In a recent study published in the journal npj Aging, researchers investigated the effects of a vegetarian diet on healthy aging in older Chinese adults.
Their findings suggest that vegetarians may be less likely to achieve healthy aging than omnivores. However, this difference may be due to diet quality, as vegetarians with higher-quality diets did not differ significantly from omnivores in terms of healthy aging.
Background
Vegetarianism, a diet that emphasizes plant-based foods while limiting or eliminating animal products, is becoming increasingly popular. Studies have shown that these diets can reduce the risk of cancer, diabetes, obesity, and cardiovascular disease, especially in middle-aged and younger populations.
They also have benefits such as improved metabolic health. However, less is known about their effects on older adults, who may face nutritional deficiencies because vegetarian diets reduce the intake of essential nutrients such as calcium, iron, vitamin B12, omega-3 fatty acids, and protein.
These deficiencies may lead to muscle loss, fractures, and disability. In addition, the effects of vegetarian diets on health outcomes in older adults, including cognitive function, mental health, and chronic diseases, remain unclear.
As rates of healthy aging remain low, identifying modifiable protective lifestyle factors is critical to promoting health in later life.
About the Study
In this study, researchers used data collected by the China Longitudinal Healthy Longevity Survey to investigate the effects of a vegetarian diet on healthy aging, taking into account diet quality.
This ongoing cohort study includes people aged 60 years and older in 22 provinces in China. Multiple rounds of surveys were conducted between 1998 and 2018 to assess health status, diet, and lifestyle. Ethical approval was obtained for the study, and participants provided informed consent.
The study included 2,888 participants who were initially healthy and had dietary data available for analysis. The researchers defined healthy aging as being able to live to age 80 without experiencing severe chronic diseases, cognitive decline, physical impairment, or poor mental health.
Chronic disease conditions were self-reported, cognitive function was assessed using the Mini-Mental State Examination (MMSE), physical function was measured by activities of daily living (ADL), and mental health was assessed using the Mental Health Index.
Dietary intake was assessed using a simplified food frequency questionnaire. Participants were categorized as vegan, ovo-vegetarian, pescatarian, or omnivore, and dietary stability was examined starting at age 60.
A healthy plant-based diet index (hPDI) (prioritizing whole grains, fruits, and vegetables) and an unhealthy plant-based diet index (uPDI) (including refined grains and sugary beverages) were also calculated. Logistic regression models were used to estimate the association between dietary patterns and healthy aging while adjusting for demographic, lifestyle, and health factors.
Findings
Participants were 72.1 years old on average, and 45% were female. Vegetarians were less likely to be male and more likely to be of Han ethnicity. On average, they had lower income and education levels—factors that may partly explain the observed health disparities. Only 13% of participants followed a vegetarian diet, and less than 3% were vegan.
During the six-year follow-up, 572 participants met criteria for healthy aging. Vegetarians were 35% less likely to achieve healthy aging than omnivores. Among vegetarians, vegans were least likely to achieve healthy aging, 57% less likely than omnivores (OR = 0.43; 95% CI: 0.21–0.89).
Long-term adherence to a vegetarian diet is associated with an increased risk of chronic diseases, physical disability, and cognitive impairment. Vegetarians were almost twice as likely to have physical impairment (OR = 1.95; 95% CI: 1.25–3.04) and cognitive impairment (OR = 2.05; 95% CI: 1.26–3.33) as omnivores. Those who had been omnivores since age 60 were 78% more likely to have healthy aging than those who had been vegetarians.
Similarly, those who were initially vegetarians but later switched to an omnivorous diet also had improved health (although this finding was not statistically significant). Further analyses suggested a dose-response relationship between a strict vegetarian diet and poorer health outcomes (p trend < 0.05).
Diet quality also played a role, as vegetarians with poorer plant-based diets had significantly increased risk of chronic disease (60% [OR = 1.60; 95% CI: 1.17–2.18]), physical disability (95% [OR = 1.95; 95% CI: 1.25–3.04]), and cognitive decline (105% [OR = 2.05; 95% CI: 1.26–3.33]). Sensitivity analyses confirmed the robustness of these findings.
Conclusion
This study investigated the effects of a vegetarian diet on healthy aging in older adults. Findings suggest that maintaining an omnivorous diet from age 60 years onwards is associated with better health aging than adherence to vegetarianism, especially for vegans.
While diet quality influenced outcomes, vegetarians who followed a high-quality diet (hPDI, emphasizing whole foods) did not show a significant disadvantage compared with omnivores. These results suggest that vegetarianism may not universally promote healthy aging and highlight the need for a balanced diet that includes animal-based nutrients.
Previous studies on vegetarianism and health outcomes have been inconsistent and have focused primarily on middle-aged adults. This study adds to the literature by considering overall health in older adults.
Potential disadvantages of a vegetarian diet include deficiencies in protein, vitamin B12, and vitamin D, which may lead to impaired physical and cognitive function. No clear associations were found between a vegetarian diet and mental health outcomes.
The researchers caution that the observed differences may partly reflect socioeconomic factors, as vegetarians in the study tended to have lower income and education levels.
Limitations
Limitations include reliance on self-reported dietary data and potential misclassification. Findings may not be generalizable to populations outside of China. The small sample size of vegans (n = 83) may limit statistical power and robustness of subgroup analyses. Future studies should explore nutritional supplementation and dietary modifications to support healthy aging, ensuring guidelines are tailored to individual needs.
Related topics: