Study finds vegetarians over 80 less likely to reach 100

Researchers followed more than 5,000 adults in China who were age 80 or older and enrolled in the Chinese Longitudinal Healthy Longevity Survey, a nationally representative project that began in 1998. By 2018, participants who did not eat meat were less likely to become centenarians compared with those who consumed meat.

At first glance, this seems to clash with decades of research linking vegetarian and plant based diets to better health. Such eating patterns have repeatedly been associated with lower risks of heart disease and stroke, type 2 diabetes, and obesity. These benefits are often attributed to higher fibre intake and reduced saturated fat consumption.

Before drawing conclusions, it is important to understand who was studied and how aging changes the body's nutritional needs.

How Aging Changes Nutrition Needs

The study focused exclusively on adults 80 and older, a group with very different dietary requirements than younger adults. As people age, the body goes through significant physiological changes. Energy expenditure decreases, and losses in muscle mass, bone density, and appetite are common. Together, these changes increase the risk of malnutrition and frailty.

Most evidence for the health benefits of diets that exclude meat comes from studies of younger adults rather than frail older populations. Some research suggests older non-meat eaters face a higher risk of fractures due to lower calcium and protein intake.

In later life, nutritional priorities shift. Rather than focusing on preventing long-term diseases, the goal becomes maintaining muscle mass, preventing weight loss and ensuring every mouthful delivers plenty of nutrients.

The study's findings may, therefore, reflect the nutritional challenges of advanced age, rather than any inherent problems with plant-based diets. Crucially, this doesn't diminish the well-established health benefits of these diets for younger and healthier adults.

Body Weight and the Underweight Risk

Here's a crucial detail: the lower likelihood of reaching 100 among non-meat eaters was only observed in underweight participants. No such association was found in older adults of healthy weight.

Being underweight in older age is already strongly linked with increased risks of frailty and death. Body weight therefore appears to be a key factor in explaining these findings.

It's also worth remembering that this was an observational study, meaning it shows associations rather than cause and effect. Just because two things occur together doesn't mean one causes the other.

The findings also align with the so-called "obesity paradox" in ageing, where a slightly higher body weight is often linked to better survival in later life.

Role of Protein and Animal Source Nutrients

Notably, the reduced likelihood of reaching 100 observed among non-meat eaters was not evident in those who included fish, dairy or eggs in their diets. These foods provide nutrients that are essential for maintaining muscle and bone health, including high-quality protein, vitamin B12, calcium and vitamin D.

Older adults following these diets were just as likely to live to 100 as meat eaters. The researchers suggested that including modest amounts of animal-source foods may help prevent undernutrition and loss of lean muscle mass in very old age, compared with strictly plant-based diets.

What This Means for Healthy Aging

The broader takeaway is not that one diet is universally superior. Instead, nutrition should match a person's stage of life. Calorie needs tend to decline with age (due to decreased resting energy expenditure), yet certain nutrient requirements actually rise.

Older adults still require adequate protein, vitamin B12, calcium and vitamin D - especially to preserve muscle mass and prevent frailty. In older adulthood, preventing malnutrition and weight loss often becomes more important than long-term chronic disease prevention.

Plant-based diets can still be healthy choices, but they may require careful planning and, in some cases, supplementation to ensure nutritional adequacy, particularly in later life.

Ultimately, what your body needs at 90 may differ substantially from what it needed at 50. Dietary guidance should evolve over time, and adjusting your eating pattern as you age is both expected and appropriate.