A vegan diet is one of the healthiest dietary patterns available, but it isn’t definitively “the healthiest.” Large studies consistently show that people who eat entirely plant-based have lower rates of heart disease, type 2 diabetes, and certain cancers compared to typical omnivores. Yet other dietary patterns, particularly pescatarian and Mediterranean diets, show similar or sometimes better outcomes for longevity. The answer depends less on the label and more on what you actually put on your plate.
What the Longevity Data Actually Shows
The Adventist Health Study 2, one of the largest and longest-running investigations into diet and lifespan, tracked over 73,000 people and compared five dietary patterns. Vegans had a 15% lower risk of dying from any cause compared to nonvegetarians, but this result just missed the threshold for statistical significance. Pesco-vegetarians (who ate fish but no other meat) actually had the strongest association, with a 19% lower risk of death that did reach significance.
The results split interestingly by sex. Vegan men showed a striking 28% lower risk of dying from any cause and a 55% lower risk of dying from heart disease compared to nonvegetarian men. Vegan women, however, showed no meaningful mortality difference from nonvegetarians. Researchers aren’t entirely sure why, though differences in baseline diet quality and hormonal factors likely play a role.
What this tells you: going vegan offers real protective benefits, especially for heart disease, but it doesn’t hold a clear edge over every other plant-forward eating pattern.
Heart Health and Cholesterol
Cardiovascular protection is where vegan diets shine most consistently. A meta-analysis of randomized trials found that plant-based diets reduced LDL cholesterol (the type that clogs arteries) by about 0.30 mmol/L compared to omnivorous diets. They also lowered total cholesterol and apolipoprotein B, a protein that carries cholesterol into artery walls. These aren’t trivial changes. Sustained LDL reductions in that range translate to meaningfully lower risk of heart attacks and strokes over a lifetime.
The mechanism is straightforward: eliminating animal products removes dietary cholesterol and most saturated fat, while increasing fiber intake from whole grains, legumes, and vegetables. Fiber binds cholesterol in the gut and pulls it out of the body before it reaches the bloodstream.
Blood Sugar and Type 2 Diabetes
For people managing or trying to prevent type 2 diabetes, vegan diets produce some of the most impressive results in clinical trials. In a head-to-head comparison with the standard diet recommended by the American Diabetes Association, a vegan diet dropped HbA1c (a measure of average blood sugar over three months) by 1.23 points compared to just 0.38 points on the conventional plan. That gap is clinically significant.
Even over longer follow-up periods, the advantage held. After 74 weeks, the vegan group maintained an HbA1c reduction of 0.40 points while the conventional group saw essentially no change. Among participants who stuck closely to their assigned diets, the difference was even more pronounced: a 0.9-point drop for vegans versus 0.3 points for the conventional group. Studies also show improvements in insulin sensitivity, meaning the body’s cells become better at responding to insulin and pulling sugar out of the blood.
Gut Health and Digestion
Your gut bacteria change substantially on a plant-heavy diet. Research from the Baltimore Longitudinal Study of Aging found that people eating more plant foods had higher levels of bacterial species that break down complex carbohydrates, including Faecalibacterium prausnitzii, a species strongly linked to reduced gut inflammation. These bacteria ferment fiber into short-chain fatty acids that nourish the cells lining your colon and help regulate immune function throughout the body.
A vegan diet naturally delivers more of the raw material these beneficial bacteria need: fiber from legumes, whole grains, fruits, and vegetables. The average omnivore in Western countries gets about 15 grams of fiber per day. A well-planned vegan diet typically delivers 40 grams or more.
Where Vegan Diets Fall Short
The nutrients that require the most attention on a vegan diet are vitamin B12, iron, zinc, iodine, and calcium. B12 is the most critical concern because plants don’t produce it at all. Studies of vegetarian and vegan populations have found B12 deficiency rates ranging from 25% to 85% in children, with the highest rates among those who have been vegan since birth and don’t supplement. In adults, deficiency develops gradually and can cause irreversible nerve damage if left unaddressed for years. Supplementation or fortified foods are non-negotiable.
Iron and zinc present a subtler problem. Plants contain these minerals, but in forms the body absorbs less efficiently than the versions found in meat. Compounds called phytates, abundant in the legumes and whole grains that form the backbone of a vegan diet, bind to iron and zinc in the gut and reduce absorption further. You can partially counteract this by pairing iron-rich foods with vitamin C (which boosts absorption) and by soaking or sprouting grains and legumes (which breaks down some phytates).
Bone Health Is a Real Concern
A systematic review and meta-analysis covering over 37,000 participants found that vegans had lower bone mineral density at both the hip and spine compared to omnivores, and higher fracture rates. This likely reflects a combination of lower calcium intake, lower vitamin D levels, and potentially lower protein intake in some vegans. Calcium-fortified plant milks, tofu made with calcium sulfate, leafy greens like kale and bok choy, and vitamin D supplementation can close most of this gap, but it takes deliberate planning.
Not All Vegan Diets Are Equal
This is the single most important point the vegan-versus-omnivore debate tends to miss. A diet of refined grain pasta, sugary cereal, chips, and processed vegan burgers is technically vegan but bears little resemblance to the whole-food plant-based diets studied in clinical trials. Research consistently shows that unprocessed and minimally processed plant foods drive the health benefits. Ultra-processed plant foods, while still possibly offering better cardiometabolic outcomes than their animal-based counterparts, don’t deliver the same protection as whole foods.
The practical takeaway: a vegan diet built around vegetables, fruits, legumes, whole grains, nuts, and seeds is genuinely one of the healthiest ways to eat. A vegan diet built around convenience products and refined carbohydrates is not. The same principle applies to omnivorous diets. A Mediterranean pattern rich in vegetables, olive oil, fish, and whole grains performs nearly as well (and possibly better for bone health and certain nutrient needs) as a well-planned vegan diet.
How Vegan Compares to Other Healthy Diets
If you’re choosing between a vegan diet and another well-planned dietary pattern, the honest answer is that the differences are smaller than most advocates on either side suggest. Vegan diets have a slight edge for cholesterol reduction and blood sugar management. Pescatarian diets show the strongest longevity signal in the Adventist data, likely because fish provides omega-3 fatty acids, vitamin D, and B12 without the cardiovascular risks associated with red and processed meat. Mediterranean diets offer similar cardiovascular protection with fewer nutrient gaps to manage.
What all three patterns share matters more than what separates them: abundant vegetables, fruits, legumes, whole grains, nuts, and minimal ultra-processed food. If you thrive on a vegan diet and supplement appropriately, you’re eating one of the healthiest diets studied. If you prefer to include some fish or dairy, the evidence doesn’t suggest you’re meaningfully worse off. The biggest health gains come from moving away from a standard Western diet heavy in processed meat, refined grains, and added sugar, not from debating whether the last 5% of your calories should come from plants or animals.