Seventh-Day Adventists, including black Adventists, may enjoy longer, cancer-free lifespans than the general US population, and their healthy lifestyles may contribute to this, say researchers in a study published online yesterday in the journal Cancer.
Seventh-Day Adventists follow a healthy lifestyle as part of their religion. For many, that includes a vegetarian diet, not smoking, not drinking alcohol, limiting caffeine, getting regular exercise, and maintaining a healthy weight/body mass index. Social and religious factors that may boost social support and community may also play a role.
"Adventist vegetarians have less overweight, diabetes, hypertension, elevated blood cholesterol, coronary heart disease, and several cancers compared with Adventist nonvegetarians, who themselves are lower-than-usual consumers of animal foods," author Gary Fraser, MBChB, PhD, professor of medicine at Loma Linda University in California, said in a press release.
Exceptional Longevity "Blue Zone"
Previous research has also suggested that Adventists have longer life spans than the general US population. Loma Linda, California, a center for Seventh-Day Adventism in the US, has been designated a so-called "blue zone" because of the exceptional longevity of its inhabitants — up to 10 years longer than the general US population.
Much of this longevity has been attributed to healthier lifestyles among Seventh-Day Adventists. But until now no nationwide comparison existed, particularly for blacks. The study is the first to compare cancer rates and death among Adventists to the larger US population, and the first to conduct a separate comparison for blacks.
In the US, the life expectancy for blacks is about 1.6 years shorter than for whites. The new study suggests that adopting a healthy lifestyle could increase life expectancy in blacks as well as whites.
However, Fraser was careful to note that the study could not evaluate specific reasons for the health advantages observed among Adventists. While past studies have suggested that following a vegetarian diet may play an important role, more research is needed to evaluate the specific reasons.
"The findings in this report comparing all Adventists — vegetarians and nonvegetarians — to average Americans are largely as expected, and strongly suggest that these health advantages may be available to all Americans who choose similar diets, in addition of course to other well-known prudent lifestyle choices such as regular physical activity, avoiding smoking, and care with body weight," he said in the press release.
Approached for outside comment, Fang Fang Zhang, MD, PhD, an associate professor at the Friedman School of Nutrition Science and Policy at Tufts University in Boston, Massachusetts, said the findings are mainly hypothesis-generating and cannot be applied to the larger US population just yet.
"This study did not directly evaluate whether the differences in cancer rates and mortality might be due to healthier lifestyle factors among Seventh Day Adventists. One cannot isolate any single factor based on this study," said Zhang, who was not involved with the study, via email.
While the study has many strengths — including careful analyses and a well-characterized special population, which may provide information that studies carried out in the general population cannot — Zhang believes it is too early to draw conclusions.
"I do not think we can make clinical recommendations based on findings of this study. Future studies are warranted to investigate why [rates of cancer and death were lower among Adventists compared to the general US population]," she concluded.
Details of the Findings
The study was part the Adventist Health Study 2 (AHS-2), which began in 2002 and is evaluating the role of diet and other life factors on the risk of cancer among North American Seventh-Day Adventists. Participants in the AHS-2 study are aged 30 years or older and come from across the US. More than half (60%) of the participants are women and 26% are black.
In the study, researchers compared AHS-2 participants to a nationally representative sample of nonsmokers in the National Longitudinal Mortality Study (NLMS), a substudy of the Surveillance Epidemiology and End Results (SEER) study, which has data from about 30% of the US population. Results were adjusted for age, sex, race, smoking history, education, and location of residence. Average follow-up was 7.8 years.
Overall, results showed lower all-cause mortality for Adventists compared with individuals in the NLMS, which varied by age. Adventists aged 65 years had 36% lower risk of all-cause mortality (hazard ratio [HR], 0.67; 95% confidence interval [CI], 0.64 - 0.69) and Adventists aged 85 years had 22% lower risk (HR, 0.78; 95% CI, 0.75 - 0.81).
Adventists also had 30% lower incidence of all types of cancers (HR, 0.70; P < .0001), particularly cancers of the breast (HR, 0.70; P < .0001), colorectum (HR, 0.84; P = .035), rectum (HR, 0.50; P < .0001), and lungs (HR, 0.70; P = .002).
Cancer incidence varied by type of cancer, but in general was significantly lower for Adventists, with the exception of cancers of the colon (HR, 1.01; 95% CI, 0.84 - 1.22; P =.96), prostate (overall: HR, 0.91; 95% CI 0.81 - 1.03; P = .12; Black: HR, 1.11; 95% CI 0.84 - 1.47; P =.47), and endometrium (HR 0.91; 95% CI 0.71 - 1.16; P = .45).
Separate analyses that compared black Adventists to blacks in the NLMS showed 36% lower risk of all-cause mortality and 22% lower incidence of all cancers in favor of black Adventists (HR, 0.64; 95% CI, 0.59 - 0.69; P < .0001; and HR, 0.78; 95% CI, 0.68 - 0.88; P < .0002, respectively).
Adventists also had longer lifespans than individuals in the NLMS, both overall and for blacks. They also had lower rates of cancer mortality, especially for cancers related to premature deaths (overall: HR, 0.90; P < .0001; Black: HR, 0.83; P = .0007).
Separate analyses that controlled for a healthy volunteer effect — which could bias results if healthier people are more likely to participate in a study than unhealthy people — showed similar results.
The Adventist Health Study 2 was supported by the National Cancer Institute and the World Cancer Research Fund (UK). The National Longitudinal Mortality Study was supported by the National Institutes of Health, the Centers for Disease Control and Prevention, and the US Census Bureau.
Loma Linda University Health is a Seventh-Day Adventist institution. Coauthors Gary Fraser, Andrew Mashchak, and Michael Orlich are members of the Seventh-day Adventist church. Orlich and Fraser are employees of Loma Linda University Health's Faculty Medical Group. Zhang has disclosed no relevant financial relationships.
Cancer. Published online November 25, 2019. Abstract
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Cite this: Longer Life, Lower Rates of Cancer in US Seventh-Day Adventists - Medscape - Nov 26, 2019.