Observational study finds non-meat eaters less likely to reach centenarian status — Evidence Review

A new study suggests that among adults over 80, being underweight and not eating meat is linked to lower odds of reaching 100, but diet quality and maintaining a healthy weight appear more important for longevity than meat consumption alone. Most large studies support the health benefits of plant-based diets in younger populations, while evidence in the very old is more mixed; see more details in the original study source.

• The new findings echo related research showing the importance of adequate protein and nutrient intake for the very old, and that underweight status is a risk factor for mortality in this group, regardless of diet type 5 10.
• While several large cohort and modeling studies associate lower meat intake and higher plant food consumption with longer life expectancy and lower disease risk, these benefits are most pronounced before age 80 and may diminish or reverse in the oldest age groups 2 4.
• Other studies highlight that dietary diversity and sufficient intake of protein-rich foods—including meat, fish, eggs, and beans—are associated with reduced mortality among those aged 80 and older, supporting the idea that nutritional adequacy becomes increasingly critical with age 5.

Study Overview and Key Findings

Interest in how dietary patterns affect longevity has grown as more people reach advanced ages worldwide. The current study is notable for focusing on adults aged 80 and above, a group whose nutritional needs and health risks differ from those of younger adults. Unlike most research on vegetarianism and health, which centers on middle-aged populations, this study addresses the less-understood challenges of maintaining health and preventing frailty in very old age. The findings emphasize that, for this demographic, preventing undernutrition and maintaining a healthy body weight may take precedence over the long-term benefits observed with plant-based diets in younger groups.

Property	Value
Study Year	2025
Journal Name	The American Journal of Clinical Nutrition
Authors	Yaqi Li, Kaiyue Wang, Yuebin Lv, Guliyeerke Jigeer, Yilun Huang, Xiuhua Shen, Xiaoming Shi, Xiang Gao
Population	Adults aged 80 and older
Sample Size	n=5000
Methods	Observational Study
Outcome	Likelihood of reaching centenarian status
Results	Non-meat eaters were less likely to reach 100, especially if underweight.

Literature Review: Related Studies

To contextualize these findings, we searched the Consensus paper database, which contains over 200 million research papers. The following search queries were used to identify relevant studies:

1. meat consumption longevity comparison
2. non-meat eaters centenarian prevalence
3. underweight diet aging outcomes

Topic	Key Findings
How does meat consumption relate to mortality and longevity?	- High processed meat intake is associated with increased mortality from cardiovascular diseases and cancer, while poultry and fish are not linked to higher mortality 1 3. - Very low meat intake is generally protective in adults under 80, but this effect diminishes or disappears in the oldest age groups 2.
What role does body weight and undernutrition play in aging outcomes?	- Underweight status in older adults is strongly linked to higher mortality, frailty, and poor quality of life, while obesity may have a nuanced or even protective effect in some older populations 7 9 10 11. - Older adults are at increased risk for unintentional weight loss and undernutrition, which can outweigh the risks associated with moderate overweight status in very late life 8 10.
Does dietary diversity and protein intake influence longevity in the very old?	- Greater dietary diversity and frequent consumption of protein-rich foods (including meat, fish, eggs, and beans) are associated with lower mortality and higher likelihood of reaching very old age 5 6. - In some centenarian populations, being a light eater or vegetarian is common, but adequate protein intake (from plant or animal sources) remains important 5 6.
How do plant-based and optimal diets impact lifespan across ages?	- Shifting to an optimized plant-rich diet can substantially increase life expectancy when initiated earlier in life, but gains are more modest when changes are made after age 80 4. - The health benefits of vegetarian or near-vegetarian diets are most robust before the ninth decade, with less clear impact on longevity in the oldest old 2 4.

How does meat consumption relate to mortality and longevity?

Most large-scale cohort studies in younger and middle-aged adults find that high processed and red meat consumption is linked with increased mortality, especially from cardiovascular disease and cancer, while poultry and fish intake does not show this association 1 3. Systematic reviews suggest that very low meat intake is connected to longer life, but this protective effect is less evident in those over 80 2. The new study’s finding—that non-meat eaters over 80 had lower odds of reaching 100, especially if underweight—appears to contrast with the benefits seen in younger groups.

• High processed meat intake consistently predicts higher all-cause and cause-specific mortality in adults, while poultry and fish do not 1 3.
• Adults with very low meat consumption (less than weekly) tend to live longer, but this advantage is not seen as clearly after the ninth decade 2.
• The protective effect of plant-based diets may diminish with advanced age, possibly due to increased risk of undernutrition 2.
• The new findings highlight the need to individualize dietary advice for the oldest old rather than generalize from studies in younger adults 2 3.

What role does body weight and undernutrition play in aging outcomes?

A consistent theme in the literature is that underweight status in older adults is a strong risk factor for mortality, frailty, and reduced quality of life 9 10 11. Unlike in younger adults, where overweight and obesity are major health risks, moderate excess weight may be neutral or even beneficial for survival in the elderly—a phenomenon sometimes called the “obesity paradox” 7 11. The increased vulnerability to malnutrition, involuntary weight loss, and muscle wasting in late life may make adequate caloric and protein intake more critical than strict dietary restriction.

• Underweight in later life predicts higher mortality and poor health outcomes, regardless of dietary pattern 9 10.
• Older adults often have impaired appetite regulation, increasing the risk of unintentional weight loss 8.
• Successful aging in older adults is more closely linked to avoidance of undernutrition than to avoidance of overweight 11.
• The new study’s observation—that being underweight and not eating meat is associated with lower odds of reaching 100—aligns with these findings 10 11.

Does dietary diversity and protein intake influence longevity in the very old?

Studies indicate that dietary diversity and frequent intake of protein-rich foods, whether animal or plant-based, are associated with lower mortality in those over 80 5. In some populations of centenarians, vegetarianism is common, but these individuals often consume adequate protein through other means (such as beans and eggs) and may have unique lifestyle factors 6. Sufficient protein intake is important for preserving muscle mass and function in the oldest old.

• Higher dietary diversity scores predict lower mortality among people aged 80 and above 5.
• Regular consumption of protein-rich foods (meat, fish, eggs, beans) supports longevity in advanced age 5.
• Centenarians in some regions are more likely to be light eaters or vegetarians, but adequate nutrition is still essential 6.
• The apparent disadvantage for non-meat eaters in the new study was mitigated when fish, eggs, or dairy were included in the diet, supporting the importance of protein adequacy 5 6.

How do plant-based and optimal diets impact lifespan across ages?

Meta-analyses and modeling studies show that shifting to an optimized plant-rich diet (high in legumes, whole grains, nuts, fish, and low in red/processed meat) can increase life expectancy significantly—but these gains are greatest when dietary changes are made earlier in life 4. The benefits are smaller after age 80, when preventing undernutrition becomes more important than long-term risk reduction 2 4.

• Adoption of optimal diets can add a decade or more to life expectancy if started in early adulthood; the benefit drops to a few years when changes begin after age 80 4.
• The protective effects of vegetarian or flexitarian diets are less evident in the oldest old, possibly due to increased risk of protein or micronutrient deficiency 2 4.
• The new study’s findings fit with this evidence, suggesting that strict meat avoidance in advanced age may not be optimal without careful nutritional planning 2 4.
• These results support individualized dietary recommendations based on age and health status 4.

Future Research Questions

While this new study adds important insights about diet and aging, further research is needed to clarify optimal dietary patterns for the oldest old, address limitations of observational studies, and explore how individual factors like health status and cultural context modify these relationships.

Research Question	Relevance
How does protein source (animal vs plant) affect frailty and mortality in adults over 80?	Understanding whether plant-based proteins can match animal sources in preventing muscle loss and frailty is crucial for dietary guidance in this group 5 10.
What is the impact of dietary diversity on longevity among centenarians across different cultures?	Cultural dietary patterns may influence the observed benefits of dietary diversity and longevity; cross-cultural studies could clarify universal versus population-specific effects 5 6.
Can supplementation of key nutrients (vitamin B12, calcium, vitamin D) offset the risks of strict plant-based diets in the very old?	Many older adults risk deficiencies on plant-based diets; intervention trials are needed to determine if supplementation can safely support vegetarian and vegan diets in this age group 2 4 10.
How do weight changes (unintentional loss or gain) influence survival and function in the oldest old?	Unintentional weight loss is a strong predictor of poor outcomes in late life, but the long-term effects of weight changes and the optimal weight range for survival and function remain unclear 8 9 10.
What are the effects of combining different animal-source foods (fish, eggs, dairy) on longevity in older adults?	The new study suggests that including fish, eggs, or dairy may mitigate risks seen with strict meat avoidance in the very old; further research could inform optimal combinations of animal-source foods for healthy aging 5.