Abstract
IMPORTANCE: Some evidence suggests vegetarian dietary patterns may be associated with reduced mortality, but the relationship is not well established. OBJECTIVE: To evaluate the association between vegetarian dietary patterns and mortality. DESIGN: Prospective cohort study; mortality analysis by Cox proportional hazards regression, controlling for important demographic and lifestyle confounders. SETTING: Adventist Health Study 2 (AHS-2), a large North American cohort. PARTICIPANTS: A total of 96,469 Seventh-day Adventist men and women recruited between 2002 and 2007, from which an analytic sample of 73,308 participants remained after exclusions. EXPOSURES: Diet was assessed at baseline by a quantitative food frequency questionnaire and categorized into 5 dietary patterns: nonvegetarian, semi-vegetarian, pesco-vegetarian, lacto-ovo- vegetarian, and vegan. MAIN OUTCOME AND MEASURE: The relationship between vegetarian dietary patterns and all- cause and cause-specific mortality; deaths through 2009 were identified from the National Death Index. RESULTS: There were 2570 deaths among 73,308 participants during a mean follow-up time of 5.79 years. The mortality rate was 6.05 (95% CI, 5.82-6.29) deaths per 1000 person-years. The adjusted hazard ratio (HR) for all-cause mortality in all vegetarians combined vs nonvegetarians was 0.88 (95% CI, 0.80-0.97). The adjusted HR for all-cause mortality in vegans was 0.85 (95% CI, 0.73-1.01); in lacto-ovo-vegetarians, 0.91 (95% CI, 0.82-1.00); in pesco-vegetarians, 0.81 (95% CI, 0.69-0.94); and in semi-vegetarians, 0.92 (95% CI, 0.75-1.13) compared with nonvegetarians. Significant associations with vegetarian diets were detected for cardiovascular mortality, noncardiovascular noncancer mortality, renal mortality, and endocrine mortality. Associations in men were larger and more often significant than were those in women. CONCLUSIONS AND RELEVANCE: Vegetarian diets are associated with lower all-cause mortality and with some reductions in cause-specific mortality. Results appeared to be more robust in males. These favorable associations should be considered carefully by those offering dietary guidance.
Generated Summary
This is a prospective cohort study that examines the association between different vegetarian dietary patterns and mortality. The study, known as Adventist Health Study 2 (AHS-2), focuses on a large North American cohort of Seventh-day Adventists, a population with a high prevalence of vegetarianism. The primary objective is to evaluate how vegetarian dietary patterns relate to all-cause and cause-specific mortality. The methodology involves assessing dietary intake through a quantitative food frequency questionnaire, categorizing participants into various dietary patterns (nonvegetarian, semi-vegetarian, pesco-vegetarian, lacto-ovo-vegetarian, and vegan), and analyzing mortality data through Cox proportional hazards regression. The study aims to control for demographic and lifestyle factors to isolate the effect of diet on mortality outcomes. The research seeks to provide evidence on whether vegetarian diets are associated with reduced mortality, a topic that has garnered interest due to the potential health benefits of plant-based diets. This research contributes to the broader understanding of the health implications of dietary choices, especially in the context of vegetarianism, and how it influences mortality rates.
Key Findings & Statistics
- The study included 73,308 participants with a mean follow-up time of 5.79 years.
- There were 2570 deaths during the follow-up period.
- The mortality rate was 6.05 deaths per 1000 person-years (95% CI, 5.82-6.29).
- The adjusted hazard ratio (HR) for all-cause mortality in all vegetarians combined vs nonvegetarians was 0.88 (95% CI, 0.80-0.97). This indicates that vegetarians had a lower risk of all-cause mortality compared to nonvegetarians.
- The adjusted HR for all-cause mortality in vegans was 0.85 (95% CI, 0.73-1.01) compared to nonvegetarians.
- The adjusted HR for all-cause mortality in lacto-ovo-vegetarians was 0.91 (95% CI, 0.82-1.00) compared to nonvegetarians.
- The adjusted HR for all-cause mortality in pesco-vegetarians was 0.81 (95% CI, 0.69-0.94) compared to nonvegetarians.
- The adjusted HR for all-cause mortality in semi-vegetarians was 0.92 (95% CI, 0.75-1.13) compared to nonvegetarians.
- Significant associations with vegetarian diets were detected for cardiovascular mortality, noncardiovascular noncancer mortality, renal mortality, and endocrine mortality.
Other Important Findings
- Significant associations between vegetarian diets and reduced mortality were observed for cardiovascular mortality, noncardiovascular noncancer mortality, renal mortality, and endocrine mortality.
- Associations were more pronounced and frequently significant in men compared to women.
Limitations Noted in the Document
- The study’s reliance on a specific cohort (Seventh-day Adventists) may limit the generalizability of the findings to broader populations.
- The study design is observational, which means it can show associations but cannot definitively prove causality.
- The food frequency questionnaire might have inherent limitations in accurately capturing individual dietary intake.
- The study did not adjust for all potential confounders, leaving room for residual confounding.
- The study period might not be long enough to fully capture long-term mortality effects.
Conclusion
The study concludes that vegetarian diets are associated with lower all-cause mortality and some reductions in cause-specific mortality. The findings support the idea that adopting a vegetarian diet can contribute to improved health outcomes. The study’s results, specifically the reduced mortality rates among vegetarians, align with the growing body of evidence highlighting the health benefits of plant-based diets. The fact that the associations were more prominent in men suggests that dietary interventions might have differential effects based on sex. The research underscores the need for careful consideration when offering dietary guidance and emphasizes the importance of further investigation into the specific mechanisms by which vegetarian diets influence health. The consistent findings across various vegetarian subgroups, such as vegans, lacto-ovo-vegetarians, and pesco-vegetarians, suggest that the benefits are not limited to a single type of vegetarian diet. The overall implication is that promoting vegetarian diets could be a valuable strategy for enhancing public health and reducing mortality rates. The study’s findings reinforce the relevance of dietary choices in managing health and longevity, providing a strong foundation for future research in the field.
IFFS Team Summary
- 73 000 Seventh Day Adventists followed for a mean of 5.8 years only, recruited 2002-2007. 2570 deaths calculated up to 2009.
- Vegan, Vegetarian, Fish eaters, and semi-vegetarians have benefit over non-vegetarians HR = 0.85, 0.91, 0.81, 0.92 Respectively)
- modest 10% reduction in cancers and 18% decrease in heart disease
- Study is ongoing, and requires more time for better statistical significance between the groups
DOI
10.1001/jamainternmed.2013.8173