Studies show that people who dont eat meat may be less likely to live to 100, but this result largely depends on age, weight, and diet.
A recent study suggests that people who avoid meat are less likely to live to 100 years old compared to meat-eaters. However, before viewing this as a 'warning sign' for plant-based diets, these results need to be examined more closely.
Researchers tracked more than 5,000 Chinese people aged 80 and older participating in China's Longevity and Health Longevity Study – a nationally representative survey that began in 1998. By 2018, data showed that those who did not eat meat had a lower rate of reaching the age of 100 compared to those who still ate meat.
At first glance, this finding seems to contradict much of the previous research, which has shown that plant-based diets are beneficial to health. Vegetarian patterns are often associated with lower risks for cardiovascular disease, stroke, type 2 diabetes, and obesity, due to their high fiber content and low saturated fat.
So why did this study yield different results? The answer lies in several key factors that need to be considered before drawing general conclusions about the link between diet and longevity.
Nutritional needs change significantly with age.
This study focuses on individuals aged 80 and older – a group with very different nutritional needs compared to younger people. As people age, their bodies undergo many physiological changes: energy expenditure decreases, muscle mass and bone density decline, and appetite diminishes. These factors increase the risk of malnutrition and debilitation.
Much of the evidence for the health benefits of a meat-free diet comes from studies on young and middle-aged adults, rather than on the more vulnerable older age group. Some studies even suggest that older adults who don't eat meat have a higher risk of fractures due to lower protein and calcium intake.
In later life, nutritional priorities also change. Instead of focusing on long-term chronic disease prevention, the main goals are maintaining muscle mass, avoiding weight loss, and ensuring each meal is nutrient-rich. Therefore, the study's results may reflect the nutritional challenges of very old age, rather than necessarily suggesting that a plant-based diet is 'unhealthy'. This does not negate the proven health benefits of this diet for younger, healthier individuals.
Body weight is a key factor.
A crucial detail in the study is that the risk of not reaching 100 years of age in the meat-free group only appeared in those who were underweight. This association did not exist in older adults with normal weight.
Being underweight in older adults has long been associated with a higher risk of debilitation and mortality. Therefore, body weight appears to play a significant role in explaining the study's findings.
Furthermore, this is an observational study, meaning it only shows an association, not a cause-and-effect relationship. The fact that two factors are present together does not mean that one causes the other. This result is also consistent with the concept of the 'obesity paradox' in older adults, where slightly higher weight is sometimes associated with better survival in later life.
Notably, the risk of reduced lifespan did not appear in those who did not eat meat but still consumed fish, dairy, or eggs. These foods provide essential nutrients for maintaining muscle and bone, including high-quality protein, vitamin B12, calcium, and vitamin D. The elderly group following this diet had a similar likelihood of living to 100 years old as those who ate meat. Researchers suggest that incorporating moderate amounts of animal-derived foods may help prevent malnutrition and muscle loss in very old age, compared to a purely plant-based diet.
The significance for healthy aging.
Instead of debating which diet is 'best' for everyone, the key takeaway is that nutrition needs to be adjusted for each stage of life. As we age, energy needs decrease due to a slower metabolism, but the need for certain micronutrients increases.
Older adults still need sufficient protein, vitamin B12, calcium, and vitamin D to maintain muscle mass and prevent weakness. At this stage, preventing malnutrition and weight loss is often more important than preventing chronic diseases in the long term.
A plant-based diet can still be very healthy, but for older adults, it requires careful planning and sometimes micronutrient supplementation to ensure adequate nutrition.
In short, nutritional needs at age 90 are certainly very different from those at age 50. Dietary advice also needs to change throughout life – and that's perfectly normal. What works for you now may need adjusting in old age.