and time, was used to test the between-group differences throughout the 16-week study. Interaction between group and time (Gxt) was calculated for each variable. Within each diet group, paired comparison t-tests were calculated to identify significant changes from baseline to 16 weeks. Spearman correlations were calculated for the relationship between changes in food group intake, nutrient intake, AHEI-2010 score, and changes in body weight, body composition, and insulin sensitivity. The relative contribution of food groups and nutrients to weight loss was evaluated using linear regression.

RESULTS

Fruit, vegetable, legume, meat alternative, and whole grain intake significantly increased in the vegan group. Intake of meat, fish and poultry; dairy products; eggs; nuts and seeds; and added fats decreased. Decreased weight was most associated with increased intake of legumes (r=-0.38; p<.0001) and decreased intake of total meat, fish, and poultry (r=+0.43; p<.0001). Those consuming a low-fat vegan diet also increased their intake of carbohydrates, fiber, and several micronutrients and decreased fat intake. Reduced fat intake was associated with reduced body weight (r=+0.15; p=0.02) and, after adjustment for changes in BMI and energy intake, with reduced fat mass (r=+0.14; p=0.04). The intervention group's AHEI-2010 increased by 6.0 points on average in contrast to no significant change in the control group (treatment effect +7.2 [95% CI +3.7 to +10.7]; p<0.001). Increase in AHEI-2010 correlated with reduction in body weight (r=0.14; p=0.04), fat mass (r=-0.14; p=0.03), and insulin resistance as measured by HOMA-IR (r=-0.17; p=0.02), after adjustment for changes in energy intake.

CONCLUSIONS

When compared with participants' usual diets, intake of plant foods increased, and consumption of animal foods, nuts and seeds, and added fats decreased on a low-fat vegan diet. Increased legume intake was the best single food group predictor of weight loss. Diet quality as measured by AHEI-2010 improved on the low-fat vegan diet, which was associated with improvements in weight and metabolic outcomes. These data suggest that increasing low-fat plant foods and minimizing high-fat and animal foods is associated with decreased body weight and fat loss, and that a low-fat vegan diet can improve measures of diet quality and metabolic health.

Plant-Based Diet as a Strategy for Weight Control

According to the World Health Organization, obesity has nearly tripled since the 1970s. Obesity and overweight are major risk factors for cardiovascular diseases, diabetes, inflammatory-mediated diseases, and other serious medical conditions. Moreover, recent data suggest that obesity, overweight, diabetes, and cardiovascular diseases are risk factors for COVID-19-related mortality. Different strategies for weight control have been introduced over the last two decades. Unfortunately, these strategies have shown little effect. At the same time, many studies show that plants might be the key to a successful strategy for weight control. Following the PRISMA guidelines for conducting systematic reviews, a search was conducted in PubMed, Web of Science, Scopus, and Embase using the following keywords: obesity, globesity, vegan, plant-based diet, etc. Our results show that vegan diets are associated with improved gut microbiota symbiosis, increased insulin sensitivity, activation of peroxisome proliferator-activated receptors, and over-expression of mitochondrial uncoupling proteins. The key features of this diet are reduced calorie density and reduced cholesterol intake. The combination of these two factors is the essence of the efficiency of this approach to weight control. Our data suggest that plant-based/vegan diets might play a significant role in future strategies for reducing body weight.

The Association of Plant-Based Diet With Cardiovascular Disease and Mortality: A Meta-Analysis and Systematic Review of Prospect Cohort Studies

Background: The association between plant-based diets and cardiovascular disease (CVD) remains poorly characterized. Given that diet represents an important and a modifiable risk factor, this study aimed to assess (1) the relationships between the impact of adherence to plant-based diets on cardiovascular mortality, incident CVD, and stroke; (2) if associations differed by adherence to healthful and less healthful plant-based diets.

Methods and Findings: MEDLINE and EMBASE databases were searched up to May 2021. Studies assessing CVD outcomes with relation to plant-based dietary patterns or according to plant-based dietary indices (PDI) were included. A meta-analysis of hazard ratios (HR) was conducted using DerSimonian and Laird random effects model. Thirteen studies involving 410,085 participants were included. Greater adherence to an overall plant-based dietary pattern was significantly associated with a lower risk of cardiovascular mortality (pooled HR: 0.92, 95% CI: 0.86–0.99 p = 0.0193, I² = 88.5%, N = 124,501) and a lower risk of CVD incidence (pooled HR: 0.90, 95% CI: 0.82–0.98, p = 0.0173, I² = 87.2%, N = 323,854). Among the studies that used PDI, unhealthful plant-based diets were associated with increased risk of cardiovascular mortality (pooled HR: 1.05, 95% CI: 1.01–1.09, p = 0.0123, I² = 0.00%, N = 18,966), but not CVD incidence. Conversely, healthful plant-based diets were associated with decreased CVD incidence (pooled HR: 0.87, 95% CI: 0.80–0.95, p = 0.0011, I² = 57.5%, N = 71,301), but not mortality. Vegetarians also had significantly lower CVD incidence (HR: 0.81, 95% CI: 0.72–0.91, p = 0.0004, I² = 22.2%, N = 16,254), but similar CVD mortality or stroke risk when compared to the meat-eaters.

Conclusion: To date, this comprehensive study examines the effects of a plant-based diet on major clinical endpoints using more holistic PDIs. These findings highlight the favorable role of healthful plant-based foods in reducing cardiovascular mortality and CVD.

Vegan Diet Health Benefits in Metabolic Syndrome

Plant-based diets (PBDs) are increasingly consumed by the Italian population and around the world. In particular, among PBDs, the vegan diet is a food pattern characterized by the exclusion of all animal-origin foods. What drives people to adopt this model are mainly ethical, health and environmental reasons. A vegan diet, if well-balanced and varied, can help in achieving and maintaining an optimal state of health. However, this nutritional approach, if not well-balanced, can cause deficiencies in proteins, ω-3 fatty acids, iron, vitamin D and calcium, zinc, iodine and, above all, vitamin B12. Oral food supplements especially fortified foods are recommended in these cases to restore the nutritional deficiencies. A vegan diet generally reduces the risk of developing chronic non-communicable degenerative diseases, such as metabolic syndrome (MetS) and, in addition, requires fewer natural resources for food production than an omnivorous diet. The aim of this review is to analyze the possible impact of the vegan diet on MetS onset and its treatment.

Vegan dietary pattern for the primary and secondary prevention of cardiovascular diseases

BACKGROUND

Diet plays a major role in the aetiology of cardiovascular disease (CVD) and as a modifiable risk factor is the focus of many prevention strategies. Recently vegan diets have gained popularity and there is a need to synthesise existing clinical trial evidence for their potential in CVD prevention.

OBJECTIVES

To determine the effectiveness of following a vegan dietary pattern for the primary and secondary prevention of CVD.

SEARCH METHODS

We searched the following electronic databases on 4 February 2020: the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase and Web of Science Core Collection. We also searched ClinicalTrials.gov in January 2021. We applied no language restrictions.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs) in healthy adults and adults at high risk of CVD (primary prevention) and those with established CVD (secondary prevention). A vegan dietary pattern excludes meat, fish, eggs, dairy and honey; the intervention could be dietary advice, provision of relevant foods, or both. The comparison group received either no intervention, minimal intervention, or another dietary intervention. Outcomes included clinical events and CVD risk factors. We included only studies with follow-up periods of 12 weeks or more, defined as the intervention period plus post-intervention follow-up.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion, extracted data and assessed risks of bias. We used GRADE to assess the certainty of the evidence. We conducted three main comparisons: 1. Vegan dietary intervention versus no intervention or minimal intervention for primary prevention; 2. Vegan dietary intervention versus another dietary intervention for primary prevention; 3. Vegan dietary intervention versus another dietary intervention for secondary prevention.

MAIN RESULTS

Thirteen RCTs (38 papers, 7 trial registrations) and eight ongoing trials met our inclusion criteria. Most trials contributed to primary prevention: comparisons 1 (four trials, 466 participants randomised) and comparison 2 (eight trials, 409 participants randomised). We included only one secondary prevention trial for comparison 3 (63 participants randomised). None of the trials reported on clinical endpoints. Other primary outcomes included lipid levels and blood pressure. For comparison 1 there was moderate-certainty evidence from four trials with 449 participants that a vegan diet probably led to a small reduction in total cholesterol (mean difference (MD) -0.24 mmol/L, 95% confidence interval (CI) -0.36 to -0.12) and low-density lipoprotein (LDL) cholesterol (MD -0.22 mmol/L, 95% CI -0.32 to -0.11), a very small decrease in high-density lipoprotein (HDL) levels (MD -0.08 mmol/L, 95% CI -0.11 to -0.04) and a very small increase in triglyceride levels (MD 0.11 mmol/L, 95% CI 0.01 to 0.21). The very small changes in HDL and triglyceride levels are in the opposite direction to that expected. There was a lack of evidence for an effect with the vegan dietary intervention on systolic blood pressure (MD 0.94 mmHg, 95% CI -1.18 to 3.06; 3 trials, 374 participants) and diastolic blood pressure (MD -0.27 mmHg, 95% CI -1.67 to 1.12; 3 trials, 372 participants) (low-certainty evidence). For comparison 2 there was a lack of evidence for an effect of the vegan dietary intervention on total cholesterol levels (MD -0.04 mmol/L, 95% CI -0.28 to 0.20; 4 trials, 163 participants; low-certainty evidence). There was probably little or no effect of the vegan dietary intervention on LDL (MD -0.05 mmol/L, 95% CI -0.21 to 0.11; 4 trials, 244 participants) or HDL cholesterol levels (MD -0.01 mmol/L, 95% CI -0.08 to 0.05; 5 trials, 256 participants) or triglycerides (MD 0.21 mmol/L, 95% CI -0.07 to 0.49; 5 trials, 256 participants) compared to other dietary interventions (moderate-certainty evidence). We are very uncertain about any effect of the vegan dietary intervention on systolic blood pressure (MD 0.02 mmHg, 95% CI -3.59 to 3.62)  or diastolic blood pressure (MD 0.63 mmHg, 95% CI -1.54 to 2.80; 5 trials, 247 participants (very low-certainty evidence)). Only one trial (63 participants) contributed to comparison 3, where there was a lack of evidence for an effect of the vegan dietary intervention on lipid levels or blood pressure compared to other dietary interventions (low- or very low-certainty evidence). Four trials reported on adverse events, which were absent or minor.

AUTHORS' CONCLUSIONS

Studies were generally small with few participants contributing to each comparison group. None of the included studies report on CVD clinical events. There is currently insufficient information to draw conclusions about the effects of vegan dietary interventions on CVD risk factors. The eight ongoing studies identified will add to the evidence base, with all eight reporting on primary prevention. There is a paucity of evidence for secondary prevention.

Spiritually motivated restrictions on animal products have a limited impact on consumption of healthy plant-based foods

Plant-based diets are considered healthier than many omnivorous diets. However, it is unclear that restriction of animal products necessarily motivates increased consumption of nutrient- and fibre-rich plant-based foods as opposed to energy-dense but nutrient-poor plant-based foods containing refined grains and added sugars and fats. The present study examined FFQ and food record data from ninety-nine individuals in the USA with varying degrees of adherence to the Orthodox Christian tradition of restricting meat, dairy and egg (MDE) products for 48 d prior to Easter to investigate whether restricting MDE products in the absence of explicit nutritional guidance would lead to increased consumption of healthy plant-based foods and greater likelihood of meeting dietary recommendations. Multiple linear regression models assessed changes in major food groups, energy and nutrients in relation to the degree of reduction in MDE consumption. Logistic regression analyses tested the odds of meeting 2015-2020 Dietary Guidelines for Americans on plant-based foods in relation to MDE restriction. Each serving reduction in MDE products was associated with small (approximately 0·1-0·7 serving) increases in legumes, soya products and nuts/seeds (all P values < 0·005). MDE restriction was not associated with higher odds of meeting recommendations on vegetable, fruit or whole-grain intake. Consumption of refined grains and added sugars did not change in relation to MDE restriction but remained above recommended thresholds, on average. These findings demonstrate that a reduction of MDE products for spiritual purposes may result in increases in some nutrient-rich plant-based foods but may not uniformly lead to a healthier dietary composition.

Position paper on vegetarian diets from the working group of the Italian Society of Human Nutrition

BACKGROUND

Interest in vegetarian diets is growing in Italy and elsewhere, as government agencies and health/nutrition organizations are emphasizing that regular consumption of plant foods may provide health benefits and help prevent certain diseases.

METHODS AND RESULTS

We conducted a Pubmed search, up to September, 2015, for studies on key nutrients (proteins, vitamin B12, iron, zinc, calcium, vitamin D, and n-3 fatty acids) in vegetarian diets. From 295 eligible publications the following emerged: Vegetarians should be encouraged to supplement their diets with a reliable source of vitamin B12 (vitamin-fortified foods or supplements). Since the plant protein digestibility is lower than that of animal proteins it may be appropriate for vegetarians to consume more proteins than recommended for the general population. Vegetarians should also be encouraged to habitually consume good sources of calcium, iron and zinc - particularly vegetables that are low in oxalate and phytate (e.g. Brassicaceae), nuts and seeds, and calcium-rich mineral water. Calcium, iron, and zinc bioavailability can be improved by soaking, germination, and sour-dough leavening that lower the phytate content of pulses and cereals. Vegetarians can ensure good n-3 fatty acid status by habitually consuming good sources of a-linolenic acid (walnuts, flaxseeds, chia seeds, and their oils) and limiting linoleic acid intake (corn and sunflower oils).

CONCLUSIONS

Well-planned vegetarian diets that include a wide variety of plant foods, and a reliable source of vitamin B12, provide adequate nutrient intake. Government agencies and health/nutrition organizations should provide more educational resources to help Italians consume nutritionally adequate vegetarian diets.

Randomization to plant-based dietary approaches leads to larger short-term improvements in Dietary Inflammatory Index scores and macronutrient intake compared with diets that contain meat

Studies have examined nutrient differences among people following different plant-based diets. However, all of these studies have been observational. The aim of the present study was to examine differences in nutrient intake and Dietary Inflammatory Index (DII) scores among overweight and obese (body mass index 25.0-49.9 kg/m(2)) adults randomized to receive dietary instruction on a vegan (n = 12), vegetarian (n = 13), pescovegetarian (n = 13), semivegetarian (n = 13), or omnivorous (n = 12) diet during a 6-month randomized controlled trial. Nutrient intake, nutrient adequacy, and DII score were assessed via two 24-hour dietary recalls (Automated Self-Administered 24-Hour Dietary Recall) at baseline and at 2 and 6 months. Differences in nutrient intake and the DII were examined using general linear models with follow-up tests at each time point. We hypothesized that individuals randomized to the vegan diet would have lower DII scores and greater improvements in fiber, carbohydrate, fat, saturated fat, and cholesterol at both 2 and 6 months as compared with the other 4 diets. Participants randomized to the vegan diet had significantly greater changes in most macronutrients at both time points, including fat and saturated fat, as well as cholesterol and, at 2 months, fiber, as compared with most of the other diet groups (Ps < .05). Vegan, vegetarian, and pescovegetarian participants all saw significant improvements in the DII score as compared with semivegetarian participants at 2 months (Ps < .05) with no differences at 6 months. Given the greater impact on macronutrients and the DII during the short term, finding ways to provide support for adoption and maintenance of plant-based dietary approaches, such as vegan and vegetarian diets, should be given consideration.

Comparative effectiveness of plant-based diets for weight loss: a randomized controlled trial of five different diets

OBJECTIVE

The aim of this study was to determine the effect of plant-based diets on weight loss.

METHODS

Participants were enrolled in a 6-mo, five-arm, randomized controlled trial in 2013 in South Carolina. Participants attended weekly group meetings, with the exception of the omnivorous group, which served as the control and attended monthly meetings augmented with weekly e-mail lessons. All groups attended monthly meetings for the last 4 mo of the study. Diets did not emphasize caloric restriction.

RESULTS

Overweight adults (body mass index 25-49.9 kg/m(2); age 18-65 y, 19% non-white, and 27% men) were randomized to a low-fat, low-glycemic index diet: vegan (n = 12), vegetarian (n = 13), pesco-vegetarian (n = 13), semi-vegetarian (n = 13), or omnivorous (n = 12). Fifty (79%) participants completed the study. In intention-to-treat analysis, the linear trend for weight loss across the five groups was significant at both 2 (P < 0.01) and 6 mo (P < 0.01). At 6 mo, the weight loss in the vegan group (-7.5% ± 4.5%) was significantly different from the omnivorous (-3.1% ± 3.6%; P = 0.03), semi-vegetarian (-3.2% ± 3.8%; P = 0.03), and pesco-vegetarian (-3.2% ± 3.4%; P = 0.03) groups. Vegan participants decreased their fat and saturated fat more than the pesco-vegetarian, semi-vegetarian, and omnivorous groups at both 2 and 6 mo (P < 0.05).

CONCLUSIONS

Vegan diets may result in greater weight loss than more modest recommendations.

Key elements of plant-based diets associated with reduced risk of metabolic syndrome

Approximately 20 %-25 % of adults worldwide have metabolic syndrome. Vegetarian and vegan diets have demonstrated effectiveness in improving body weight, glycemic control, and cardiovascular risk factors, as compared with conventional therapeutic approaches, and are potentially useful in the prevention of metabolic syndrome. This article consists of two steps: (1) a review of the literature on studies examining vegetarian and vegan diets and metabolic syndrome and (2) a review of foods and nutrients that are protective against or associated with metabolic syndromes that may help to explain the beneficial effects of plant-based dietary approaches for metabolic syndrome. The present review found eight observational research studies, and no intervention studies, examining the association of plant-based dietary approaches with metabolic syndrome. These studies, conducted mostly in Asian populations, yielded varying results. The majority, however, found better metabolic risk factors and lowered risk of metabolic syndrome among individuals following plant-based diets, as compared with omnivores. Some dietary components that are lower in the diets of vegetarians, such as energy intake, saturated fat, heme iron, and red and processed meat, may influence metabolic syndrome risk. In addition, plant-based diets are higher in fruits, vegetables, and fiber, which are protective against the development of metabolic syndrome.

Nutrient intake in the GEICO multicenter trial: the effects of a multicomponent worksite intervention

BACKGROUND/OBJECTIVES

To assess the effects on macro- and micronutrient intake of a nutrition intervention program in corporate settings across the United States.

SUBJECTS/METHODS

Two hundred and ninety-two individuals who were overweight or had type 2 diabetes were recruited from 10 sites of a US insurance company. Two hundred and seventy-one participants completed baseline diet recalls, and 183 participants completed dietary recalls at 18 weeks. Sites were randomly assigned to an intervention group (five sites) or to a control group (five sites) for 18 weeks. At intervention sites, participants were asked to follow a low-fat vegan diet and attend weekly group meetings. At control sites, participants continued their usual diets. At baseline and 18 weeks, participants completed 2-day diet recalls. Between-group differences in changes in nutrient intake were assessed using an analysis of covariance.

RESULTS

Compared with those in the control group, intervention-group participants significantly reduced the reported intake of total fat (P=0.02), saturated (P=0.006) and monounsaturated fats (P=0.01), cholesterol (P=0.009), protein (P=0.03) and calcium (P=0.02), and increased the intake of carbohydrate (P=0.006), fiber (P=0.002), β-carotene (P=0.01), vitamin C (P=0.003), magnesium (P=0.04) and potassium (P=0.002).

CONCLUSIONS

An 18-week intervention program in a corporate setting reduces intake of total fat, saturated fat and cholesterol and increases the intake of protective nutrients, particularly fiber, β-carotene, vitamin C, magnesium and potassium. The reduction in calcium intake indicates the need for planning for this nutrient.

Effect of vegetarian diets on zinc status: a systematic review and meta-analysis of studies in humans

Plant-based diets contain less saturated fat and cholesterol and more folate, fibre and phytochemicals than omnivorous diets, but some micronutrients, especially zinc, are poorly bioavailable. The findings of studies exploring the zinc intake and zinc status in populations that habitually consume vegetarian diets are inconsistent. This study aims to investigate the effects of plant-based diets on dietary zinc intake and status in humans using systematic review and meta-analysis techniques. Thirty-four studies were included in the systematic review. Of these, 26 studies (reporting 48 comparisons) compared males and/or females consuming vegetarian diets with non-vegetarian groups and were included in meta-analyses. Dietary zinc intakes and serum zinc concentrations were significantly lower (-0.88 ± 0.15 mg day(-1), P < 0.001 and -0.93 ± 0.27 µmol L(-1), P = 0.001 respectively; mean ± standard error) in populations that followed habitual vegetarian diets compared with non-vegetarians. Secondary analyses showed greater impact of vegetarian diets on the zinc intake and status of females, vegetarians from developing countries and vegans. Populations that habitually consume vegetarian diets have low zinc intakes and status. Not all vegetarian categories impact zinc status to the same extent, but a lack of consistency in defining vegetarian diets for research purposes makes dietary assessment difficult. Dietary practices that increase zinc bioavailability, the consumption of foods fortified with zinc or low-dose supplementation are strategies that should be considered for improving the zinc status of vegetarians with low zinc intakes or serum zinc concentrations at the lower end of the reference range.

A vegetarian dietary pattern as a nutrient-dense approach to weight management: an analysis of the national health and nutrition examination survey 1999-2004

BACKGROUND

Population-based studies have shown that vegetarians have lower body mass index than nonvegetarians, suggesting that vegetarian diet plans may be an approach for weight management. However, a perception exists that vegetarian diets are deficient in certain nutrients.

OBJECTIVE

To compare dietary quality of vegetarians, nonvegetarians, and dieters, and to test the hypothesis that a vegetarian diet would not compromise nutrient intake when used to manage body weight.

DESIGN

Cross-sectional analysis of National Health and Nutrition Examination Survey (1999-2004) dietary and anthropometric data. Diet quality was determined using United States Department of Agriculture's Healthy Eating Index 2005. Participants included adults aged 19 years and older, excluding pregnant and lactating women (N = 13,292). Lacto-ovo vegetarian diets were portrayed by intakes of participants who did not eat meat, poultry, or fish on the day of the survey (n = 851). Weight-loss diets were portrayed by intakes of participants who consumed 500 kcal less than their estimated energy requirements (n = 4,635). Mean nutrient intakes and body mass indexes were adjusted for energy, sex, and ethnicity. Using analysis of variance, all vegetarians were compared to all nonvegetarians, dieting vegetarians to dieting nonvegetarians, and nondieting vegetarians to nondieting nonvegetarians.

RESULTS

Mean intakes of fiber, vitamins A, C, and E, thiamin, riboflavin, folate, calcium, magnesium, and iron were higher for all vegetarians than for all nonvegetarians. Although vegetarian intakes of vitamin E, vitamin A, and magnesium exceeded that of nonvegetarians (8.3 ± 0.3 vs 7.0 ± 0.1 mg; 718 ± 28 vs 603 ± 10 μg; 322 ± 5 vs 281 ± 2 mg), both groups had intakes that were less than desired. The Healthy Eating Index score did not differ for all vegetarians compared to all nonvegetarians (50.5 ± 0.88 vs 50.1 ± 0.33, P = 0.6).

CONCLUSIONS

These findings suggest that vegetarian diets are nutrient dense, consistent with dietary guidelines, and could be recommended for weight management without compromising diet quality.

Usefulness of vegetarian and vegan diets for treating type 2 diabetes

Significant benefits for diabetes prevention and management have been observed with vegetarian and especially vegan diets. This article reviews observational studies and intervention trials on such diets, and discusses their efficacy, nutritional adequacy, acceptability, and sustainability. Research to date has demonstrated that a low-fat, plant-based nutritional approach improves control of weight, glycemia, and cardiovascular risk. These studies have also shown that carefully planned vegan diets can be more nutritious than diets based on more conventional diet guidelines, with an acceptability that is comparable with that of other therapeutic regimens. Current intervention guidelines from professional organizations offer support for this approach. Vegetarian and vegan diets present potential advantages in managing type 2 diabetes that merit the attention of individuals with diabetes and their caregivers.

The association between high plasma homocysteine levels and lower bone mineral density in Slovak women: the impact of vegetarian diet

BACKGROUND

A long-term vegetarian diet is generally poor in vitamin B group. The lack of vitamin B(12) together with vitamin B(6) and folate deficiency is closely related to homocysteine metabolism. Hyperhomocysteinemia was found to be associated with increased bone turnover markers and increased fracture risk. Thus, hyperhomocysteinemia, vitamin B(12) and folate deficiency may be regarded as novel risk factors for micronutrient deficiency-related osteoporosis.

AIM OF THE STUDY

To assess the possible impact of a vegetarian diet on bone mineral density in cohort of Slovak vegetarian women.

METHODS

Fasting serum glucose, albumin, calcium, phosphorous and creatinine as well as bone markers, serum vitamin B(12), folate and plasma levels of total homocysteine were assessed in two nutritional groups (vegetarians vs. nonvegetarians) of apparently healthy women (age range 20-70 years). Bone mineral density of the femoral neck, trochanter, total femur and lumbar spine was measured in all subjects.

RESULTS

Vegetarians had a significantly lower weight (p < 0.05), higher PTH (p < 0.01) and homocysteine (p < 0.001). Vitamin B(12) was significantly higher in nonvegetarians (p < 0.001). No differences were observed in folate levels. Univariate analysis showed significant association between homocysteine and B(12) (p < 0.01), folate (p < 0.001), creatinine (p < 0.001), total proteins (p < 0.049), age (p < 0.001) and vegetarian food intake (p < 0.001). Vegetarians had a significantly lower TrFBMD (p < 0.05) and ToFBMD (p < 0.05). Age and CTx were significant predictors in all sites of measured BMD and PTH. A strong correlation between homocysteine and FNBMD (r = -0.2009, p < 0.002), TrFBMD (r = -0.1810, p < 0.004) and ToFBMD (r = -0.2225, p < 0.001) was found in all subjects.

CONCLUSION

Homocysteine is one of the predictors of bone mineral density, and hyperhomocysteinemia is associated with lower bone mineral density. In healthy adults, homocysteine levels are dependent on age as well as on nutritional habits. Thus, elderly women on a vegetarian diet seem to be at higher risk of osteoporosis development than nonvegetarian women.

Vegetarian and vegan diets in type 2 diabetes management

Vegetarian and vegan diets offer significant benefits for diabetes management. In observational studies, individuals following vegetarian diets are about half as likely to develop diabetes, compared with non-vegetarians. In clinical trials in individuals with type 2 diabetes, low-fat vegan diets improve glycemic control to a greater extent than conventional diabetes diets. Although this effect is primarily attributable to greater weight loss, evidence also suggests that reduced intake of saturated fats and high-glycemic-index foods, increased intake of dietary fiber and vegetable protein, reduced intramyocellular lipid concentrations, and decreased iron stores mediate the influence of plant-based diets on glycemia. Vegetarian and vegan diets also improve plasma lipid concentrations and have been shown to reverse atherosclerosis progression. In clinical studies, the reported acceptability of vegetarian and vegan diets is comparable to other therapeutic regimens. The presently available literature indicates that vegetarian and vegan diets present potential advantages for the management of type 2 diabetes.

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.

A dietary intervention to elicit rapid and complex dietary changes for studies investigating the effects of diet on tissues collected during invasive surgical procedures

Nutrition intervention trials in patients undergoing surgical treatment for cancer offer a unique opportunity to study the mechanisms and pathways that underlie diet and cancer associations in target tissues. However, due to the short time period between diagnosis and treatment, traditional dietary intervention methods are not feasible. This report describes a novel dietary intervention program designed to elicit rapid and complex dietary change during a condensed study period. The intervention, based on Consumer Information Processing, used standardized menus and exchange lists to guide food choices, and was delivered using a single, in-person session followed by telephone-based counseling. This intervention program was used in a small pilot study evaluating the short-term effects of dietary change in men with newly diagnosed prostate cancer. Eight men were randomly assigned to either a low-fat/low-glycemic load or standard American diet during the 4 weeks preceding prostate surgery. Participants completed 24-hour dietary recalls each week, and were weighed at baseline and at surgery. Compared to men in the standard American arm (n=4), men in the low-fat/low-glycemic arm (n=4) reported consuming less total fat (51.0+/-36.0 vs 93.5+/-8.4 g/day, P=0.06), and had a lower glycemic load (134.8+/-6.0 vs 266.3+/-36.8 units/day, P<0.001). Men in the low-fat/low-glycemic arm lost a mean of 5.3+/-1.7 kg and men in the standard American arm gained 0.8+/-4.5 kg (P=0.04). Results of this small pilot study suggest that a relatively simple and minimally burdensome dietary intervention can elicit rapid and complex dietary changes that are maintained over a 4-week study period. Further studies in larger and more diverse populations are needed to fully understand the potential of this novel intervention approach.

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.

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.

Vegetarian Diets and Weight Status

The increasing global health problems of overweight and obesity are associated with coronary heart disease, hypertension, diabetes, osteoarthritis, and certain cancers, among other health concerns. Vegetarian diets are associated with reduced body weight, lower incidence of certain chronic disease, and lower medical costs compared with non-vegetarian diets. We reviewed the literature to ascertain the extent to which and by what mechanism(s) a plant-based diet may mediate body weight.

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.

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.