Plasma lipids and lipoprotein cholesterol concentrations in people with different diets in Britain

Vegetarian and vegan diets and the risk of cardiovascular disease, ischemic heart disease and stroke: a systematic review and meta-analysis of prospective cohort studies

PURPOSE

Vegetarian diets have been associated with reduced risk of ischemic heart disease (IHD). However, results regarding cardiovascular disease (CVD) overall and stroke are less clear. We conducted a systematic review and meta-analysis of prospective cohort studies on CVD, IHD and stroke risk among vegetarians or vegans versus nonvegetarians to clarify these associations.

METHODS

PubMed and Ovid Embase databases were searched through August 12, 2021. Prospective cohort studies reporting adjusted relative risk (RR) estimates and 95% confidence intervals (CIs) for incidence or mortality from CVD, IHD and stroke, comparing vegetarians and vegans to nonvegetarians were included. Risk of bias (RoB) was assessed using ROBINS-I and the strength of evidence was assessed using World Cancer Research Fund (WCRF) criteria. Summary RRs (95% CIs) were estimated using a random effects model.

RESULTS

Thirteen cohort studies (844,175 participants, 115,392 CVD, 30,377 IHD, and 14,419 stroke cases) were included. The summary RR for vegetarians vs. nonvegetarians was 0.85 (95% CI: 0.79-0.92, I² = 68%, n = 8) for CVD, 0.79 (95% CI: 0.71-0.88, I² = 67%, n = 8) for IHD, 0.90 (95% CI: 0.77-1.05, I² = 61%, n = 12) for total stroke, and for vegans vs. nonvegetarians was 0.82 (95% CI: 0.68-1.00, I² = 0%, n = 6) for IHD. RoB was moderate (n = 8) to serious (n = 5). The associations between vegetarian diets and CVD and IHD were considered probably causal using WCRF criteria.

CONCLUSIONS

Vegetarian diets are associated with reduced risk of CVD and IHD, but not stroke, but further studies are needed on stroke. These findings should be considered in dietary guidelines.

REVIEW REGISTRATION

No review protocol registered.

α-linolenic acid interconversion is sufficient as a source of longer chain ω-3 polyunsaturated fatty acids in humans: An opinion

α-linolenic acid (αLNA) conversion into the functionally important ω-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), has been regarded as inadequate for meeting nutritional requirements for these PUFA. This view is based on findings of small αLNA supplementation trials and stable isotope tracer studies that have been interpreted as indicating human capacity for EPA and, in particular, DHA synthesis is limited. The purpose of this review is to re-evaluate this interpretation. Markedly differing study designs, inconsistent findings and lack of trial replication preclude robust consensus regarding the nutritional adequacy of αLNA as a source of EPC and DHA. The conclusion that αLNA conversion in humans is constrained is inaccurate because it presupposes the existence of an unspecified, higher level of metabolic activity. Since capacity for EPA and DHA synthesis is the product of evolution it may be argued that the levels of EPA and DHA it maintains are nutritionally appropriate. Dietary and supra-dietary EPA plus DHA intakes confer health benefits. Paradoxically, such health benefits are also found amongst vegetarians who do not consume EPA and DHA, and for whom αLNA conversion is the primary source of ω-3 PUFA. Since there are no reported adverse effects on health or cognitive development of diets that exclude EPA and DHA, their synthesis from αLNA appears to be nutritionally adequate. This is consistent with the dietary essentiality of αLNA and has implications for developing sustainable nutritional recommendations for ω-3 PUFA.

Biomarker Concentrations in White and British Indian Vegetarians and Nonvegetarians in the UK Biobank

BACKGROUND

Prospective studies have shown differences in some disease risks between vegetarians and nonvegetarians, but the potential biological pathways are not well understood.

OBJECTIVES

We aimed to assess differences in concentrations of biomarkers related to disease pathways in people with varying degrees of animal foods exclusion.

METHODS

The UK Biobank recruited 500,000 participants aged 40-69 y (54.4% women) throughout the United Kingdom in 2006-2010. Blood and urine were collected at recruitment and assayed for more than 30 biomarkers related to cardiovascular diseases, bone and joint health, cancer, diabetes, renal disease, and liver health. In cross-sectional analyses, we estimated adjusted geometric means of these biomarkers by 6 diet groups (regular meat eaters, low meat eaters, poultry eaters, fish eaters, vegetarians, vegans) in 466,058 white British participants and 2 diet groups (meat eaters, vegetarians) in 5535 British Indian participants.

RESULTS

We observed differences in the concentrations of most biomarkers, with many biomarkers showing a gradient effect from meat eaters to vegetarians/vegans. Of the largest differences, compared with white British regular meat eaters, white British vegans had lower C-reactive protein [adjusted geometric mean (95% CI): 1.13 (1.03, 1.25) compared with 1.43 (1.42, 1.43) mg/L], lower low-density lipoprotein cholesterol [3.13 (3.07, 3.20) compared with 3.65 (3.65, 3.65) mmol/L], lower vitamin D [34.4 (33.1, 35.9) compared with 44.5 (44.4, 44.5) nmol/L], lower serum urea [4.21 (4.11, 4.30) compared with 5.36 (5.36, 5.37) mmol/L], lower urinary creatinine [5440 (5120, 5770) compared with 7280 (7260, 7300) μmol/L], and lower γ-glutamyltransferase [23.5 (22.2, 24.8) compared with 29.6 (29.6, 29.7) U/L]. Patterns were mostly similar in British Indians, and results were consistent between women and men.

CONCLUSIONS

The observed differences in biomarker concentrations, including lower C-reactive protein, lower LDL cholesterol, lower vitamin D, lower creatinine, and lower γ-glutamyltransferase, in vegetarians and vegans may relate to differences in future disease risk.

Intake and adequacy of the vegan diet. A systematic review of the evidence

BACKGROUND

Vegan diets, where animal- and all their by-products are excluded from the diet, have gained popularity, especially in the last decade. However, the evaluation of this type of diet has not been well addressed in the scientific literature. This study aimed to investigate the adequacy of vegan diets in European populations and of their macro- and micronutrient intakes compared to World Health Organization recommendations.

METHODS

A systematic search in PubMed, Web of Science, IBSS, Cochrane library and Google Scholar was conducted and 48 studies (12 cohorts and 36 cross-sectional) were included.

RESULTS

Regarding macronutrients, vegan diets are lower in protein intake compared with all other diet types. Veganism is also associated with low intake of vitamins B₂, Niacin (B₃), B₁₂, D, iodine, zinc, calcium, potassium, selenium. Vitamin B₁₂ intake among vegans is significantly lower (0.24-0.49 μg, recommendations are 2.4 μg) and calcium intake in the majority of vegans was below recommendations (750 mg/d). No significant differences in fat intake were observed. Vegan diets are not related to deficiencies in vitamins A, B₁, Β₆, C, E, iron, phosphorus, magnesium, copper and folate and have a low glycemic load.

CONCLUSIONS

Following a vegan diet may result in deficiencies in micronutrients (vitamin B₁₂, zinc, calcium and selenium) which should not be disregarded. However, low micro- and macronutrient intakes are not always associated with health impairments. Individuals who consume a vegan diet should be aware of the risk of potential dietary deficiencies.

Vegetable but not animal protein intake is associated to a better physical performance: a study on a general population sample of adults

Background

The research was conducted in the frame of a population-based, case control study, called Genes Environment Interaction in Respiratory Disease.

Objective

To assess the association between protein intake and physical performance in a general population sample.

Design

Researchers investigated the association between the participants’ dietary information and their physical performance using the 6-min walking test and the distance walked in metres (6MWD) as main outcome measure. Information on dietary intake was collected using the validated European Investigation into Cancer and Nutrition food frequency questionnaires (FFQs). Then, daily intake of energy and macronutrients was estimated by means of the NAF software (nutritional analysis of FFQ). Linear regression models were used to evaluate the associations between vegetable, animal and total protein intakes and the 6MWD. The models were adjusted for socio-demographic features, total fats and available carbohydrate intakes.

Results

The participants were 223 subjects (57% females) aged between 23 and 68 years. Their mean vegetable and animal proteins intake for gram/kg of body weight/day were, respectively, 0.4 and 0.7. After adjusting for all the potential confounders, there was a significant increase of 20.0 (95% CI 0.8; 39.2) m in the distance walked for an increase in 10 g/day of vegetable proteins and non-significant variations of −1.8 (95% CI −9.3; 5.7) m for an increase in 10 g/day of animal proteins and of 0.5 (95% CI −6.8; 7.7) for an increase in 10 g/day of total proteins.

Discussion and conclusions

Our result suggests a positive role of vegetable proteins on physical performance. Whether this result is related to the high protein intake itself or may be a consequence of the other properties of plant-based foods deserves further investigation.

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

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

Risks of ischaemic heart disease and stroke in meat eaters, fish eaters, and vegetarians over 18 years of follow-up: results from the prospective EPIC-Oxford study

OBJECTIVE

To examine the associations of vegetarianism with risks of ischaemic heart disease and stroke.

DESIGN

Prospective cohort study.

SETTING

The EPIC-Oxford study, a cohort in the United Kingdom with a large proportion of non-meat eaters, recruited across the country between 1993 and 2001.

PARTICIPANTS

48 188 participants with no history of ischaemic heart disease, stroke, or angina (or cardiovascular disease) were classified into three distinct diet groups: meat eaters (participants who consumed meat, regardless of whether they consumed fish, dairy, or eggs; n=24 428), fish eaters (consumed fish but no meat; n=7506), and vegetarians including vegans (n=16 254), based on dietary information collected at baseline, and subsequently around 2010 (n=28 364).

MAIN OUTCOME MEASURES

Incident cases of ischaemic heart disease and stroke (including ischaemic and haemorrhagic types) identified through record linkage until 2016.

RESULTS

Over 18.1 years of follow-up, 2820 cases of ischaemic heart disease and 1072 cases of total stroke (519 ischaemic stroke and 300 haemorrhagic stroke) were recorded. After adjusting for sociodemographic and lifestyle confounders, fish eaters and vegetarians had 13% (hazard ratio 0.87, 95% confidence interval 0.77 to 0.99) and 22% (0.78, 0.70 to 0.87) lower rates of ischaemic heart disease than meat eaters, respectively (P<0.001 for heterogeneity). This difference was equivalent to 10 fewer cases of ischaemic heart disease (95% confidence interval 6.7 to 13.1 fewer) in vegetarians than in meat eaters per 1000 population over 10 years. The associations for ischaemic heart disease were partly attenuated after adjustment for self reported high blood cholesterol, high blood pressure, diabetes, and body mass index (hazard ratio 0.90, 95% confidence interval 0.81 to 1.00 in vegetarians with all adjustments). By contrast, vegetarians had 20% higher rates of total stroke (hazard ratio 1.20, 95% confidence interval 1.02 to 1.40) than meat eaters, equivalent to three more cases of total stroke (95% confidence interval 0.8 to 5.4 more) per 1000 population over 10 years, mostly due to a higher rate of haemorrhagic stroke. The associations for stroke did not attenuate after further adjustment of disease risk factors.

CONCLUSIONS

In this prospective cohort in the UK, fish eaters and vegetarians had lower rates of ischaemic heart disease than meat eaters, although vegetarians had higher rates of haemorrhagic and total stroke.

Effect of vegetarian diets on the presentation of metabolic syndrome or its components: A systematic review and meta-analysis

BACKGROUND & AIMS

Several studies have examined the effect of vegetarian diets (VD) on metabolic syndrome (MetS) or its components, but findings have been inconsistent. The aim of this study was to perform a systematic review and meta-analysis of randomized controlled trials (RCTs) and observational studies to assess the association between VD and MetS or its components (systolic blood pressure [SBP], diastolic blood pressure [DBP], fasting glucose triglycerides, waist circumference [WC], HDL-cholesterol (HDL-C)) in adults.

METHODS

The Cochrane Library, EMBASE, PubMed, Web of Science, and Scopus were searched. RCTs, cohort studies and cross-sectional studies evaluating the effects of VD on MetS or its components in adults, with omnivore diet as control group, were included. Random effects meta-analyses stratified by study design were employed to calculate pooled estimates.

RESULTS

A total of 71 studies (n = 103 008) met the inclusion criteria (6 RCTs, 2 cohorts, 63 cross-sectional). VD were not associated with MetS in comparison to omnivorous diet (OR 0.96, 95% CI 0.50-1.85, p = 0.9) according to meta-analysis of five cross-sectional studies. Likewise, meta-analysis of RCTs and cohort studies indicated that consumption of VD were not associated with MetS components. Meta-analysis of cross-sectional studies demonstrated that VD were significantly associated with lower levels of SBP (mean difference [MD] -4.18 mmHg, 95%CI -5.57 to -2.80, p < 0.00001), DBP (MD -3.03 mmHg, 95% CI -4.93 to -1.13, p = 0.002), fasting glucose (MD -0.26 mmol/L, 95% CI -0.35to -0.17, p < 0.00001), WC (MD -1.63 cm, 95% CI -3.13 to -0.13, p = 0.03), and HDL-C (MD -0.05 mmol/L, 95% CI -0.07 to -0.03, p < 0.0001) in comparison to omnivorous diet. Heterogeneity of effects among cross-sectional studies was high. About, one-half of the included studies had high risk of bias.

CONCLUSIONS

VD in comparison with omnivorous diet is not associated with a lower risk of MetS based on results of meta-analysis of cross-sectional studies. The association between VD and lower levels of SBP, DBP, HDL-C, and fasting glucose is uncertain due to high heterogeneity across the cross-sectional studies. Larger and controlled studies are needed to evaluate the association between VD and MetS and its components.

Vegetarian Dietary Patterns and Cardiovascular Disease

Cardiovascular (CV) disease (CVD) is the leading global cause of mortality, being responsible for 46% of non-communicable disease deaths. It has been estimated that about 85.6 million Americans are living with some form of CVD, which continues to rise. Healthy lifestyle choices may reduce the risk of myocardial infarction by >80%, with nutrition playing a key role. Vegetarian dietary patterns reduce CVD mortality and the risk of coronary heart disease (CHD) by 40%. Plant-based diets are the only dietary pattern to have shown reversal of CHD. Additionally, evidence suggests benefits of vegetarian dietary patterns in both the prevention and the treatment of heart failure and cerebrovascular disease. Plant-based diets are associated with lower blood pressure, lower blood lipids, and reduced platelet aggregation than non-vegetarian diets and are beneficial in weight management, reduce the risk of developing metabolic syndrome, and type 2 diabetes. They have also been shown an effective treatment method in diabetes management. Well planned vegetarian diets provide benefits in preventing and reversing atherosclerosis and in decreasing CVD risk factors and should be promoted through dietary guidelines and recommendations.

Asymptomatic Hypothyroidism and Hypercholesterolemia

Hypothyroidism is a cause of secondary hyperlipidaemia. This study investigates the frequency of biochemically diagnosed hypothyroidism and its relationship with plasma cholesterol concentration in apparently healthy people.

Thyroid function tests (total T4, TSH, and free T4) were performed on 272 apparently healthy men and women (179 vegetarians, 93 meat eaters) with a plasma cholesterol concentration above 7 mmol/l and on 90 individuals with a plasma cholesterol below 4.1 mmol/l who were matched for age, sex and dietary habits.

Six per cent of those with a plasma cholesterol above 7 mmol/l had biochemical evidence of hypothyroidism as defined by a TSH greater than 10 mIU/l (reference range 1–6) and a low free T4 below 10 pmol/l (reference range 10.1–25). Eighty per cent of these people had a high titre of thyroid anti-microsomal antibodies. Of the 90 individuals with a plasma cholesterol level below 4.1 and the 25 randomly selected participants none had biochemical evidence of hypothyroidism.

Hypothyroidism is relatively common in apparently healthy people with a raised plasma cholesterol. It appears no commoner in vegetarians than in meat eaters.

Prevalence, patterns, and associations of dyslipidemia among Sri Lankan adults-Sri Lanka Diabetes and Cardiovascular Study in 2005-2006

BACKGROUND

Dyslipidemia is a major risk factor for cardiovascular disease. Prevalence patterns and determinants of dyslipidemia in Sri Lanka are unkown.

OBJECTIVES

We aimed to determine the prevalence and correlates of dyslipidemia among Sri Lankan adults.

METHODS

A nationally representative sample was recruited by multistage random cluster sampling in Sri Lanka Diabetes and Cardiovascular Study, a cross-sectional study. Data collected by an interviewer-administered questionnaire, physical examination, anthropometric measurements lipid analysis from take 12-hour fasting blood samples were used.

RESULTS

Among 4451 participants 60.5% were women and mean age was 46 years. Mean (standard deviation) total cholesterol (TC), high-density lipoprotein cholesterol (HDLC), low-density lipoprotein cholesterol (LDLC), triglycerides (TGs), and TC/HDLC levels were 206.7 mg/dL (±43.5), 46.8 mg/dL (±10.6), 135.5 mg/dL (±37.6), 121.7 mg/dL (±66.8), and 4.6 (±1.1), respectively. Women had higher mean TC, HDLC, LDLC, and TG values compared to men across all age groups. Mean TC, LDLC, and TGs increased with age in both genders; 77.4% of participants had some form of dyslipidemia. Low HDLC was the commonest type (49.6%) of dyslipidemia. Increasing age, female sex, living in urban sector, high body mass index, central obesity, diabetes, hypertension, insufficient physical activity, and smoking were associated with having some form of dyslipidemia.

CONCLUSION

Three in four Sri Lankan adults have some form of dyslipidemia. Physical inactivity, obesity, hypertension, and diabetes are the leading modifiable risk factors.

A comparison of heart rate variability, n-3 PUFA status and lipid mediator profile in age- and BMI-matched middle-aged vegans and omnivores

Low heart rate variability (HRV) predicts sudden cardiac death. Long-chain (LC) n-3 PUFA (C20-C22) status is positively associated with HRV. This cross-sectional study investigated whether vegans aged 40-70 years (n 23), whose diets are naturally free from EPA (20 : 5n-3) and DHA (22 : 6n-3), have lower HRV compared with omnivores (n 24). Proportions of LC n-3 PUFA in erythrocyte membranes, plasma fatty acids and concentrations of plasma LC n-3 PUFA-derived lipid mediators were significantly lower in vegans. Day-time interbeat intervals (IBI), adjusted for physical activity, age, BMI and sex, were significantly shorter in vegans compared with omnivores (mean difference -67 ms; 95 % CI -130, -3·4, P50 % and high-frequency power) were similarly lower in vegans, with no differences during sleep. In conclusion, vegans have higher 24 h SDNN, but lower day-time HRV and shorter day-time IBI relative to comparable omnivores. Vegans may have reduced availability of precursor markers for pro-resolving lipid mediators; it remains to be determined whether there is a direct link with impaired cardiac function in populations with low-n-3 status.

The long-term health of vegetarians and vegans

Vegetarians, who do not eat any meat, poultry or fish, constitute a significant minority of the world's population. Lacto-ovo-vegetarians consume dairy products and/or eggs, whereas vegans do not eat any foods derived wholly or partly from animals. Concerns over the health, environmental and economic consequences of a diet rich in meat and other animal products have focussed attention on those who exclude some or all of these foods from their diet. There has been extensive research into the nutritional adequacy of vegetarian diets, but less is known about the long-term health of vegetarians and vegans. We summarise the main findings from large cross-sectional and prospective cohort studies in western countries with a high proportion of vegetarian participants. Vegetarians have a lower prevalence of overweight and obesity and a lower risk of IHD compared with non-vegetarians from a similar background, whereas the data are equivocal for stroke. For cancer, there is some evidence that the risk for all cancer sites combined is slightly lower in vegetarians than in non-vegetarians, but findings for individual cancer sites are inconclusive. Vegetarians have also been found to have lower risks for diabetes, diverticular disease and eye cataract. Overall mortality is similar for vegetarians and comparable non-vegetarians, but vegetarian groups compare favourably with the general population. The long-term health of vegetarians appears to be generally good, and for some diseases and medical conditions it may be better than that of comparable omnivores. Much more research is needed, particularly on the long-term health of vegans.

Gut microbiota and Ma-Pi 2 macrobiotic diet in the treatment of type 2 diabetes

In the past 10 years the prevalence of type 2 diabetes mellitus (T2DM) has increased hugely worldwide, driven by a rise in the numbers of overweight and obese individuals. A number of diets have been shown to be effective for the management of T2DM: the Mediterranean diet, the vegetarian diet and the low-calorie diet. Results of studies clearly indicate, however, that the efficacy of these diets is not solely related to the biochemical structure of the individual nutrients they contain. This review discusses this point with reference to the potential role of the intestinal microbiota in diabetes. The macrobiotic Ma-Pi 2 diet is rich in carbohydrates, whole grains and vegetables, with no animal fat or protein or added sugar. In short- and medium-term trials conducted in patients with T2DM, the Ma-Pi 2 diet has been found to significantly improve indicators of metabolic control, including fasting blood glucose, glycosylated hemoglobin, the serum lipid profile, body mass index, body weight and blood pressure. The diet may also alter the gut microbiota composition, which could additionally affect glycemic control. As a result, the Ma-Pi 2 diet could be considered a valid additional short- to medium-term treatment for T2DM.

The association between a vegetarian diet and cardiovascular disease (CVD) risk factors in India: the Indian Migration Study

Background

Studies in the West have shown lower cardiovascular disease (CVD) risk among people taking a vegetarian diet, but these findings may be confounded and only a minority selects these diets. We evaluated the association between vegetarian diets (chosen by 35%) and CVD risk factors across four regions of India.

Methods

Study participants included urban migrants, their rural siblings and urban residents, of the Indian Migration Study from Lucknow, Nagpur, Hyderabad and Bangalore (n = 6555, mean age-40.9 yrs). Information on diet (validated interviewer-administered semi-quantitative food frequency questionnaire), tobacco, alcohol, physical history, medical history, as well as blood pressure, fasting blood and anthropometric measurements were collected. Vegetarians ate no eggs, fish, poultry or meat. Using robust standard error multivariate linear regression models, we investigated the association of vegetarian diets with blood cholesterol, low density lipoprotein (LDL), high density lipoprotein (HDL), triglycerides, fasting blood glucose (FBG), systolic (SBP) and diastolic blood pressure (DBP).

Results

Vegetarians (32.8% of the study population) did not differ from non-vegetarians with respect to age, use of smokeless tobacco, body mass index, and prevalence of diabetes or hypertension. Vegetarians had a higher standard of living and were less likely to smoke, drink alcohol (p<0.0001) and were less physically active (p = 0.04). In multivariate analysis, vegetarians had lower levels of total cholesterol (β = −0.1 mmol/L (95% CI: −0.03 to −0.2), p = 0.006), triglycerides (β = −0.05 mmol/L (95% CI: −0.007 to −0.01), p = 0.02), LDL (β = −0.06 mmol/L (95% CI: −0.005 to −0.1), p = 0.03) and lower DBP (β = −0.7 mmHg (95% CI: −1.2 to −0.07), p = 0.02). Vegetarians also had decreases in SBP (β = −0.9 mmHg (95% CI: −1.9 to 0.08), p = 0.07) and FBG level (β = −0.07 mmol/L (95% CI: −0.2 to 0.01), p = 0.09) when compared to non-vegetarians.

Conclusion

We found beneficial association of vegetarian diet with cardiovascular risk factors compared to non-vegetarian diet.

Comparison of vegetarian diets and omnivorous diets on plasma level of HDL-c: a meta-analysis

Low plasma level of high density lipoprotein cholesterol (HDL-c) was an independent risk factor for cardio vascular disorder, and associated with poor outcomes in pulmonary arterial hypertension. To compare the effects of vegetarian diets and omnivorous diets on HDL-c in plasma, we identified cross-sectional and cohort studies related to HDL-c listed on PubMed and ISI Web of Knowledge as well as the corresponding references (until Nov, 2013). Twelve studies with a total of 4177 individuals were selected for meta-analysis. This meta-analysis indicates that vegetarian diets did not alter plasma HDL-c concentrations, as it wasn’t initially expected by the authors [Standardized Mean Difference (SMD) = 0.02 mmol/l; 95% confidence interval (CI): −0.19 to 0.22 mmol/l]. In Asia and Latin America countries, no significant differences in HDL-c levels between vegetarians and omnivores were found (SMD = −0.09 mmol/l; 95% CI: −0.43 to 0.25 mmol/l). In Europe and North America countries, the plasma level of HDL-c was also not different between the two diets (SMD = 0.09 mmol/l; 95% CI: −0.19 to 0.36 mmol/l). In light of this meta-analysis, we conclude that there is no evidence that plasma HDL-c levels differs in vegetarians and omnivores, even after adjusting for cultural circumstances.

Serum concentrations of cholesterol, apolipoprotein A-I and apolipoprotein B in a total of 1694 meat-eaters, fish-eaters, vegetarians and vegans

BACKGROUND/OBJECTIVES

The objective of this study was to describe serum lipid concentrations, including apolipoproteins A-I and B, in different diet groups.

SUBJECTS/METHODS

A cross-sectional analysis of a sample of 424 meat-eaters, 425 fish-eaters, 423 vegetarians and 422 vegans, matched on sex and age, from the European Prospective Investigation into Cancer and Nutrition-Oxford cohort. Serum concentrations of total, and high-density lipoprotein (HDL) cholesterol, as well as apolipoproteins A-I and B were measured, and serum non-HDL cholesterol was calculated.

RESULTS

Vegans had the lowest body mass index (BMI) and the highest and lowest intakes of polyunsaturated and saturated fat, respectively. After adjustment for age, alcohol and physical activity, compared with meat-eaters, fish-eaters and vegetarians, serum concentrations of total and non-HDL cholesterol and apolipoprotein B were significantly lower in vegans. Serum apolipoprotein A-I concentrations did not differ between the diet groups. In males, the mean serum total cholesterol concentration was 0.87 mmol/l lower in vegans than in meat-eaters; after further adjustment for BMI this difference was 0.76 mmol/l. In females, the difference in total cholesterol between these two groups was 0.6 mmol/l, and after further adjustment for BMI was 0.55 mmol/l. [corrected].

CONCLUSIONS

In this study, which included a large number of vegans, serum total cholesterol and apolipoprotein B concentrations were lower in vegans compared with meat-eaters, fish-eaters and vegetarians. A small proportion of the observed differences in serum lipid concentrations was explained by differences in BMI, but a large proportion is most likely due to diet.

Risk of hospitalization or death from ischemic heart disease among British vegetarians and nonvegetarians: results from the EPIC-Oxford cohort study

BACKGROUND

Few previous prospective studies have examined differences in incident ischemic heart disease (IHD) risk between vegetarians and nonvegetarians.

OBJECTIVE

The objective was to examine the association of a vegetarian diet with risk of incident (nonfatal and fatal) IHD.

DESIGN

A total of 44,561 men and women living in England and Scotland who were enrolled in the European Prospective Investigation into Cancer and Nutrition (EPIC)-Oxford study, of whom 34% consumed a vegetarian diet at baseline, were part of the analysis. Incident cases of IHD were identified through linkage with hospital records and death certificates. Serum lipids and blood pressure measurements were available for 1519 non cases, who were matched to IHD cases by sex and age. IHD risk by vegetarian status was estimated by using multivariate Cox proportional hazards models.

RESULTS

After an average follow-up of 11.6 y, there were 1235 IHD cases (1066 hospital admissions and 169 deaths). Compared with nonvegetarians, vegetarians had a lower mean BMI [in kg/m(2); -1.2 (95% CI: -1.3, -1.1)], non-HDL-cholesterol concentration [-0.45 (95% CI: -0.60, -0.30) mmol/L], and systolic blood pressure [-3.3 (95% CI: -5.9, -0.7) mm Hg]. Vegetarians had a 32% lower risk (HR: 0.68; 95% CI: 0.58, 0.81) of IHD than did nonvegetarians, which was only slightly attenuated after adjustment for BMI and did not differ materially by sex, age, BMI, smoking, or the presence of IHD risk factors.

CONCLUSION

Consuming a vegetarian diet was associated with lower IHD risk, a finding that is probably mediated by differences in non-HDL cholesterol, and systolic blood pressure.

Prevalence of dyslipidemia and associated factors in the Yi farmers and migrants of Southwestern China

There are scant data on serum lipid profile in the Yi people in China. The Yi farmers and migrants provide an unusual opportunity to estimate effects of environmental factors on serum lipid levels. We conducted a cross-sectional study in the Yi people to estimate prevalence of dyslipidemia and associated factors. It was found that prevalence of high total cholesterol (TC), triglyceride (TG), low-density lipoprotein-cholesterol (LDL-C), abnormal ratio of TC/HDL-C and low high-density lipoprotein-cholesterol (HDL-C) were 1.82%, 5.07%, 1.56%, 9.30% and 39.47%, respectively in the Yi farmers. And those in the Yi migrants were 4.81%, 22.21%, 3.24%, 26.56% and 40.53%. Prevalence of dyslipidemia increased with time period in the Yi farmers after their emigrating to urban areas for less than 25 years, except high TC. It was also found that prevalence of dyslipidemia of the Yi migrants increased with time period before their emigration, including hypertriglyceridemia, low HDL-C and high ratio of TC/HDL-C. Their body mass index (BMI), history of type 2 diabetes mellitus (T2DM), gender, ever alcohol drinking and physical activity all were associated with dyslipidemia, but no factors associated with high LDL-C was found. In conclusion, all these results suggest that the Yi migrants have a higher prevalence of dyslipidemia than the Yi farmers do, which possibly can attribute to their urbanized lifestyles.

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.

Long-chain n-3 polyunsaturated fatty acids in plasma in British meat-eating, vegetarian, and vegan men

BACKGROUND

Plasma concentrations of long-chain n-3 polyunsaturated fatty acids are lower in vegetarians and in vegans than in omnivores. No data are available on whether these concentrations differ between long- and short-term vegetarians and vegans.

OBJECTIVES

We compared plasma fatty acid composition in meat-eaters, vegetarians, and vegans and examined whether the proportions of eicosapentaenoic acid (20:5n-3; EPA), docosapentaenoic acid (22:5n-3; DPA), and docosahexaenoic acid (22:6n-3; DHA) were related to the subjects' duration of adherence to their diets or to the proportions of plasma linoleic acid (18:2n-6; LA) and alpha-linolenic acid (18:3n-3; ALA).

DESIGN

The present cross-sectional study included 196 meat-eating, 231 vegetarian, and 232 vegan men in the United Kingdom. Information on anthropometry, diet, and smoking habits was obtained through a questionnaire. Total fatty acid composition in plasma was measured.

RESULTS

The proportions of plasma EPA and DHA were lower in the vegetarians and in the vegans than in the meat-eaters, whereas only small differences were seen for DPA. Plasma EPA, DPA, and DHA proportions were not significantly associated with the duration of time since the subjects became vegetarian or vegan, which ranged from <1 y to >20 y. In the vegetarians and the vegans, plasma DHA was inversely correlated with plasma LA.

CONCLUSIONS

The proportions of plasma long-chain n-3 fatty acids were not significantly affected by the duration of adherence to a vegetarian or vegan diet. This finding suggests that when animal foods are wholly excluded from the diet, the endogenous production of EPA and DHA results in low but stable plasma concentrations of these fatty acids.

Veganism and its relationship with insulin resistance and intramyocellular lipid

OBJECTIVE

To test the hypothesis that dietary factors in the vegan diet lead to improved insulin sensitivity and lower intramyocellular lipid (IMCL) storage.

DESIGN

Case-control study.

SETTING

Imperial College School of Medicine, Hammersmith Hospital Campus, London, UK.

SUBJECTS

A total of 24 vegans and 25 omnivores participated in this study; three vegan subjects could not be matched therefore the matched results are shown for 21 vegans and 25 omnivores. The subjects were matched for gender, age and body mass index (BMI).

INTERVENTIONS

Full anthropometry, 7-day dietary assessment and physical activity levels were obtained. Insulin sensitivity (%S) and beta-cell function (%B) were determined using the homeostatic model assessment (HOMA). IMCL levels were determined using in vivo proton magnetic resonance spectroscopy; total body fat content was assessed by bioelectrical impedance.

RESULTS

There was no difference between the groups in sex, age, BMI, waist measurement, percentage body fat, activity levels and energy intake. Vegans had a significantly lower systolic blood pressure (-11.0 mmHg, CI -20.6 to -1.3, P=0.027) and higher dietary intake of carbohydrate (10.7%, CI 6.8-14.5, P<0.001), nonstarch polysaccharides (20.7 g, CI 15.8-25.6, P<0.001) and polyunsaturated fat (2.8%, CI 1.0-4.6, P=0.003), with a significantly lower glycaemic index (-3.7, CI -6.7 to -0.7, P=0.01). Also, vegans had lower fasting plasma triacylglycerol (-0.7 mmol/l, CI -0.9 to -0.4, P<0.001) and glucose (-0.4 mmol/l, CI -0.7 to -0.09, P=0.05) concentrations. There was no significant difference in HOMA %S but there was with HOMA %B (32.1%, CI 10.3-53.9, P=0.005), while IMCL levels were significantly lower in the soleus muscle (-9.7, CI -16.2 to -3.3, P=0.01).

CONCLUSION

Vegans have a food intake and a biochemical profile that will be expected to be cardioprotective, with lower IMCL accumulation and beta-cell protective.

Mortality in British vegetarians: review and preliminary results from EPIC-Oxford

BACKGROUND

Three prospective studies have examined the mortality of vegetarians in Britain.

OBJECTIVE

We describe these 3 studies and present preliminary results on mortality from the European Prospective Investigation into Cancer and Nutrition-Oxford (EPIC-Oxford).

DESIGN

The Health Food Shoppers Study and the Oxford Vegetarian Study were established in the 1970s and 1980s, respectively; each included about 11 000 subjects and used a short questionnaire on diet and lifestyle. EPIC-Oxford was established in the 1990s and includes about 56 000 subjects who completed detailed food frequency questionnaires. Mortality in all 3 studies was followed though the National Health Service Central Register.

RESULTS

Overall, the death rates of all the subjects in all 3 studies are much lower than average for the United Kingdom. Standardized mortality ratios (95% CIs) for all subjects were 59% (57%, 61%) in the Health Food Shoppers Study, 52% (49%, 56%) in the Oxford Vegetarian Study, and 39% (37%, 42%) in EPIC-Oxford. Comparing vegetarians with nonvegetarians within each cohort, the death rate ratios (DRRs), adjusted for age, sex and smoking, were 1.03 (0.95, 1.13) in the Health Food Shoppers Study, 1.01 (0.89, 1.14) in the Oxford Vegetarian Study, and 1.05 (0.86, 1.27) in EPIC-Oxford. DRRs for ischemic heart disease in vegetarians compared with nonvegetarians were 0.85 (0.71, 1.01) in the Health Food Shoppers Study, 0.86 (0.67, 1.12) in the Oxford Vegetarian Study, and 0.75 (0.41, 1.37) in EPIC-Oxford.

CONCLUSIONS

The mortality of both the vegetarians and the nonvegetarians in these studies is low compared with national rates. Within the studies, mortality for major causes of death was not significantly different between vegetarians and nonvegetarians, but the nonsignificant reduction in mortality from ischemic heart disease among vegetarians was compatible with the significant reduction previously reported in a pooled analysis of mortality in Western vegetarians.

Changing from a mixed to self-selected vegetarian diet - influence on blood lipids

OBJECTIVE

To observe any changes in serum concentrations of lipids, when UK meat-eaters switch to a self selected vegetarian diet for 6 months.

DESIGN

Observational study using capillary blood samples and 3-day estimated dietary diary.

SETTING

Free-living subjects in the North-West of England.

SUBJECTS

Twelve male and 31 female adult volunteers aged between 18 and 42 years.

OUTCOME MEASURES

Serum lipids; nutrient intake and anthropometric measurements at baseline and 6 months after switching to a self-selected vegetarian diet.

RESULTS

Total energy intake and amount of energy derived from saturated fatty acids decreased significantly after changing to a vegetarian diet (P < 0.05) whereas energy derived from carbohydrate, and intakes of nonstarch polysaccharide intake increased. On switching to a vegetarian diet, total cholesterol and triacylglycerol concentrations were not significantly changed, but HDL-C was 21% higher than at baseline (1.21 mmol L(-1) vs. 1.47 mmol L(-1); P = 0.001).

CONCLUSIONS

These results suggest that beneficial changes to diet occurred on changing to a self-selected vegetarian diet. Changing to a self-selected vegetarian diet appears to be one way of achieving a better blood lipid profile.

Giessen Wholesome Nutrition Study: relation between a health-conscious diet and blood lipids

OBJECTIVE

To study in humans the relationship between a diet consistent with most of the current recommendations for the prevention of nutrition-related diseases (Wholesome Nutrition) and the blood lipid profile (total cholesterol, LDL-, HDL-cholesterol, LDL/HDL-ratio, triglycerides).

DESIGN

Cross-sectional study with two diet groups.

SETTING

Former West Germany.

SUBJECTS

Healthy women (n=243, aged 25-65 y) adhering to Wholesome Nutrition for at least 5 y (subdivided into 111 ovo-lacto vegetarians and 132 low-meat eaters) and an according control group of 175 women eating an average German mixed diet. They were all recruited through an advertisement campaign and selected on the basis of their food consumption.

RESULTS

Considering potential confounders, the Wholesome Nutrition subgroups had higher HDL-cholesterol levels than the control group. No differences were observed for total cholesterol and LDL-cholesterol. For LDL/HDL-ratio and triglycerides the effect of diet was dependent on interaction terms. With increasing risk factors (age or body mass index (BMI)) the Wholesome Nutrition subgroups showed more favourable blood lipids.

CONCLUSIONS

Women eating a preventive diet on a long-term basis exhibit more favourable blood lipid profiles than women consuming an average mixed diet. This is particularly obvious for HDL-cholesterol in the presence of certain risk factors and when an ovo-lacto vegetarian version is practised.

SPONSORSHIP

Eden Foundation, Bad Soden, Germany.

The nature of the association between diet and serum lipids in the community: a twin study

Diet is commonly thought to be an environmental influence on serum lipid concentrations. This study evaluated whether total caloric and fat intake predict total cholesterol (TC), low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), and triglyceride (TRIG) concentrations for environmental, as compared with genetic, reasons among 137 monozygotic and 67 dizygotic young adult twins. When genetic influences were controlled by correlating differences between monozygotic co-twins, a significant association remained between diet and TC, LDL, and HDL, suggesting that these dietary and serum lipid measures correlate for environmental reasons. Twin structural equation modeling confirmed these results. Overall, these results provide additional support for the hypothesis that diet is an environmental influence on TC, LDL, and HDL.

Cardiovascular risk factors in vegetarians. Normalization of hyperhomocysteinemia with vitamin B(12) and reduction of platelet aggregation with n-3 fatty acids

Hyperhomocysteinemia in association with vitamin B(12) deficiency, and increased platelet aggregation, probably due to dietary lack of n-3 fatty acids, constitute cardiovascular risk factors frequently observed in vegetarians. We tested if administration of vitamin B(12) normalizes the concentration of total plasma homocysteine, and if intake of eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3) fatty acids modulates platelet function in a population of lactoovovegetarians. One week after a single intramuscular injection of cyanocobalamin (10000 microg) in 18 individuals, serum vitamin B(12) increased from 149+/-63 pg/mL to 532+/-204 pg/mL (p<0.0001) and total tHcy dropped from 12.4+/-4.7 to 7.9+/-3.1 micromol/L (p<0. 0001). Ten of fourteen of these vegetarians completed an 8-week supplementation with 700 mg/day of each eicosapentaenoic and docosahexaenoic acids. Increased incorporation of these fatty acids into plasma lipids was observed in all of them, together with a significant reduction in maximum percentage or slope of platelet aggregation with all the agonists tested (ADP, epinephrin, collagen, arachidonic acid). No significant change in bleeding time was observed after n-3 fatty acid trial. Supplementation with vitamin B(12) and n-3 fatty acids corrects hyperhomocysteinemia and reduces platelet reactivity to agonists in vegetarians. Whether this supplementation improves the already reduced cardiovascular morbidity and mortality associated with vegetarian diet has yet to be demonstrated.

Frequency of food consumption and lipoprotein serum levels in the population of an urban area, Brazil

OBJECTIVE

To identify the association between food group consumption frequency and serum lipoprotein levels among adults.

METHODS

The observations were made during a cross-sectional survey of a representative sample of men and women over 20 years old living in Cotia county, S. Paulo, Brazil. Data on food frequency consumption, serum lipids, and other covariates were available for 1, 045 adults. Multivariate analyses adjusted by age, gender, body mass index, waist-to-hip ratio, educational level, family income, physical activity, smoking, and alcohol consumption were performed.

RESULTS

Consumption of processed meat, chicken, red meat, eggs and dairy foods were each positively and significantly correlated with LDL-C, whereas the intake of vegetables and fruits showed an inverse correlation. Daily consumption of processed meat, chicken, red meat, eggs, and dairy foods were associated with 16.6 mg/dl, 14.5 mg/dl, 11.1 mg/dl, 5.8 mg/dl, and 4.6 mg/dl increase in blood LDL-C, respectively. Increases of daily consumption of fruit and vegetables were associated with 5.2 mg/dl and 5.5 mg/dl decreases in LDL-C, respectively. Alcohol beverage consumption showed a significant positive correlation with HDL-C.

CONCLUSIONS

Dietary habits in the study population seem to contribute substantially to the variation in blood LDL and HDL concentrations. Substantially CHD risk reduction could be achieved with dietary changes.

Hormones and diet: low insulin-like growth factor-I but normal bioavailable androgens in vegan men

Mean serum insulin-like growth factor-I was 9% lower in 233 vegan men than in 226 meat-eaters and 237 vegetarians (P = 0.002). Vegans had higher testosterone levels than vegetarians and meat-eaters, but this was offset by higher sex hormone binding globulin, and there were no differences between diet groups in free testosterone, androstanediol glucuronide or luteinizing hormone.

Effects of a prudent diet containing either lean beef and mutton or fish and skinless chicken on the plasma lipoproteins and fatty acid composition of triacylglycerol and cholesteryl ester of hypercholesterolemic subjects11This study was sponsored by the Meat Board of South Africa

In this two-phase crossover study, 39 hypercholesterolemic subjects followed a prudent diet with either lean red meat or fish and skinless chicken (treatment groups), and 13 subjects (reference group) followed their habitual diet. Fasting blood samples were analyzed for plasma total cholesterol, triacylglycerol (TAG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein one- and two-cholesterol, apolipoprotein-B, very low density lipoprotein cholesterol, and very low density lipoprotein TAG, and fatty acid composition of plasma TAG and cholesteryl ester (CE). Body mass and blood pressure were determined. Seven-day dietary records were kept once at baseline and twice during the treatment periods. Significant differences were observed in dietary intake between the baseline and treatment diets and between the two treatment diets. HDL-C (P < 0.05) and diastolic blood pressure (P < 0.01) were higher in patients on the red meat diet than in those on the chicken-fish diet. No other significant differences in lipoproteins were observed between the effects of the two treatment diets. The linoleic acid (%), eicosapentaenoic acid (%), and the eicosapentaenoic acid/arachidonic acid ratios in TAG and CE were higher (P < 0.01) in subjects on the chicken-fish diet than in those on the red meat diet. In conclusion, this study showed that the effect of two lipid-lowering diets containing either lean red meat or skinless chicken and fish on the atherogenic lipoproteins did not differ significantly. A prudent diet with skinless chicken and fish, however, had a more favorable effect on the fatty acid composition of the plasma TAG and the CE than did the lean red meat diet.

The Oxford Vegetarian Study: an overview

The Oxford Vegetarian Study is a prospective study of 6000 vegetarians and 5000 nonvegetarian control subjects recruited in the United Kingdom between 1980 and 1984. Cross-sectional analyses of study data showed that vegans had lower total- and LDL-cholesterol concentrations than did meat eaters; vegetarians and fish eaters had intermediate and similar values. Meat and cheese consumption were positively associated, and dietary fiber intake was inversely associated, with total-cholesterol concentration in both men and women. After 12 y of follow-up, all-cause mortality in the whole cohort was roughly half that in the population of England and Wales (standardized mortality ratio, 0.46; 95% CI, 0.42, 0.51). After adjusting for smoking, body mass index, and social class, death rates were lower in non-meat-eaters than in meat eaters for each of the mortality endpoints studied [relative risks and 95% CIs: 0.80 (0. 65, 0.99) for all causes of death, 0.72 (0.47, 1.10) for ischemic heart disease, and 0.61 (0.44, 0.84) for all malignant neoplasms]. Mortality from ischemic heart disease was also positively associated with estimated intakes of total animal fat, saturated animal fat, and dietary cholesterol. Other analyses showed that non-meat-eaters had only half the risk of meat eaters of requiring an emergency appendectomy, and that vegans in Britain may be at risk for iodine deficiency. Thus, the health of vegetarians in this study is generally good and compares favorably with that of the nonvegetarian control subjects. Larger studies are needed to examine rates of specific cancers and other diseases among vegetarians.

Dietary intake and iron status of Australian vegetarian women

BACKGROUND

Despite the possible overall health benefits of a vegetarian diet, there is concern that some vegetarians and infrequent meat eaters, particularly females, may have inadequate iron status because of low or no heme-iron intakes.

OBJECTIVE

The objective was to investigate the nutritional intake and iron status of vegetarian women.

DESIGN

The nutritional intakes of 50 free-living vegetarian women aged 18-45 y and 24 age-matched omnivorous control women were assessed by using 12-d weighed dietary records. Iron status was assessed by measuring hemoglobin and serum ferritin concentrations.

RESULTS

There was no significant difference between mean (+/-SD) daily iron intakes of vegetarians and omnivores (10.7 +/- 4.4 and 9.9 +/- 2.9 mg, respectively), although heme-iron intakes were low in the vegetarians. Vegetarians had significantly lower intakes of protein (P < 0.01), saturated fat (P < 0.01), and cholesterol (P < 0.001), and significantly higher intakes of dietary fiber (P < 0.001) and vitamin C (P < 0.05). Mean serum ferritin concentrations were significantly lower (P = 0.025) in vegetarians (25.0 +/- 16.2 microg/L) than in omnivores (45.5 +/- 42.5 microg/L). However, similar numbers of vegetarians (18%) and omnivores (13%) had serum ferritin concentrations <12 microg/L, which is a value often used as an indicator of low iron stores. Hemoglobin concentrations were not significantly different.

CONCLUSION

It is important that both vegetarian and omnivorous women maintain an adequate iron status and follow dietary practices that enhance iron absorption.

Mortality in vegetarians and nonvegetarians: detailed findings from a collaborative analysis of 5 prospective studies

We combined data from 5 prospective studies to compare the death rates from common diseases of vegetarians with those of nonvegetarians with similar lifestyles. A summary of these results was reported previously; we report here more details of the findings. Data for 76172 men and women were available. Vegetarians were those who did not eat any meat or fish (n = 27808). Death rate ratios at ages 16-89 y were calculated by Poisson regression and all results were adjusted for age, sex, and smoking status. A random-effects model was used to calculate pooled estimates of effect for all studies combined. There were 8330 deaths after a mean of 10.6 y of follow-up. Mortality from ischemic heart disease was 24% lower in vegetarians than in nonvegetarians (death rate ratio: 0.76; 95% CI: 0.62, 0.94; P<0.01). The lower mortality from ischemic heart disease among vegetarians was greater at younger ages and was restricted to those who had followed their current diet for >5 y. Further categorization of diets showed that, in comparison with regular meat eaters, mortality from ischemic heart disease was 20% lower in occasional meat eaters, 34% lower in people who ate fish but not meat, 34% lower in lactoovovegetarians, and 26% lower in vegans. There were no significant differences between vegetarians and nonvegetarians in mortality from cerebrovascular disease, stomach cancer, colorectal cancer, lung cancer, breast cancer, prostate cancer, or all other causes combined.

Physical fitness and vegetarian diets: is there a relation?

The available evidence supports neither a beneficial nor a detrimental effect of a vegetarian diet on physical performance capacity, especially when carbohydrate intake is controlled for. Concerns have been raised that an emphasis on plant foods to enhance carbohydrate intake and optimize body glycogen stores may lead to increases in dietary fiber and phytic acid intake to concentrations that reduce the bioavailability of several nutrients, including zinc, iron, and some other trace minerals. There is no convincing evidence, however, that vegetarian athletes suffer impaired nutrient status from the interactive effect of their heavy exertion and plant-food based dietary practices to the extent that performance, health, or both are impaired. Although there has been some concern about protein intake for vegetarian athletes, data indicate that all essential and nonessential amino acids can be supplied by plant food sources alone as long as a variety of foods is consumed and the energy intake is adequate. There has been some concern that vegetarian female athletes are at increased risk for oligoamenorrhea, but evidence suggests that low energy intake, not dietary quality, is the major cause. In conclusion, a vegetarian diet per se is not associated with improved aerobic endurance performance. Although some concerns have been raised about the nutrient status of vegetarian athletes, a varied and well-planned vegetarian diet is compatible with successful athletic endeavor.

Oestradiol and sex hormone-binding globulin in premenopausal and post-menopausal meat-eaters, vegetarians and vegans

Endogenous oestradiol is strongly associated with breast cancer risk but its determinants are poorly understood. To test the hypothesis that vegetarians have lower plasma oestradiol and higher sex hormone-binding globulin (SHBG) than meat-eaters we assayed samples from 640 premenopausal women (153 meat-eaters, 382 vegetarians, 105 vegans) and 457 post-menopausal women (223 meat-eaters, 196 vegetarians, 38 vegans). Vegetarians and vegans had lower mean body mass indices (BMI) and lower plasma cholesterol concentrations than meat-eaters, but there were no statistically significant differences between meat-eaters, vegetarians and vegans in pre- or post-menopausal plasma concentrations of oestradiol or SHBG. Before adjusting for BMI there were small differences in the direction expected, with the vegetarians and vegans having higher SHBG and lower oestradiol (more noticeable amongst post-menopausal women) than the meat-eaters. These small differences were essentially eliminated by adjusting for BMI. Thus this study implies that the relatively low BMI of vegetarians and vegans does cause small changes in SHBG and in post-menopausal oestradiol, but that the composition of vegetarian diets may not have any additional effects on these hormones.

Health benefits of a vegetarian diet

Compared with non-vegetarians, Western vegetarians have a lower mean BMI (by about 1 kg/m2), a lower mean plasma total cholesterol concentration (by about 0.5 mmol/l), and a lower mortality from IHD (by about 25%). They may also have a lower risk for some other diseases such as constipation, diverticular disease, gallstones and appendicitis. No differences in mortality from common cancers have been established. There is no evidence of adverse effects on mortality. Much more information is needed, particularly on other causes of death, other morbidity including osteoporosis, and long-term health in vegans. The evidence available suggests that widespread adoption of a vegetarian diet could prevent approximately 40,000 deaths from IHD in Britain each year.

Mortality in vegetarians and non-vegetarians: a collaborative analysis of 8300 deaths among 76,000 men and women in five prospective studies

OBJECTIVE

To compare the mortality rates of vegetarians and non-vegetarians.

DESIGN

Collaborative analysis using original data from five prospective studies. Death rate ratios for vegetarians compared to non-vegetarians were calculated for ischaemic heart disease, cerebrovascular disease, cancers of the stomach, large bowel, lung, breast and prostate, and for all causes of death. All results were adjusted for age, sex and smoking. A random effects model was used to calculate pooled estimates of effect for all studies combined.

SETTING

USA, UK and Germany.

SUBJECTS

76,172 men and women aged 16-89 years at recruitment. Vegetarians were those who did not eat any meat or fish (n = 27,808). Non-vegetarians were from a similar background to the vegetarians within each study.

RESULTS

After a mean of 10.6 years of follow-up there were 8330 deaths before the age of 90 years, including 2264 deaths from ischaemic heart disease. In comparison with non-vegetarians, vegetarians had a 24% reduction in mortality from ischaemic heart disease (death rate ratio 0.76, 95% CI 0.62-0.94). The reduction in mortality among vegetarians varied significantly with age at death: rate ratios for vegetarians compared to non-vegetarians were 0.55 (95% CI 0.35-0.85), 0.69 (95% CI 0.53-0.90) and 0.92 (95% CI 0.73-1.16) for deaths from ischaemic heart disease at ages <65, 65-79 and 80-89 years, respectively. When the non-vegetarians were divided into regular meat eaters (who ate meat at least once a week) and semi-vegetarians (who ate fish only or ate meat less than once a week), the ischaemic heart disease death rate ratios compared to regular meat eaters were 0.78 (95% CI 0.68-0.89) in semi-vegetarians and 0.66 (95% CI 0.53-0.83) in vegetarians (test for trend P< 0.001). There were no significant differences between vegetarians and non-vegetarians in mortality from the other causes of death examined.

CONCLUSION

Vegetarians have a lower risk of dying from ischaemic heart disease than non-vegetarians.

Dietary determinants of ischaemic heart disease in health conscious individuals

OBJECTIVE

To investigate dietary determinants of ischaemic heart disease (IHD) in health conscious individuals to explain the reduced risk in vegetarians, and to examine the relation between IHD and body mass index (BMI) within the normal range.

DESIGN

Prospective observation of vegetarians, semi-vegetarians, and meat eaters for whom baseline dietary data, reported weight and height information, social class, and smoking habits were recorded.

SUBJECTS

10,802 men and women in the UK aged between 16 and 79, mean duration of follow up 13.3 years.

MAIN OUTCOME MEASURES

Death rate rations for IHD and total mortality in relation to dietary and other characteristics recorded at recruitment (reference category death rate = 100).

RESULTS

IHD mortality was less than half that expected from the experience reported for all of England and Wales. An increase in mortality for IHD was observed with increasing intakes of total and saturated animal fat and dietary cholesterol-death rate ratios in the third tertile compared with the first tertile: 329, 95% confidence interval (CI) 150 to 721; 277, 95% CI 125 to 613; 353, 95% CI 157 to 796, respectively. No protective effects were observed for dietary fibre, fish or alcohol. Within the study, death rate ratios were increased among those in the upper half of the normal BMI range (22.5 to < 25) and those who were overweight (BMI > or = 25) compared with those with BMI 20 to < 22.5.

CONCLUSIONS

In these relatively health conscious individuals the deleterious effects of saturated animal fat and dietary cholesterol appear to be more important in the aetiology of IHD than the protective effect of dietary fibre. Reduced intakes of saturated animal fat and cholesterol may explain the lower rates of IHD among vegetarians compared with meat eaters. Increasing BMI within the normal range is associated with increased risk of IHD. The results have important public health implications.

The dietary intake of a group of vegetarian children aged 7-11 years compared with matched omnivores

There is a lack of information concerning the diet of vegetarian children. The present study compared the dietary intake of fifty vegetarian children, aged 7-11 years, with fifty matched omnivores. Three 3 d food records were completed by each child at intervals of 6 months. The day after completing the record each child was interviewed to clarify food items and assess portion sizes. Food records were analysed using Microdiet (University of Salford). Finger-prick cholesterol and haemoglobin measurements were taken from a subsample of the group. Only one child's family was a member of the Vegetarian Society and almost one-third of vegetarian children had omnivorous parents (seventeen of fifty subjects). The energy intake (MJ) of the vegetarians was significantly lower than that of the omnivores, 7.6 (SD 1.05) and 8.0 (SD 1.36) respectively; there were no significant differences in Fe or fat intakes. For the vegetarians polyunsaturated:saturated fat ratio (P:S 0.7 (SD 0.04)) and NSP intake (13.8 (SD 0.7) g/d) were significantly higher than those of the omnivores (P:S 0.5 (SD 0.02), NSP 10.3 (SD 0.4) g/d). There was no significant difference in cholesterol measurements (mmol/l) between the two groups: vegetarian 3.5 (SD 0.12), omnivores 3.7 (SD 0.15). The haemoglobin level (g/l) of the vegetarians (11.8 (SD 0.2)) was significantly below that of the omnivores (12.4 (SD 0.2)); 47.5% of the vegetarian children fell below the third percentile of the Dallman reference curves (Dallman & Siimes, 1979). The intake of the vegetarians more closely resembled current recommendations (Department of Health, 1991), although they need to be as aware as omnivores of the need to reduce fat intake. The haemoglobin levels of vegetarian children suggest that they need dietary advice to ensure optimal absorption of Fe.

Serum lipid and apolipoprotein distributions in Hong Kong Chinese

STUDY OBJECTIVE

The aim was to describe the distribution of lipids and apolipoproteins in the Chinese population in Hong Kong.

DESIGN

This was a prospective, cross sectional, population based survey.

SETTINGS

The study was conducted in a single, self referred, out patient screening centre.

PARTICIPANTS

Altogether 825 Chinese adults aged > or = 20 years were screened. One hundred subjects who had previously had lipid measurement and 29 who were taking lipid modifying drugs were excluded but 289 men and 407 women remained for further analysis.

MAIN RESULTS

Age standardised mean (SEM) lipids concentrations for Hong Kong Chinese were total cholesterol: men, 5.48 (0.05) mmol/l and women, 5.46 (0.06) mmol/l; triglycerides: men, 1.22 (1.03) mmol/l and women, 1.00 (1.03) mmol/l; high density lipoprotein (HDL) cholesterol: men, 1.25 (0.02) mmol/l and women, 1.42 (0.02) mmol/l; low density lipoprotein (LDL) cholesterol: men, 3.56 (0.05) mmol/l and women, 3.50 (0.06) mmol/l; apolipoprotein A-I (apo A-I): men, 1.34 (0.01) g/l and women, 1.46 (0.01) g/l; and apolipoprotein B (apo B): men, 1.15 (0.02) g/l and women, 1.06 (0.02) g/l. The total to HDL cholesterol ratios were men, 4.62 (0.07) and women, 4.10 (0.08); and apo B to apo A-I ratios (apo B/A) were men, 0.88 (0.02) and women, 0.75 (0.02). While levels of total cholesterol, LDL cholesterol, apo B, triglycerides, total/HDL cholesterol, and apo B/A were positively associated with age in both sexes and were higher in men before the age 50-59 years, they rose steeply thereafter in women to cross over the levels in men. In contrast, HDL cholesterol decreased with age while apo A-I remained constant, and both were consistently higher in women than in men in all age groups.

CONCLUSIONS

Hong Kong Chinese have attained lipid profiles similar to those in other developed western populations. Environmental factors seem influential in this regard. Faced with the increasing coronary mortality of recent years, there should be a major effort to reduce the cholesterol concentrations in this population.

Risk of death from cancer and ischaemic heart disease in meat and non-meat eaters

OBJECTIVE

To investigate the health consequences of a vegetarian diet by examining the 12 year mortality of non-meat eaters and meat eating controls.

DESIGN

Prospective observational study in which members of the non-meat eating cohort were asked to nominate friends or relatives as controls.

SETTING

United Kingdom.

SUBJECTS

6115 non-meat eaters identified through the Vegetarian Society of the United Kingdom and the news media (mean (SD) age 38.7 (16.8) years) and 5015 controls who were meat eaters (39.3 (15.4) years).

MAIN OUTCOME MEASURES

Standardised mortality ratios for cancer, ischaemic heart disease, and total mortality in the two cohorts and death rate ratio in the non-meat eaters compared with meat eaters after adjustment for potentially confounding variables.

RESULTS

Standardised mortality ratios (taking the value among the general population as 100) for ischaemic heart disease were 51 (95% confidence interval 38 to 66) for meat eaters and 28 (20 to 38) for non-meat eaters (P < 0.01). Values for all cancers were 80 (64 to 98) and 50 (39 to 62) for meat eaters and non-meat eaters respectively. After adjustment for the effects of smoking, body mass index, and socioeconomic status death rate ratios in non-meat eaters compared with meat eaters were 0.72 (0.47 to 1.10) for ischaemic heart disease and 0.61 (0.44 to 0.84) for all cancers.

CONCLUSIONS

The reduced mortality from cancer among those not eating meat is not explained by lifestyle related risk factors, which have a low prevalence among vegetarians. No firm conclusion can be made about deaths from ischaemic heart disease. These data do not justify advice to exclude meat from the diet since there are several attributes of a vegetarian diet apart from not eating meat which might reduce the risk.

Distribution of lipid variables in subjects in Belfast, Northern Ireland and Taiyuan, P R China

To compare the plasma lipid, lipoprotein and apolipoprotein profiles of people of Chinese and European origin, a sample of 151 male Chinese subjects was selected from Taiyuan, Shanxi Province, P R China to 202 broadly age-matched subjects in Belfast who were selected as controls in a case-control study of myocardial infarction. Mean total cholesterol (TC) was 6.15 mmol/l in Belfast and 4.28 mmol/l in Taiyuan. Low density lipoprotein cholesterol (LDL) was much higher in Belfast. High density lipoprotein cholesterol (LDL) was also higher in Belfast than in Taiyuan but the ratio of HDL to TC was lower in Belfast than Taiyuan. Triglyceride (TG) levels were similar and this was reflected in the relatively high level of apolipoprotein E (apo E) in the Chinese sample.