A vegetarian diet offers meaningful protection against heart disease and diabetes but does not appear to help you live longer overall. The largest long-term study tracking vegetarians and meat-eaters in Europe found identical all-cause mortality rates between the two groups, with a hazard ratio of exactly 1.00. The real story is more nuanced than a simple yes or no: vegetarian diets win on some health measures, lose on others, and a lot depends on how carefully you plan what you eat.
Heart Disease Risk Drops, but Stroke Risk May Rise
The clearest advantage of a vegetarian diet is cardiovascular. Vegetarians are about 22% less likely to develop ischemic heart disease compared to meat-eaters, and a meta-analysis of five major studies found a 24% lower rate of death from heart disease specifically. That’s a substantial benefit, driven largely by lower cholesterol levels, lower blood pressure, and less arterial inflammation from saturated fat.
There’s an important caveat, though. The EPIC-Oxford study, one of the largest to track vegetarians over time, found that vegetarians had a 20% higher rate of total stroke, particularly hemorrhagic stroke (bleeding in the brain). The reasons aren’t fully settled, but researchers suspect it may relate to lower levels of certain nutrients that support blood vessel integrity, or to very low cholesterol levels that may reduce the ability of small blood vessels to withstand pressure. So the heart benefits are real, but the cardiovascular picture isn’t uniformly positive.
Diabetes Protection Is Partly About Weight
Vegetarians are consistently less likely to develop type 2 diabetes. Before accounting for body weight, vegetarians in the EPIC-Oxford study were 37% less likely to develop diabetes than regular meat-eaters. In two other large cohorts, the Adventist Health Study and the Tzu Chi Health Study, the reductions were even larger: 54% and 46%, respectively.
Here’s the catch: much of that protection comes from the fact that vegetarians tend to be leaner. After adjusting for BMI, the EPIC-Oxford advantage shrank to 11% and was no longer statistically significant. The Adventist and Tzu Chi studies still showed meaningful reductions after BMI adjustment (38% and 35%), but the pattern is clear. A vegetarian diet helps prevent diabetes in large part because it makes it easier to maintain a healthy weight. If you eat meat but keep your weight in check, the gap narrows considerably.
Cancer Risk and Processed Meat
Skipping meat does remove one well-established cancer risk factor. Replacing unprocessed meat with processed meat (bacon, sausages, deli meats) is associated with a 15% increase in colorectal cancer overall, with even higher risks for specific parts of the colon: 18% higher in the proximal colon and 33% higher in the cecum. The World Health Organization classified processed meat as a Group 1 carcinogen in 2015, putting it in the same evidence category as tobacco for this specific cancer type.
That said, the absolute risk increase from moderate processed meat consumption is small compared to something like smoking. And you don’t need to be vegetarian to avoid processed meat. Someone who eats unprocessed chicken and fish but skips hot dogs and bacon would largely sidestep this particular risk.
Fiber and Gut Health Advantages
Vegetarians eat substantially more fiber than meat-eaters: about 37 grams per day compared to 23 grams for omnivores. Vegans consume even more, averaging 47 grams daily. Since most health guidelines recommend 25 to 30 grams per day and the average American falls well short, this is a genuine advantage. Higher fiber intake is linked to lower rates of colon cancer, better blood sugar control, and healthier cholesterol levels.
That extra fiber also shapes the gut microbiome in favorable ways. Vegetarians have significantly greater bacterial richness in their intestines compared to omnivores, with higher counts of Bacteroidetes, a group of bacteria involved in breaking down complex carbohydrates and producing short-chain fatty acids that nourish the gut lining. A more diverse microbiome is generally associated with stronger immune function and lower levels of chronic inflammation.
Nutrients That Need Attention
Vitamin B12 is the biggest nutritional concern for vegetarians. While deficiency affects roughly 6% of the general population under age 60, rates among vegetarians are dramatically higher, ranging from 11% to as high as 90% in some studies depending on how strictly the diet is followed and how deficiency is measured. Children who have been vegetarian their entire lives are especially vulnerable: one study found a 67% deficiency rate in lifelong vegetarian children compared to 25% in children who adopted the diet later. B12 is essential for nerve function and red blood cell production, and prolonged deficiency can cause irreversible neurological damage. If you’re vegetarian, a B12 supplement or fortified foods are not optional.
Iron is another area where vegetarians face a disadvantage. The body absorbs about 15% of heme iron (found in meat) but only about 7% of non-heme iron (found in plants). That’s roughly half the absorption efficiency. Vegetarians can compensate by pairing iron-rich foods with vitamin C, which boosts non-heme absorption, and by eating more total iron. But without deliberate effort, iron deficiency is more common in vegetarians, particularly in women of reproductive age.
Bone health also deserves attention. A systematic review of 20 studies covering more than 37,000 participants found that both vegetarians and vegans had lower bone mineral density at the hip and spine compared to omnivores, with vegans also showing higher fracture rates. Calcium, vitamin D, and protein all play roles in bone strength, and all three require conscious planning on a meat-free diet.
Protein Quality Is Manageable
One common concern about vegetarian diets is protein adequacy. Protein quality is measured by a score called PDCAAS, which rates how well a protein supplies essential amino acids on a scale from 0 to 1. Animal proteins like beef, eggs, and whey all score at or near 1.00. Soy protein essentially matches them, scoring between 0.93 and 1.00 across multiple analyses. Pea protein scores somewhat lower, around 0.78 to 0.91, but still qualifies as a high-quality source.
The practical takeaway: if you include soy products, dairy, or eggs in your diet, protein quality is a non-issue. Even on a fully plant-based diet, combining different protein sources throughout the day (grains with legumes, for example) provides a complete amino acid profile without much difficulty.
What Actually Matters Most
The evidence points to a consistent pattern: vegetarian diets offer real protection against heart disease and make it easier to maintain a healthy weight, which in turn lowers diabetes risk. They deliver more fiber and promote a more diverse gut microbiome. But they also carry genuine risks around B12 deficiency, lower iron absorption, and weaker bones if you don’t plan carefully.
The fact that overall mortality is identical between vegetarians and meat-eaters in the largest European cohort study suggests that the advantages and disadvantages roughly balance out at a population level. A well-planned vegetarian diet is healthier than a typical Western diet heavy in processed meat and low in vegetables. But a thoughtful omnivorous diet that emphasizes plants, limits processed meat, and includes moderate amounts of fish and lean meat performs similarly on most health outcomes. The gap between the two approaches is smaller than the gap between either one and a diet built on fast food and processed snacks.