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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.

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 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

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.

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

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. 

Dairy

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

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?

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!

Rachel Burger

By day, I am a problem solver, writer, and the co-founder of Longevity Advice. I’m best known for writing about technology and have been featured in Forbes, The Hill, and TechRepublic. When the batteries are powered down and the suit comes off, I’m an enthusiastic hiker, runner, and Rocket League competitor and enjoy discussing minimalism, Studio Ghibli, and Icelandic sheepdogs.