New Study Challenges the Plant-Based Longevity Myth

In this episode we discuss:

• Overview of a 20-year longevity study
• Why vegetarians and vegans had lower odds of reaching 100
• The risks of nutrient deficiencies in elderly populations
• Protein needs, sarcopenia, and muscle preservation with age
• Key nutrients difficult to obtain from plants alone
• Why one-size-fits-all nutrition advice fails
• Practical guidance for omnivores, vegetarians, and vegans

Show notes:

Hey everybody, Chris Kresser here. Welcome to another episode of Revolution Health Radio. Today I’m discussing a study just published in the American Journal of Clinical Nutrition. It challenges one of the most persistent narratives in nutrition, that plant-based diets are the key to longevity and we should all eliminate or drastically reduce animal foods to live longer, healthier lives.

If you’ve been listening to this podcast, you know I’m not anti-plants. Far from it. Vegetables, fruits, nuts and seeds, and other plant foods should be part of most people’s diets. But I’ve been consistently critical of the idea that eliminating all animal products is optimal for human health. The evidence doesn’t support it, and this study adds another piece to that puzzle. The study followed over 5000 Chinese adults aged 80 and older for up to 20 years to see who lived to be 100. What they found might surprise you, or maybe it won’t if you’ve been paying attention to the science rather than the headlines. When it came to reaching 100, vegetarians and vegans had significantly worse outcomes than omnivores. And the effect was most pronounced in the people who need optimal nutrition most, the underweight elderly.

In this episode, I’m going to explain the results of the study and how those results tie in with previous research on this topic. Let’s dive in.

The Mainstream Narrative About Plant-Based Diets and Longevity

If you’ve been paying attention to mainstream nutrition advice over the past decade, you’ve probably heard some version of the following message: plant-based diets are healthier, plant-based diets are better for the environment, and plant-based diets will help you live longer. Numerous books, documentaries, and studies seem to support this idea, at least on the surface. The Blue Zones, regions of the world where people live the longest, feature diets that are mostly plants with small amounts of animal foods. Studies show that vegetarians and vegans have lower rates of heart disease, diabetes, and cancer. But there’s a critical point that often gets lost. Most of these studies compare plant-based diets to the standard American diet. It’s full of processed foods, refined grains, sugar, industrial seed oils, and factory-farmed animal products. So it shouldn’t surprise us that eating more vegetables and fewer Twinkies is beneficial.

But when you look at well-designed studies comparing well-planned omnivorous diets to vegetarian or vegan diets, the picture changes. Most studies show no difference for vegetarians, and some, including this new one we’re discussing today, show potential harm, especially in vulnerable populations like the elderly. I wrote about this in an article back in 2019 called “What Is the Optimal Human Diet?” If you haven’t read it, I’ll put a link in the show notes. The bottom line is, there’s no one-size-fits-all answer. The optimal diet depends on many factors, including your age, health status, activity level, genetic background, food availability, and personal preferences. But one thing is clear from both evolutionary anthropology and modern nutrition science– humans are omnivores. We evolved eating both plants and animals, and the evidence suggests that for most people, especially as we age, a diet that includes both plant and animal foods is optimal for health and longevity. Which brings us to this new study.

Breaking Down the Chinese Centenarian Study

This study was published in the American Journal of Clinical Nutrition in late 2025. It’s called “Vegetarian diet and likelihood of becoming centenarians in Chinese adults aged 80 years or older: a nested case-control study.” The researchers used data from the Chinese Longitudinal Healthy Longevity Survey, which is one of the largest and most comprehensive studies of older adults in the world. They included over 5000 participants who were all 80 years or older at the start of the study, and they followed them up for 20 years to see who made it to 100. This is a prospective study, meaning they assessed people’s diets at the beginning and then followed them forward in time. This is much better than retrospective studies that rely on people’s memories of what they ate months or years ago. They also had excellent follow up. They were able to track 85 percent of participants, which is really good for a study of this duration in this age group. The participants were classified as either omnivores or vegetarians based on their meat consumption. Omnivores ate meat regularly, while vegetarians rarely or never ate meat. The vegetarians were further divided into three groups, pesco-vegetarians who ate fish, and to be honest, I’m not sure why they’re even called vegetarians if they’re eating fish but whatever, ovo-lacto-vegetarians who ate eggs and dairy but no fish or meat, and vegans who ate no animal products at all. What did they find? After adjusting for age, sex, socioeconomic factors, lifestyle habits, and other variables, they found that vegetarians had a 19 percent lower likelihood of becoming centenarians compared to omnivores. When they looked specifically at the vegan subgroup, the difference was even larger. Vegans were 29 percent less likely to reach 100 years old.

You might be thinking these vegetarians were different in other ways. Maybe they exercised less or smoked more or had other health problems. But remember, the researchers controlled for all of those factors. They adjusted for education, residence (urban versus rural), marital status, smoking, drinking, exercise, body mass index, and chronic conditions like hypertension and diabetes. When they stratified the analysis by body weight, they found that the negative association between vegetarian diets and longevity was primarily driven by underweight individuals, those with a BMI less than 18.5. In this underweight group, vegetarians had a 28 percent lower likelihood of becoming centenarians. But in the normal weight or overweight group, no significant difference existed between vegetarians and omnivores. The people who were already at the highest risk for malnutrition and frailty, the underweight elderly, suffered the most from not eating animal foods.

A major new study challenges the widely held belief that plant-based diets are optimal for longevity. This episode reviews the research, explains its implications for aging adults, and discusses why a balanced omnivorous diet may better support long-term health—especially in older populations. #ChrisKresser #longevity #omnivorediet

Why We Need Both Plants and Animals

As we age, we need more protein, not less. This might be counterintuitive, but it’s well established in the scientific literature. Older adults are at high risk for sarcopenia, which is age-related muscle loss. And sarcopenia is associated with frailty, falls, fractures, loss of independence, and increased mortality. To maintain muscle mass as we age, we need adequate high-quality protein. Animal proteins are complete proteins, meaning they contain all nine essential amino acids in optimal ratios for human needs. They also have higher bioavailability than plant proteins. Your body can use more of the protein from a piece of fish or an egg than from a serving of beans or tofu. Plant proteins, on the other hand, are often incomplete and they’re bound up with antinutrients like phytates and lectins that can interfere with absorption. To get equivalent amounts of usable protein from plants, you often need to eat larger quantities and combine different plant proteins carefully. If you’re a young, healthy person with a robust digestive system and a hearty appetite, and you’re paying close attention, you can probably manage this. But if you’re 85 years old, you’re eating less, and your digestion isn’t what it used to be, every bite counts. You can’t afford to be eating large volumes of lower quality protein sources just to meet your needs.

Animal foods provide a package of nutrients that are either absent from plants or present in forms poorly absorbed by the body. Vitamin B12 is only found naturally in animal foods. Vegetarians who eat eggs and dairy can get some, but vegans need to supplement or eat fortified foods. And vegetarians are often deficient because absorption of B12 from dairy and eggs isn’t great, especially as we age and stomach acid production declines.

Iron presents a similar issue. Yes, plants contain iron, but it’s non-heme ferrous iron, which is much less bioavailable than the heme iron found in meat. The same plants that contain iron also contain phytates that inhibit its absorption. Iron deficiency is common in vegetarians and vegans, and it’s particularly problematic in older adults who may already have low iron stores. Zinc is critical for immune function, which is already compromised in the elderly. Animal foods are the best sources of bioavailable zinc. Plant sources are also bound to phytates, which inhibit absorption. Omega-3 fatty acids present a similar challenge. You can get alpha-linolenic acid from flax and chia seeds, but your body has to convert it to EPA and DHA, the forms your body actually uses. That conversion is inefficient, especially as we age. EPA and DHA from fish and seafood are already in the form your body needs, ready to go. The list goes on: vitamin k2, found in egg yolks, grass-fed dairy, and liver, choline, abundant in egg yolks, carnosine in meat, taurine in seafood and meat, and creatine, also in meat. All of these support healthy aging and are either absent from plants or present in suboptimal forms.

But the equation works both ways. Plants also provide crucial nutrients that are low or absent in animal foods. Vitamin C is the obvious one. Animal foods contain little vitamin C, except for organ meats like liver. You need plant foods to meet your vitamin C requirements in most cases. Fiber is essential for gut health, blood sugar regulation, and satiety, yet animal foods contain zero fiber. You need plants to get adequate fermentable fibers that can support your gut flora. Phytonutrients are compounds like polyphenols, flavonoids, and carotenoids that have beneficial effects on health. They act as antioxidants, reduce inflammation, support detoxification, and positively influence gene expression. These are only found in plants. Potassium and magnesium are crucial for blood pressure regulation, bone health, and countless enzymatic reactions. While animal foods contain some of these minerals, plants, especially vegetables, fruits, and legumes, are much richer sources. If you only eat plants, you’re missing out on critical nutrients like B12, heme iron, zinc, EPA and DHA, and complete proteins in their most bioavailable forms. If you only eat animals, you’re missing out on fiber, vitamin C, phytonutrients, and key minerals like potassium and magnesium.

It’s not just about filling nutritional gaps, though. Synergy exists between plant and animal foods when eaten together. Vitamin C from plants enhances the absorption of non-heme iron from plants. When you eat a salad with steak, you’re getting the highly bioavailable heme iron from the meat, plus you’re improving the absorption of the non-heme iron from the greens. Fat-soluble vitamins like A, D, E, and K need to be consumed with fat for optimal absorption. The vegetables on your plate are much more nutritious when eaten with butter, olive oil, or fat from the meat or fish. The polyphenols from plants and the proteins from animals work together to support muscle protein synthesis and recovery. Some potentially problematic plant compounds such as oxalates and lectins are less harmful when consumed as part of a mixed diet that includes animal foods. The animal protein and minerals help offset some of the antinutrient effects.

In Western countries, we tend to worry about obesity and overweight, but in the elderly, being underweight is a much bigger problem. It’s associated with increased mortality, greater risk of infections, slower wound healing, higher risk of falls and fractures, and loss of independence. When you’re underweight and elderly, you need every nutritional advantage you can get. This is not the time to be experimenting with dietary restrictions. You need the most bioavailable foods possible.

This explains the Chinese study findings. These older adults who eliminated animal foods weren’t just missing out on protein, they were missing out on a whole package of nutrients that are difficult or impossible to obtain from plants alone: B12, heme iron, bioavailable zinc, EPA and DHA, and complete proteins in their optimal ratios. And they lost the synergistic benefits of eating plants and animals together. In elderly people who are already at high risk for malnutrition, who have declining digestive function, who are eating smaller amounts of food, and who may have increased nutrient needs due to inflammation or illness, that’s a recipe for nutritional inadequacy. On the flip side, the omnivores in this study weren’t just eating meat and eggs. Based on traditional Chinese dietary patterns, they were also eating plenty of vegetables and plant foods. They were getting the benefits of both– the bioavailability of animal foods, plus the fiber, vitamin C, folate, and phytonutrients from plant foods. That’s often the sweet spot. That’s the pattern we see in virtually every traditional population that achieved good health and longevity.

The Traditional Diet Pattern

This study reinforces this pattern that we have seen across traditional diets worldwide. Despite popular claims that traditional Asian diets were essentially plant-based, the research tells a different story. Yes, traditional Asian diets included a lot of rice and vegetables, but they also included regular consumption of fish, pork, poultry, eggs, and seafood. In Okinawa, one of the original Blue Zones, pork was consumed regularly. The Okinawans ate the entire pig, including organs. The Mediterranean diet includes fish multiple times per week, along with poultry, eggs, and even some red meat. Even populations that ate relatively little meat still regularly consumed it, along with dairy, eggs, and insects. The idea of populations thriving on a purely plant-based diet is essentially a myth. The common thread across virtually all traditional diets that supported health and longevity is the inclusion of both plants and animals.

Okay, let’s bring this home. What does this study mean for you and your family? If you’re in the 80-plus age group, or caring for aging parents in that age range, don’t assume that a vegetarian or vegan diet is automatically healthier. The evidence suggests it’s unlikely, especially if the person is underweight or at risk of malnutrition. Make sure they’re getting adequate protein. Aim for at least one gram per kilogram of body weight, and possibly more if they’re recovering from illness or injury. Include protein sources at every meal: eggs, fish, poultry, grass-fed meat, and bone broth. Pay attention to weight and muscle mass. Underweight is a much more serious problem than being overweight in this particular age group. If your parent is losing weight or muscle mass, this is, again, not the time to experiment with dietary restrictions. If you’re in your 40s, 50s, or 60s, start building muscle mass now. Sarcopenia doesn’t happen overnight. It’s a gradual process that often begins in your 30s and 40s. By building muscle now and maintaining it through resistance training and adequate protein intake, you’re creating a reserve that will serve you well in later years.

If you’re currently vegetarian or vegan, I’m not necessarily here to tell you that you have to start eating meat, but I do think it’s important to be honest about the challenges and make sure you’re doing it as carefully as possible. If you’re young, healthy, and have no nutrient deficiencies, and you’re willing to pay close attention to your food intake, you might be able to make a vegetarian diet work, though I’d still encourage you to include eggs and dairy if you’re open to it. But if you’re vegan, you must supplement with B12, and you should probably supplement with several other nutrients too, including vitamin D, EPA/DHA omega-3s, iron, zinc, and possibly others, depending on your individual needs. Get regular blood work done. Don’t assume you’re fine just because you feel okay right now. Nutrient deficiencies can be subtle and take years to manifest. Check your B12, vitamin D, iron, ferritin, zinc, and other biomarkers regularly. Be especially careful if you’re pregnant, breastfeeding, elderly, or have any health conditions. These are times when nutrient requirements are higher and the risk of deficiency is greater.

Context matters. There is no one-size-fits-all answer to the question of the optimal diet. A 25-year-old athlete training for a marathon has different needs than an 85-year-old recovering from pneumonia. Someone with an autoimmune disease might need a different approach than someone who’s metabolically healthy. This is why I’m so critical of dogmatic approaches to nutrition, whether that’s veganism, carnivore, keto, or any other restrictive diet that claims to be optimal for everyone. The evidence just doesn’t support that level of certainty. This Chinese study challenges the simplistic narrative that plant-based diets are always healthier and that we should eliminate animal foods to live longer. The reality is more nuanced. We need to stop demonizing entire food groups and start thinking more carefully about the context in which different dietary patterns might be appropriate. For most people, especially as we age, that means a diet rich in plants, but also including regular consumption of animal foods. As I always say, let’s follow the evidence wherever it leads, even when it challenges our preconceptions. That’s what science is all about.

Okay, that’s it for this episode. If you enjoyed it, please leave a review on Apple podcasts or wherever you’re listening. It really helps other people find the show. And if you’re not already subscribed to my newsletter, head over to ChrisKresser.com and sign up. I send out regular updates on the latest research and what it means for your health. Thanks for listening, everybody. Talk to you next time.