Abstract
Results associating diet with chronic disease in a cohort of 34 192 California Seventh-day Adventists are summarized. Most Seventh-day Adventists do not smoke cigarettes or drink alcohol, and there is a wide range of dietary exposures within the population. About 50% of those studied ate meat products <1 time/wk or not at all, and vegetarians consumed more tomatoes, legumes, nuts, and fruit, but less coffee, doughnuts, and eggs than did nonvegetarians. Multivariate analyses showed significant associations between beef consumption and fatal ischemic heart disease (IHD) in men [relative risk (RR) = 2.31 for subjects who ate beef ≥3 times/wk compared with vegetarians], significant protective associations between nut consumption and fatal and nonfatal IHD in both sexes (RR ≈0.5 for subjects who ate nuts ≥5 times/wk compared with those who ate nuts <1 time/wk), and reduced risk of IHD in subjects preferring whole-grain to white bread. The lifetime risk of IHD was reduced by ≈31% in those who consumed nuts frequently and by 37% in male vegetarians compared with nonvegetarians. Cancers of the colon and prostate were significantly more likely in nonvegetarians (RR of 1.88 and 1.54, respectively), and frequent beef consumers also had higher risk of bladder cancer. Intake of legumes was negatively associated with risk of colon cancer in nonvegetarians and risk of pancreatic cancer. Higher consumption of all fruit or dried fruit was associated with lower risks of lung, prostate, and pancreatic cancers. Cross-sectional data suggest vegetarian Seventh-day Adventists have lower risks of diabetes mellitus, hypertension, and arthritis than nonvegetarians. Thus, among Seventh-day Adventists, vegetarians are healthier than nonvegetarians but this cannot be ascribed only to the absence of meat. Am J Clin Nutr 1999;70(suppl):532S-8S.
Generated Summary
This research article presents a summary of findings from a cohort study of 34,192 non-Hispanic white California Seventh-day Adventists, focusing on the associations between diet and chronic diseases. The study, approved by the Loma Linda University ethics review committee, utilized a detailed lifestyle questionnaire mailed in 1976 to identify dietary habits. The subjects were monitored for cancer incidence and mortality over a 6-year follow-up period (1976-1988). The Adventist population provided a unique opportunity for this research due to their wide range of dietary habits, with a significant portion being vegetarian or semi-vegetarian, allowing for comparisons of dietary patterns within a population that largely avoids smoking and alcohol consumption. The core methodology included the collection of dietary data via food-frequency questionnaires, surveillance for new cancer and ischemic heart disease (IHD) cases, and record linkage with hospital records and tumor registries to confirm diagnoses. The study aimed to identify the relationships between various food consumption patterns and the risks of cancer, IHD, and all-cause mortality. The study’s findings highlighted the impact of dietary choices on health outcomes within this specific population.
Key Findings & Statistics
- Approximately 50% of the studied population consumed meat products less than once per week or not at all.
- Vegetarians consumed more tomatoes, legumes, nuts, and fruit but less coffee, doughnuts, and eggs than nonvegetarians.
- The study defined three dietary categories: vegetarian (no meat, fish, or poultry), semi-vegetarian (fish and poultry, but <1 time/wk), and nonvegetarian.
- About 20% were meat eaters who ate meat < 1 time/wk and about 30% ate no meat products.
- Non-Hispanic white subjects were monitored for a total of 6 y of follow-up.
- Cancer incidence among 34198 non-Hispanic white subjects was monitored for a total of 6 y of follow-up.
- The lifetime risk of IHD was reduced by ≈31% in those who consumed nuts frequently and by 37% in male vegetarians compared with nonvegetarians.
- The risk of a fatal IHD event in men was significantly related to beef consumption; those who consumed beef ≥3 times/wk had a 2.31-fold greater risk than did the vegetarian men. (P < 0.0001).
- In men, the risk of fatal IHD was significantly associated with beef consumption (RR = 2.31 for those who ate beef ≥3 times/wk compared with vegetarians).
- Those who consumed nuts 4-5 times/wk had only ≈50% of the risk of those who ate nuts ≤1 time/wk.
- Nonvegetarians had a higher risk of colon and prostate cancers (RR of 1.88 and 1.54, respectively), and frequent beef consumers also had a higher risk of bladder cancer.
- Frequent beef consumers had an 88% higher risk of colon cancer (P < 0.003).
- Vegetarians showed a 37% reduction in IHD risk compared to nonvegetarians.
- The lifetime risk of IHD was reduced by approximately 31% in those who consumed nuts frequently and by 37% in male vegetarians.
- Obesity, as measured by body mass index, increased with meat consumption, with a 1.78-m tall male non-vegetarian weighing 6.4 kg more on average than a vegetarian (P < 0.0001).
- The prevalences of hypertension and diabetes were both approximately 2-fold greater in nonvegetarians than vegetarians.
- Among men, the risk of a fatal IHD event was significantly related to beef consumption; those consuming beef ≥3 times/wk had a 2.31-fold greater risk than vegetarians (P < 0.0001).
- Vegetarians ate no meat, fish, or poultry; semivegetarians ate meat, fish, or poultry in total <1 time/wk; nonvegetarians ate these foods ≥1 time/wk.
- The lifetime risk of IHD was reduced by approximately 31% in those who consumed nuts frequently and by 37% in male vegetarians compared with nonvegetarians.
- The relative risk for total mortality for vegetarians was 0.80 (95% CI: 0.74, 0.87) compared to meat-eaters.
- Nonvegetarians ate meat 4.25 times per week.
- Vegetarian women lived 2.52 years longer than meat-eating women, and men lived 3.21 years longer.
- The risk of prostate cancer was 54% greater in the non-vegetarians (P ≈0.03).
Other Important Findings
- Vegetarian Seventh-day Adventists consumed more tomatoes, legumes, nuts, and fruit, but less coffee, doughnuts, and eggs compared to nonvegetarians.
- Multivariate analyses revealed significant associations between beef consumption and fatal ischemic heart disease (IHD) in men.
- Significant protective associations were found between nut consumption and fatal and nonfatal IHD in both sexes.
- A reduced risk of IHD was observed in subjects preferring whole-grain bread over white bread.
- Cancers of the colon and prostate were more likely in nonvegetarians.
- Frequent beef consumers had a higher risk of bladder cancer.
- Legume intake was negatively associated with colon cancer risk in nonvegetarians and pancreatic cancer risk.
- Higher consumption of all fruit or dried fruit was associated with lower risks of lung, prostate, and pancreatic cancers.
- Vegetarian Seventh-day Adventists showed lower risks of diabetes mellitus, hypertension, and arthritis compared to nonvegetarians.
- Vegetarians were healthier than nonvegetarians, though not solely attributable to the absence of meat.
- Nonfatal myocardial infarction was also defined by the international diagnostic criteria.
- The risk of a fatal IHD event in men was significantly related to beef consumption.
- The food most consistently associated with a reduced risk of both fatal and nonfatal IHD was nuts.
- Preference for whole-grain bread was also associated with reduced risk of IHD.
- Traditional risk factors for IHD were also seen in this cohort.
- The risk of prostate cancer was 54% greater in the non-vegetarians.
- Both colon and prostate cancer were significantly more common among nonvegetarian Seventh-day Adventists.
- Consumption of fruits, nuts, and grains were linked to lower risks of IHD and cancer.
Limitations Noted in the Document
- The study’s cross-sectional design limits the ability to establish causal relationships definitively.
- Data on dietary habits were collected via self-reported questionnaires, which may be subject to recall bias and other inaccuracies.
- The study primarily focused on a specific population (Seventh-day Adventists) which may limit the generalizability of the findings to other populations.
- The study was observational, and thus, the results are subject to potential confounding factors that were not fully accounted for.
- The analysis of specific food groups may not fully capture the complex interplay of nutrients and other factors that influence health outcomes.
- The study may not have had sufficient statistical power to detect small effects for certain cancers or other diseases.
Conclusion
The study’s findings underscore the significant influence of dietary choices on health outcomes, particularly within a population like Seventh-day Adventists, where diverse dietary habits exist. The results suggest that vegetarian diets, characterized by lower meat consumption and higher intake of fruits, vegetables, nuts, and whole grains, are associated with lower risks of several chronic diseases, including IHD and certain cancers. The protective effects of nut consumption and whole-grain bread against IHD were particularly noteworthy. The increased risk of colon and prostate cancers among nonvegetarians, along with the association between beef consumption and IHD in men, further highlight the health implications of dietary choices. These findings reinforce the importance of dietary factors in promoting longevity and reducing the burden of chronic diseases. While the study acknowledges that the observed benefits of vegetarian diets might not solely be attributable to the absence of meat, the associations between specific food groups and health outcomes suggest that dietary patterns significantly influence disease risk. The documented differences in health outcomes between vegetarian and nonvegetarian Seventh-day Adventists emphasize the potential of dietary interventions to improve public health, underscoring the need for further research on these dietary patterns and their impact on the prevention of chronic diseases. “The findings strongly suggest that dietary factors have an important influence on longevity and the risk of a number of chronic diseases.” Moreover, the study’s findings stress the importance of promoting dietary habits that are aligned with established guidelines for disease prevention, as well as the need for additional investigation to fully understand the complex relationships between diet and health.
IFFS Team Summary
- 34000 subjects followed, 50% were vegetarian or ate meat < once per week, meat eaters ate 3 or more times per week
- case controlled and followed 12 years
- vegetarian group ate some eggs and most did have dairy
- non vegetarian group ate meat half as much as average Californian
- vegetarian men lived 3.21 years longer and women 2.52 years longer
- decreased cardiovascular death in vegetarian males by 37%
- increased colon cancer RR 1.88 in non vegetarians, prostate cancer 1.54 in non vegetarians
- legumes associated with decreased colon and pancreatic cancer, nuts with decreased heart disease, fruits and vegetables with decreased prostate, lung and colon cancers
- decreased diabetes, hypertension, arthritis in vegetarians
- benefits partly attributed to absence of meat, partly due to higher intake of foods listed above