Vegan diets may not always be associated with longer life in old age, according to a new study by Chinese researchers that found vegans were less likely than omnivores to live to 100.

The study, published Dec. 12 in The American Journal of Clinical Nutrition, analyzed data from more than 5,200 Chinese adults aged 80 and older enrolled in the Chinese Longitudinal Healthy Longevity Survey between 1998 and 2018. 

The findings come as China faces rapid population aging, with the age bracket of those 80 or over growing the fastest of all old age groups. In 2017, just 1.8% of the population was aged 80 or above. But by 2050, it is projected that that number could grow to 8%.

Previous studies have correlated vegetarianism with decreased risks of obesity and heart disease, but few have examined how diets that limit or exclude meat relate specifically to longevity among the oldest adults. 

To assess that relationship, the researchers compared participants who lived to at least 100 with those who had died before reaching that age. Dates of death were verified through family members, doctors, or neighborhood committees. They also assessed diet, BMI, and lifestyle factors using questionnaires.

Participants were grouped by dietary patterns: vegans, pesco-vegetarians (who eat fish), ovo-lacto vegetarians (who eat eggs and dairy), and omnivores. Vegetarians — including vegans, pesco- and ovo-lacto vegetarians — as a group were found to be less likely to live to 100 than omnivores. But when researchers examined the subgroups separately, only vegans showed a statistically significant inverse association with reaching that age. 

Researchers also found that only underweight vegetarians — defined as having a body mass index below 18.5 — were less likely to live to 100 than omnivores. No significant difference was observed between omnivores and vegetarians of normal or higher weight. 

The findings point to a more nuanced relationship between diet and health in advanced age. While vegetarian diets are often high in fiber and low in saturated fat, the authors noted that limited dietary diversity and lower protein intake, both considered important for healthy aging, may pose challenges for older adults who follow restrictive diets.

The authors said their findings underscore the importance of a balanced diet that includes both plant- and animal-based foods for healthy longevity, and called for further research to help shape dietary guidance for people in advanced old age as populations continue to age.

Editor: Marianne Gunnarsson.

(Header image: VCG)