Vegan Diets and Longevity: What Existing Science Actually Says

Vegan Diets and Longevity: What Existing Science Actually Says

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There is no question whether or not our current meat production complex is inhumane, unsanitary, or bad for the environment. Almost all chickens (99.9%), turkeys (99.8%), and most cows (70.4%) eaten in the United States are raised on factory farms. There are horrific consequences to this practice. 

For example, the EPA estimates agriculture is the biggest contaminator of rivers and streams, to the point where feedlots, crop production, and manure runoff have led almost half (46%) of the U.S.’s rivers to be “in poor biological condition.” 

Scientific American also explains, “TDM-approved feed containing antibiotics [are] a necessity if [factory farm animals] were to stay healthy in their crowded, manure-gilded home. Antibiotics also help farm animals grow faster on less food, so their use has long been a staple of industrial farming.” Many scientists worry that antibiotics used at such a scale on farms create unstoppable, drug-resistant bacteria that can transfer to humans; think inconveniences like nose infections or UTIs turned deadly because of the lack of antibiotics available to treat them. 

And that doesn’t even count the animal suffering that these farms produce. From teeth clipping piglets to hock-burned chickens, there’s no shortage of animal cruelty found on these farms. There are very, very good ethical reasons to boycott them altogether. Removing all animal products from one’s daily life is the best way to ensure you’re not supporting these kinds of farms. That means becoming a vegan. 

But what does eating vegan do for our health and longevity? Could veganism, in addition to being an ethical choice, help us live longer too? 

Scientists like nutritional biochemist Dr. T. Colin Campbell, physician Dr. Michael Greger, and physician Dr. Caldwell Esselstyn would like to argue that that’s the case. Let’s take a look.

What is veganism?

Unlike the Mediterranean, intermittent fasting, and other longevity diets we’ve covered on our site, veganism isn’t about which foods to seek out, when to eat, nor how much—it’s about what to avoid. To be a vegan, you simply need to avoid animal products

That means:

  • No red meat, like beef, pork, and lamb
  • No poultry, like chicken and turkey
  • No fish or shellfish, like salmon or crab
  • No eggs, like caviar or chicken eggs
  • No dairy products, like milk, cheese, or butter
  • No animal by-products, like honey or royal jelly
  • No animal-derived additives, like gelatin, whey, or L-cysteine

Veganism eliminates many common household foods like mayonnaise (made with egg yolks), Worcestershire sauce (made with anchovies), and many candies (often made with gelatin, carmine, and shellac). 

What about whole foods, plant-based diets?

“Vegan” is often interchanged with the term “whole foods, plant-based diet,” or “plant-based” for short. 

Whole food, plant-based diets are diets based on plants—whole grains, fruits, vegetables, and legumes make up most of what plant-based dieters eat. The “whole food” part of the diet means prioritizing minimally processed or refined ingredients. In general, people who eat plant-based avoid, but are not necessarily prohibited from eating animal-derived products. 

For example, vegans may eat olive oil, but whole foods, plant-based dieters might not because the oil is processed. And some plant-based eaters might indulge in an egg every once in a while—vegans wouldn’t consider doing so a part of their lifestyle.  

Distinguishing between the two diets is important as we break into the research. “Plant-based” is often used as a shorthand for vegan. 

For the purpose of this article, we’re only looking at vegans. Some whole foods, plant-based dieters may fall into this category, but not all.

Note of caution
As a warning, I’m not a scientist, this is not a comprehensive meta-analysis or scientific review. I tried to present the studies I found most representative, with a bias towards the most recent ones, but I’m sure I missed a ton. Please note that I omitted The China Study, which was a little too problematic to cite while doing this writeup.

Vegan diets for longevity

Between 2015 and 2020, PubMed recorded over 150 studies with “vegan” in the title. As a point of contrast, between 2009 and 2014, only 47 studies with the same search parameters were published. Interest in the diet is gaining scientific attention. It’s worth noting that vegans have a 15% reduced incidence of cancer.

As I filtered through studies, I discovered that it was tough to control for what vegans were eating, versus what they weren’t. I also found that many studies were observational. As mentioned before in our article “Why Is Nutrition So Damned Confusing?,” it’s tough to establish causation with such studies acting as the underpinning of research. As I explained in that article, “One can find correlations between cabbage and innie belly buttons, egg rolls and dog ownership, and potato chips and high math scores. The causation/correlation problem is particularly problematic in nutrition research” when relying on observational studies. 

As such, I organized my findings on veganism and longevity by food type: from most to least compelling in terms of health impacts.

Processed meat and longevity

The vegan diet for life extension: no bacon allowed
Bacon: a popular processed meat

The World Health Organization classifies processed meat as a Group 1 carcinogen. Processed meat includes ham, sausage, bacon, pepperoni; they’re meats that have been preserved with salt or smoke, meat that has been cured, and meat treated with chemical preserves. Other Group 1 carcinogens include formaldehyde, tobacco, and UV radiation. Group 1 carcinogens have “enough evidence to conclude that it can cause cancer in humans.”

The support for this conclusion is substantial. For example, a study featuring almost a half-million participants (448,568) found, “Significant associations with processed meat intake were observed for cardiovascular diseases, cancer, and ‘other causes of death.’’’ Additionally, in another systemic review and meta-analysis of 20 studies, a study published in Circulation found a high correlation between processed meat consumption and diabetes mellitus and coronary heart disease. 

Of all the research I filtered through, I found close to a unanimous consensus that processed red meat should probably be avoided for those interested in increasing one’s life and healthspan (sorry about your bacon, J.P.). 

Unprocessed red meat

Vegans and longevity: no red meat
Steak, a common red meat that vegans avoid for longevity

Red meat (or meat derived from mammals, which is often red before it’s cooked) is considered a Group 2a carcinogen—the group of carcinogens that are “probably” carcinogenic for humans. Other Group 2a carcinogens include anabolic steroids, circadian disruption due to shiftwork, and preservatives like creosote. 

Red meat has been well studied as well. For example, a meta-analysis of nine articles examining 150,328 deaths found that red meat consumption is associated with an increased risk of “total, cardiovascular and cancer mortality.” Another oft-cited Harvard study found that “9.3% of deaths in men and 7.6% in women” could have been prevented in their cohort if they had reduced their red meat intake to a half-serving per day. The same study found that red meat “is associated with an increased risk of total, CVD and cancer mortality.”

Not all research on unprocessed red meat is bad. For example, many studies on red meat have been criticized for conflating unprocessed red meat and processed red meat; when properly controlled for, studies have found that red meat may not necessarily cause diabetes or coronary heart disease. Other studies have suggested that red meat itself may not cause cancer, but how it’s prepared for consumption (you might want to take pan-fried beefsteak off the menu). It may even be beneficial, especially when used to replace carbs when on a low-carb diet.

White meat

“White meat” is shorthand for poultry in nutrition studies—most notably chicken. And boy do Americans love chicken.

Per capita consumption of chicken compared to other meats

Poultry consumption may be associated with increased risks for non-Hodgkin lymphoma, malignant melanoma, and prostate cancer. Otherwise, a majority of the studies that I found on poultry did not correlate with an increase in mortality from the poultry itself

However, the ways in which chicken, specifically, is sourced substantially affected participant outcomes in many related studies. Remember: almost every single chicken eaten in the United States (99.9%) comes from a factory farm. There are concerning consequences. 

For example, arsenic is commonly found in traditional chicken, which has been shown to transfer to regular consumers of chicken. Arsenic consumption can lead to skin lesions and some cancers. Another review of studies looking at antibiotic use on factory farms found that antibiotic resistance transfers to human consumers. While I couldn’t find specific longevity effects on the individual level based on personal consumption, the CDC reports, “more than 2.8 million antibiotic-resistant infections occur in the U.S. each year, and more than 35,000 people die as a result.”

In other words, I didn’t find much research to substantiate swearing off chicken. However, there’s good research to support avoiding factory farmed chicken and processed poultry. 

Fish and life extension

Fish and vegan diets don't go together
Salmon: off the table for vegans

When filtering through nutrition studies, I found that fish, like poultry, is not necessarily harmful to human health on its own. In fact, many studies suggest that fish is quite healthy—regular consumption may reduce cerebrovascular risk, especially in men. And fish is an important part of the Mediterranean Diet.

However, as was also the case with poultry, farming practices itself may make sourcing healthy fish exceptionally difficult. Two problems with eating fish consistently arose in my research: mercury and microplastics. 

According to the WHO website, “Mercury is considered by WHO as one of the top ten chemicals or groups of chemicals of major public health concern.” Large fish—namely shark, swordfish, king mackerel, and tilefish—contain such high levels of mercury that they should never be eaten. Other fish and shellfish, like salmon, shrimp, and tuna, should be eaten in moderation. The University of Michigan has a good roundup of how much of which fish and shellfish is safe to consume weekly. 

As for microplastics, a 2021 study published in Global Chain Biology found that 210 species of “commercial importance” (aka eaten by humans) are ingesting plastic debris. Farmed fish have also been found to have substantial levels of microplastics as well

That said, there isn’t really a scientific consensus or much research into what the consequence is of eating fish contaminated by microplastics. 


No cheese, milk, or butter when eating a vegan diet for longevity
A cheese spread

Seventy-five percent of the world’s population is lactose intolerant. As far as researchers know, humans are the only species that consumes milk (particularly cow’s milk) directly from other animals or beyond infancy. 

Is that intrinsically bad? Not necessarily, but it does lead some vegans to raise an eyebrow. 

Dairy is most often linked with breast cancer. For example, a recent study published in the International Journal of Epidemiology found that a cup of milk consumption per day may increase breast cancer rates up to 50% in women. Some studies have also found that prostate cancer correlates with milk consumption as well

A 2017 cohort analysis tells a more nuanced story about dairy, however. The findings were published in the American Journal of Epidemiology

We noted 11% lower all-cause mortality and 16% lower CVD mortality risk with high yogurt intake. Cheese intake was associated with 16% lower all-cause mortality and 26% lower CVD mortality risk. Higher intake of high-fat dairy food and milk was not associated with all-cause or CVD mortality. Neither intake of individual dairy products nor intake of total dairy products was significantly associated with overall cancer mortality. High consumption of dairy products, especially yogurt and cheese, may reduce the risk of overall and CVD mortality. 

In other words, researchers found that certain kinds of dairy may actually be protective for cardiovascular disease. 


Eggs are off limits for vegans

As mentioned in our roundup article about the blue zone diet for longevity, the jury is out on eggs. 

In a 2021 longitudinal analysis of Italian adults, eating no eggs and eating more than four eggs in a week increased all-cause and cancer-specific mortality. Cholesterol—as indicated in a separate 2021 cohort study—may be the cause; while egg consumption again correlated with all-cause mortality, researchers also found that “egg white/substitute consumers had lower all-cause mortality and mortality from stroke, cancer, respiratory disease, and Alzheimer disease compared with non-consumers.” The researchers add, “Hypothetically, replacing half a whole egg with equivalent amounts of egg whites/substitutes, poultry, fish, dairy products, or nuts/legumes was related to lower all-cause, CVD, cancer, and respiratory disease mortality.”

Evidence contrary to veganism for life extension

Vegans don’t necessarily live longer than non-vegans; there is “no difference in all-cause mortality between vegetarians and non-vegetarians,” though plant-based dieters have been shown to have lower all-cause mortality than the general population.

In other words, I didn’t find much compelling evidence that veganism alone necessarily contributes to life extension. Vegans and vegetarians tend to be more active and health conscious, so it’s particularly difficult to untangle which of their behaviors benefit or detract from their overall health. Vegans may also be at greater risk for a stroke

A well-known problem with veganism are nutritional deficiencies, particularly with choline, calcium, B12, zinc, and iron. While more research is needed, women may want to pay particular attention to the effect of avoiding animal products while pregnant; a 2019 review published in Nutrients found that vegan and vegetarian mothers tend to suffer undernutrition and consequential “impaired fetal growth.”

Vegans also frequently struggle with depression and eating disorders, though causality, like with so much of the other research cited in this article, has yet to be established. 

How do I start a vegan diet?

 First off, don’t start any diet intervention without first consulting your doctor, especially if you may have health conditions (like genetic nutrient deficiencies) or comorbidities that could make it dangerous, or if you’re pregnant.  

I wasn’t particularly compelled by the health arguments for veganism. With that said, plant-based diets may be more worth your time.

If you’re interested in a whole foods, plant-based diet, consider starting here: 

  • Invest in five major food categories: fruit, vegetables, tubers, whole grains, and legumes.
  • Lower your meat, dairy, and egg consumption to occasional treats. While there aren’t formal recommendations on how much meat one can have while eating a whole food, plant-based diet, a common recommendation is to think of meat more of like a condiment instead of a main dish.
  • If you do choose to eat meat, be mindful about where you get it from. Look for Certified Humane/Certified Animal Welfare Approved labels on the packaging if you can’t find locally sourced animals fed in a breed-appropriate manner. 
  • Join plant-based communities like r/plantbaseddiet.

Longevity and veganism

As with all other articles on Longevity Advice, I’m open to being wrong. 

Are you a vegan? Is plant-based the way to go for life extension? I’d love to hear about important studies that I’ve missed in my research. Or are you staunchly anti-vegan? Let me know in the comments!


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  5. Deborah

    Two comments: 1. ‘Vegan’ is a western term and definition. It may be interesting to investigate the origin of the term. Many vegetarians will eat eggs, dairy, honey, etc. 2. Instead of looking at the science of how different proteins impact your health and longevity, why not look at the science behind what certain plant-based categories do for your health and longevity (seaweed, legumes, whole-grain, root vegetables, mushrooms, etc). Most studies indicate Americans eat too much protein so part of the impact of a vegetarian diet is the decrease in protein overall and an increase in other dietary categories.

    1. Rachel Burger

      Good points! The reason we chose to cover “vegan” instead of vegetarian, or WFPB, or another variation of low animal product eating is because the definition of all those other diets make it incredibly difficult to control for while going through the literature–for example, are vegetarians who eat two eggs a week healthier than those who eat two a month, or four? And how do they compare to vegans? It’s tough to overlay studies to find trends with so much variability in the diets (we had this same problem when J.P. looked at the Meditteranean diet for longevity too). Because nutrition is such a nascent field, it’s far easier to examine the extremes than moderation in any direction. I appreciate your point though! And while Longevity Advice doesn’t take a particular position on any specific diet as of now, I personally believe the Carnivore Diet is probably headed in the wrong direction.

      It’s worth noting that the kind of protein matters too–not all protein is created equal) I don’t believe that there’s consensus on optimal protein intake beyond the standard .8g per kg, and that most older adults (over 55) really don’t get enough to ward off sarcopenia. I know that this is a point of contention between plant-based/non plant-based dieticians and physicians.

      As for plant categories, that’s a good recommendation. We have something in the works that’s along those lines for early next month. I will caution, however, that food-by-food reviews tend to not be based on studies, but on the micronutrients of each food evaluated. Michael Pollan famously cautioned against doing this. I love this clip of his:

      No single event marked the shift from eating food to eating nutrients, though in retrospect a little-noticed political dust-up in Washington in 1977 seems to have helped propel American food culture down this dimly lighted path. Responding to an alarming increase in chronic diseases linked to diet — including heart disease, cancer and diabetes — a Senate Select Committee on Nutrition, headed by George McGovern, held hearings on the problem and prepared what by all rights should have been an uncontroversial document called ”Dietary Goals for the United States.” The committee learned that while rates of coronary heart disease had soared in America since World War II, other cultures that consumed traditional diets based largely on plants had strikingly low rates of chronic disease. Epidemiologists also had observed that in America during the war years, when meat and dairy products were strictly rationed, the rate of heart disease temporarily plummeted.

      Naively putting two and two together, the committee drafted a straightforward set of dietary guidelines calling on Americans to cut down on red meat and dairy products. Within weeks a firestorm, emanating from the red-meat and dairy industries, engulfed the committee, and Senator McGovern (who had a great many cattle ranchers among his South Dakota constituents) was forced to beat a retreat. The committee’s recommendations were hastily rewritten. Plain talk about food — the committee had advised Americans to actually ”reduce consumption of meat” — was replaced by artful compromise: ”Choose meats, poultry and fish that will reduce saturated-fat intake.”

      …Organized nutrient by nutrient in a way guaranteed to offend no food group, it codified the official new dietary language. Industry and media followed suit, and terms like polyunsaturated, cholesterol, monounsaturated, carbohydrate, fiber, polyphenols, amino acids and carotenes soon colonized much of the cultural space previously occupied by the tangible substance formerly known as food. The Age of Nutritionism had arrived.

      In other words, we can certainly go through each plant food group, but it’s underpinned by this kind of problematic research (you can see this when searching for specific foods on Healthline, for example). There are no randomized controlled trials of cabbage. And for that matter, who would fund them? So all we can do is look at these foods’ micronutrient composition, which food scientists have done to create the entire processed “health” food industry–not something we endorse either.

      Good points all around!

      1. HB

        Rachel, it was great to see you say that not all protein is created equal…but then you didn’t elaborate and next sentence is back to optimal amount of(not type of) protein, while Dr. Michael Greger’s website NutritionFacts, and youtube channel(which also have covered the McGovern report and the political attacks on it, in one video; and “The Great Protein Fiasco” in another video or two) have posted about concrete research, various ways in which plant protein is healthier/animal protein more harmful, which would address the comment made [“Most studies indicate Americans eat too much protein so part of the impact of a vegetarian diet is the decrease in protein overall and an increase in other dietary categories”]

        Those videos by Dr. Greger (not the same as the Great Protein Fiasco;I can’t recall their titles) are worth finding and watching. In fact, may I suggest finding and watching at least 10 or more videos on his NutritionFactsDOTorg on protein?Also longevity?You seem to mean well, I expected an article full of anti-vegan excuses, but the case is much stronger, and I’m tired right now…including of my browser freezing up on this comment form, unfreezing, refreezing..(firefox fwiw).

        But don’t just watch the videos, on his dotOrg site, there’s a tab, not just Transcript tab, but another tab called Sources Cited or a similar name..he links to every study he uses. Also worthwhile, videos on how anti-reg research is doctored, by asking the wrong question to deliberately not show an effect (you indirectly alluded to one type; the analog of comparing smoking 15 to smoking 12 cigs a day to “prove” cigs are okay or that quitting doesn’t help; but there’s other types of tricks used]

        In another comment you said you didn’t know of Healthspan…not 100% if Dr. G covered it, he might have,worth a look — but I’d add even more basic than healthspan (some way to define a Metric for Number of Years while Healthy) is just (as you alluded to) less cancer(pretty sure I saw more than 15% difference in at least some studies; see Dr. G vids on cancer),and cardivascular but also even other disease — if that’s not healthier, having lower chance of the biggest killers, I don’t know what is…so those are worth looking up.

        I’ve been vegan since mid 1990s,for health reasons mostly, not until 5 years into it that the ethical (which I always thought of as a factor but hadn’t research how bad the horror is) …only around the turn of the century did ethics become a bigger role..we’re torturing them to death, almost impossible to humnely kill…and even if it was done with zero suffering?Then I urge you to find (one Australian site has a nice chart, I can find URL if you wish)comparing natural lifespan by species, versus average age killed. We don’t kill them at 1/2 or 1/3 their lifespan, or 1/4, or 1/5…it’s days to weeks to months old, and a tiny fraction of their even if zero suffering(which it’s not),how ethical?And say it out loud with me: “We’re literally eating children and/or babies” is what those numbers literally show…

        Actually I met Greger at Cornell before he was an M.D. and don’t think he walks on water (he seems to love any research that says caffeine is a-ok or even cool,opposite not so much 😉 but he does have a team of researchers reading every English language nutrition review and that Sources Cited tab and all the myths especially on protein, and on so much else.Feel free to email me for refs etc..your heart seems in the right place to find out more…What will you do when you find more info that you know for certain the public will find very hard to handle?Maybe a little humor and other ways to keep people from shutting down when presented with Inconvenient Truths, and your writing skills are far better than mine for that,so please don’t watch just 10 vids by Dr. Greger, but 20 or 30 or 40 (I’m not like others who’ve watched them all, but over last 10 years? certainly 10 or 20 per year, times 10 years, equals…I’ve watched that many) and so much that isn’t known, including things to add, not in this article, so with that I wish you well..peace..

        1. Rachel Burger

          Hi HB! Thank you for taking the time to write such a long, detailed response. I always love seeing people who are passionate about life extension interventions :).

          I didn’t get into the protein debate because my colleague, J.P. Medved, is writing a whole article on it that we’ll publish in the next few weeks. Keep your eye out for it!

          When I was a vegetarian, I was a huge fan of Dr. Greger! I used his Daily Dozen app and personally still use a lot of his recommendations to guide my own food choices. I find his ethic admirable–few doctors get to the level of fame that he enjoys and don’t further monetize. I’ve certainly watched more than 10 of his videos :). I do think he’s chosen a “side” though, when it comes to nutrition. I think it’d be a pretty big shock to his fans if he started to advocate for a ketogenic diet, for example, based on new research. Again, that’s not to say that his interpretation of research is bad. However, he is biased. I’d just be aware as you read through his material. 

          And remember, nutrition is really, really hard to research in a controlled environment. As I noted in another piece (Why is Nutrition So Damned Confusing):

          The trouble with observational studies is that they don’t have the same level of precision as randomized controlled trials. For example, in many, if not most nutritional studies, participants are asked to track all of their food inputs throughout the day—something humans are particularly bad at doing to begin with. And researchers can’t control for everything. One can easily find correlations between meat-eating and cancer diagnoses based on these studies. One can also find correlations between cabbage and innie belly buttons, egg rolls and dog ownership, and potato chips and high math scores. The causation/correlation problem is particularly problematic in nutrition research. 

          You’re right about the 15% rate of lower cancer incidence in vegans, as I note in this article. 🙂 

          As for animal welfare, that’s something that I care deeply about on a personal level. I do believe that sustainable and ethical farming practices are a part of the life extension discussion. And that said, I do find your dedication to the ethical treatment of animals admirable. Since veganism has been working so well for you for so long, I see no reason to stop. No one knows what the perfect diet looks like, and I’m a big believer that your body is much more intuitive than we give it credit for. If you’re happy as a vegan, eat vegan!

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