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Vegetarian diets associated with lower mortality, including CVD-related death

Orlich MJ, Singh PN, Sabaté J et al. - JAMA Intern Med 2013 ;():1-8


Vegetarian Dietary Patterns and Mortality in Adventist Health Study 2


Orlich MJ, Singh PN, Sabaté J et al.
JAMA Intern Med 2013 ;():1-8. doi:10.1001/jamainternmed.2013.6473.  Online first
 

Background

Several studies have investigated the relationship between dietary factors and mortality. For instance nuts, fruit, cereal fiber, polyunsaturated fatty acids (PUFAs), ω-3PUFAs, green salad, Mediterranean dietary patterns, plant-based diet scores and vegetarian diets have been found to be correlated with reduced mortality. In contrast, high glycemic load, processed or red meat, eggs, potatoes and animal-based low-carbohydrate diets, among other dietary factors, have been associated with increased mortality.
Vegetarian diets have been linked to reduced risk for several chronic diseases, including hypertension [1,2], metabolic syndrome [3], diabetes mellitus [4,5] and ischemic heart disease (IHD)[6,7]. This could result in lower mortality, but mixed results on the relationship between vegetarian dietary patterns and mortality have been published.
 This study aimed to evaluate the possible association of vegetarian dietary patterns with reduced mortality in the Adventist Health Study 2 (AHS-2), in a cohort of 73308 Seventh –day Adventists [8]. According to the reported intake of foods of animal origin, participants were divided into vegans (7.6%), lacto-ovo-vegetarians (eggs/dairy >1x/month, other meats <1x/mo, 28.9%), pesco-vegetarians (fish >1x/mo, other meats <1x/mo, 9.8%), semi-vegetarians (nonfish meats >1x/mo and all meats combined >1x/mo but not more than 1x/wk, 5.5%), and nonvegetarians (nonfish meats >1x/mo and all meats combined >1x/wk, 48.2%). Mean follow-up time was 5.79 (SD: 1.31) years, in which 2570 people passed away (6.05 deaths per 1000 person-years).
 

Main results

 

Conclusion

Overall, vegetarian dietary patterns were associated with lower mortality, as compared to nonvegetarian diets. Some associations demonstrated a specific benefit for cardiovascular mortality. Effects were generally stronger in men than in women.
 

Editorial comment [9]

This study supports evidence that vegetarian diets are associated with improved health outcomes. However, although well-performed, an observational study cannot provide cause-and-effect evidence. Another limitation of this study is the large variety of diets consumed by those identified as vegetarians, and that no information is provided on the overall quality or quantity of the diet. In addition to or even stronger than achievement of beneficial health outcomes, religious, ethical or environmental beliefs may motivate somebody to decrease meat intake. These factors should all be considered when giving dietary advice. However, for most patients, the primary nutritional goal is to control calories and prevent weight gain. It may be more important to help patients follow more common features of diets associated with good clinical outcomes than to focus on whether to include moderate amounts of dairy, eggs, fish or even meat.
 

References

1.Pettersen BJ, Anousheh R, Fan J et al. Vegetarian diets and blood pressure among white subjects: results from the AdventistHealth Study-2 (AHS-2). Public Health Nutr. 2012;15(10):1909-1916.
2. Appleby PN, Davey GK, Key TJ. Hypertension and blood pressure among meat eaters, fish eaters, vegetarians and vegans in EPIC-Oxford. Public Health Nutr.2002;5(5):645-654.
3. Rizzo NS, Sabate´ J, Jaceldo-Siegl K, Fraser GE. Vegetarian dietary patterns are associated with a lower risk of metabolic syndrome: the Adventist Health Study 2. Diabetes Care. 2011;34(5):1225-1227.
4. Tonstad S, Butler TL, Yan R, Fraser GE. Type of vegetarian diet, body weight,and prevalence of type 2 diabetes. Diabetes Care. 2009;32(5):791-796.
5. Tonstad S, Stewart K, Oda K, et al. Vegetarian diets and incidence of diabetes in the Adventist Health Study-2. Nutr Metab Cardiovasc Dis. 2013;23(4):292-299.
6. Fraser GE. Associations between diet and cancer, ischemic heart disease, and all-cause mortality in non-Hispanic white California Seventh-day Adventists. Am J Clin Nutr. 1999;70(3)(suppl):532S-538S.26.
7. Fraser GE. Diet and the risk of coronary heart disease. In: Fraser GE, ed. Diet, Life Expectancy, and Chronic Disease. New York, NY: Oxford University Press; 2003:59-84.
8. Butler TL, Fraser GE, Beeson WL, et al. Cohort profile: the Adventist Health Study-2 (AHS-2). Int J Epidemiol. 2008;37(2):260-265.
9. Baron RB. Should we all be vegetarians? JAMA Intern Med. 2013;():1-2. doi:10.1001/jamainternmed.2013.6972.
 

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