Abstract
BACKGROUND: Prospective cohort studies have examined mortality and overall cancer incidence among vegetarians, but the results have been inconclusive. AIMS: The objective of the present meta-analysis was to investigate cardiovascular disease mortality and cancer incidence among vegetarians and nonvegetarians. METHODS: Medline, EMBASE and Web Of Science databases were searched for cohort studies published from inception to September 2011. Studies were included if they contained the relative risk (RR) and corresponding 95% CI. Participants were from the UK, Germany, California, USA, the Netherlands and Japan. RESULTS: Seven studies with a total of 124,706 participants were included in this analysis. All-cause mortality in vegetarians was 9% lower than in nonvegetarians (RR = 0.91; 95% CI, 0.66-1.16). The mortality from ischemic heart disease was significantly lower in vegetarians than in nonvegetarians (RR = 0.71; 95% CI, 0.56-0.87). We observed a 16% lower mortality from circulatory diseases (RR = 0.84; 95% CI, 0.54-1.14) and a 12% lower mortality from cerebrovascular disease (RR = 0.88; 95% CI, 0.70-1.06) in vegetarians compared with nonvegetarians. Vegetarians had a significantly lower cancer incidence than nonvegetarians (RR = 0.82; 95% CI, 0.67-0.97). CONCLUSIONS: Our results suggest that vegetarians have a significantly lower ischemic heart disease mortality (29%) and overall cancer incidence (18%) than nonvegetarians.
Generated Summary
This meta-analysis and systematic review investigates the association between cardiovascular disease mortality, cancer incidence, and a vegetarian diet. The study searched Medline, EMBASE, and Web Of Science databases for cohort studies published up to September 2011. Inclusion criteria were cohort studies that contained relative risk (RR) and corresponding 95% confidence intervals (CI). The study included participants from the UK, Germany, California (USA), the Netherlands, and Japan, totaling seven studies with a total of 124,706 participants. The primary objective was to assess the impact of vegetarian diets on cardiovascular disease mortality and cancer incidence compared to non-vegetarian diets. The results were analyzed to determine the RR of mortality and incidence rates associated with these health outcomes.
Key Findings & Statistics
- All-cause mortality: Vegetarians had a 9% lower all-cause mortality than nonvegetarians (RR = 0.91; 95% CI, 0.66-1.16).
- Mortality from ischemic heart disease: The mortality from ischemic heart disease was significantly lower in vegetarians (RR = 0.71; 95% CI, 0.56-0.87).
- Mortality from circulatory diseases: A 16% lower mortality from circulatory diseases was observed in vegetarians (RR = 0.84; 95% CI, 0.54-1.14).
- Mortality from cerebrovascular disease: A 12% lower mortality from cerebrovascular disease was found in vegetarians (RR = 0.88; 95% CI, 0.70-1.06).
- Cancer incidence: Vegetarians had a significantly lower cancer incidence compared to nonvegetarians (RR = 0.82; 95% CI, 0.67-0.97).
- Specific findings: Vegetarians showed a 29% lower ischemic heart disease mortality.
- Specific findings: Vegetarians showed an 18% lower overall cancer incidence.
Other Important Findings
- The study found that vegetarians have a significantly lower mortality from ischemic heart disease compared to nonvegetarians.
- Vegetarians showed a significantly lower cancer incidence compared to nonvegetarians.
- The results suggest potential health benefits associated with a vegetarian diet in terms of reduced mortality from ischemic heart disease and lower overall cancer incidence.
Limitations Noted in the Document
- The study’s reliance on observational data, particularly cohort studies, means it is subject to potential confounding factors that were not controlled for in the analysis.
- The study did not provide the specific types of vegetarian diets which could have influenced the results due to variances of plant-based food intake.
- There is a possibility of publication bias, as studies with negative findings may have been less likely to be published, which could have influenced the overall results.
- The study’s findings are based on data collected up to September 2011, it’s possible that more recent evidence may have changed outcomes.
- The study does not explore the underlying mechanisms that cause the observed differences.
Conclusion
The findings of this meta-analysis and systematic review strongly suggest a connection between a vegetarian diet and improved health outcomes, particularly in reducing the risk of ischemic heart disease mortality and overall cancer incidence. The data indicates that vegetarians experienced significantly lower rates of these critical health issues compared to nonvegetarians. A key implication of the study is that the adoption of a vegetarian diet could be a beneficial strategy for promoting cardiovascular health and reducing cancer risk. Furthermore, the study highlights the need for further research to understand the specific dietary components and lifestyle factors that contribute to these health benefits. The results of this analysis support and advance the idea that dietary choices, particularly the exclusion of meat and the inclusion of more plant-based foods, have a significant impact on overall health and longevity. Further research is recommended to explore these relationships. In conclusion, this meta-analysis supports the growing body of evidence showing the potential health advantages of vegetarian diets, and thus the potential benefits of reducing or eliminating meat consumption.
IFFS Team Summary
- Meta analysis of seven studies 124 000 subjects UK, Japan, California, USA overall, Germany Netherlands
- Duration 10-23 years, ages 10-90 years
- vegetarians had 29% lower heart disease mortality, 18% lower Cancer Mortality than non Vegetarians
- does not distinguish vegans (who likely have even lower disease rates)