Vegetarian Diet: Health Benefits, Risks and Nutrient Gaps

October 30, 2026

A well-planned vegetarian diet is linked to lower blood pressure, lower LDL cholesterol, a lower risk of type 2 diabetes and fewer heart disease deaths. The main risks are shortfalls in vitamin B12, iron, omega-3 fats and, for vegans, calcium and vitamin D. Fortified foods, smart pairings and sometimes a supplement close those gaps.

This guide is for anyone who has gone vegetarian, is thinking about it, or cooks for someone who has, and wants the honest trade-offs rather than a sales pitch.

Key takeaways

Harvard Health reports that a pooled analysis of five studies with over 76,000 people found vegetarians were about 25% less likely to die of heart disease.
Vitamin B12 occurs naturally only in animal foods, so vegans and people who eat few eggs or dairy foods need fortified foods or a supplement.
The NIH says vegetarians who eat no meat, poultry or seafood need almost twice as much iron as the standard recommendation, because plant iron is absorbed less well.
Plant omega-3 (ALA) converts to EPA and DHA only in very small amounts, so algal oil is the vegetarian route to those fats.
A vegetarian diet built on refined snacks, sweets and cheese pizza does not deliver the health benefits seen in studies.

What counts as a vegetarian diet?

A vegetarian diet leaves out meat, poultry and fish, though the exact rules vary by type. Knowing your type tells you which nutrients need the most attention.

Harvard Health describes these common patterns:

Type	What it includes	Main nutrients to watch
Lacto-ovo vegetarian	Plants, eggs and dairy	Iron, omega-3 (EPA and DHA)
Lacto vegetarian	Plants and dairy, no eggs	Iron, omega-3
Ovo vegetarian	Plants and eggs, no dairy	Iron, calcium, omega-3
Vegan	Plants only, no eggs, dairy or gelatin	B12, iron, calcium, vitamin D, omega-3, protein variety
Partial (pescatarian or pollo-vegetarian)	Plants plus fish or poultry	Usually few gaps if fish is eaten

A vegan diet is the strictest form, with no animal products at all. The fewer animal foods you eat, the more deliberately you have to plan.

What are the health benefits of a vegetarian diet?

Vegetarians tend to have lower blood pressure, lower LDL cholesterol and a lower body mass index, and studies link the pattern to less heart disease and type 2 diabetes. The cancer link is weaker.

Here's what the evidence summarized by Harvard Health shows:

Heart disease. In a combined analysis of five studies, vegetarians were about 25% less likely to die of heart disease. A separate study of about 65,000 people found a 19% lower risk, though there were too few deaths to rule out chance.
Type 2 diabetes. In studies of Seventh-day Adventists, vegetarians had about half the diabetes risk of nonvegetarians, even after accounting for body weight.
Cancer. Vegetarians may have slightly lower cancer rates, but results are inconsistent and the difference is small.

Two caveats keep this honest. First, vegetarians also tend to smoke less, drink less and exercise more, so it's hard to credit diet alone. Second, much of the benefit comes from what you add, such as beans, vegetables, whole grains and nuts, not simply from removing meat. Fiber is a good example: most of it comes from plants, and our guide to high-fiber foods and what they do for you shows how quickly it adds up on a plant-heavy plate.

What are the risks of a vegetarian diet?

The real risks are nutrient shortfalls, not the absence of meat itself. B12, iron and long-chain omega-3 fats are the big three, with calcium, vitamin D and protein variety mattering more for vegans.

Vitamin B12

Vitamin B12 is a vitamin your body needs to make red blood cells and keep nerves healthy. The NIH Office of Dietary Supplements sets the adult target at 2.4 mcg a day, rising to 2.6 mcg in pregnancy and 2.8 mcg while breastfeeding. Plant foods contain no B12 unless it has been added. Deficiency signs include fatigue, weakness, pale skin, numbness or tingling in the hands and feet, balance problems, a sore tongue and memory trouble. Because the body stores a large reserve, symptoms can take years to appear, and nerve damage can happen even without anemia.

Lacto-ovo vegetarians who eat eggs or dairy regularly usually get enough, according to the NHS. Vegans need fortified foods such as fortified cereals, plant milks, nutritional yeast and yeast extracts, or a supplement.

Iron

Plant foods contain nonheme iron, the form your body absorbs less efficiently than the heme iron in meat. The NIH lists 8 mg a day for men and 18 mg for women aged 19 to 50, and says vegetarians need almost twice those amounts. The NHS notes vegetarians are more likely to have lower iron stores. If you've felt drained since cutting out meat, our piece on why some people feel exhausted after switching to plant-based eating covers iron and the other usual suspects.

Omega-3 fats

Flaxseed, chia seeds, walnuts and canola oil provide ALA, a plant omega-3. The NIH suggests about 1.6 g of ALA a day for men and 1.1 g for women, but your body turns only very small amounts into EPA and DHA, the forms found in fish. Algal oil supplies those directly. For a deeper look, read whether plant foods can really replace salmon for omega-3s.

Calcium, vitamin D and protein

Harvard Health reports that lacto-ovo vegetarians get about as much calcium as meat eaters, while one study found 75% of vegans fell short. Kale, broccoli, calcium-set tofu and fortified plant drinks help; spinach and chard are poor sources because their calcium is hard to absorb. If you still eat dairy, our review of dairy's nutrition pros and cons is worth a read. Vegans may also need fortified foods or a vitamin D supplement. Most vegetarians meet protein needs, but variety matters, and you can work out your own target with our guide to how much protein you need per day.

How do you plan a balanced vegetarian diet?

Build each meal around a protein source, a whole grain or starchy food, and plenty of vegetables, then make sure B12, iron and omega-3 have a reliable source every day.

Anchor every meal with protein. Rotate beans, lentils, chickpeas, tofu, tempeh, eggs, dairy, nuts and seeds. The NHS recommends eating a variety of protein sources to get the right mix of amino acids.
Pair iron with vitamin C. The NIH says plant iron absorbs better alongside citrus, strawberries, sweet peppers, tomatoes or broccoli. Lentil soup with a squeeze of lemon, or bean chili with peppers, does the job.
Lock in a B12 source. Check Nutrition Facts labels for added B12 on cereals and plant milks, or use a supplement if you eat few animal foods.
Add a daily omega-3 food. A spoon of ground flaxseed or chia, or a handful of walnuts. Consider algal oil if you eat no fish.
Cover calcium. Dairy, fortified plant drinks, calcium-set tofu and leafy greens such as kale.
Keep the base whole. The NHS suggests at least 5 portions of fruit and vegetables a day and making starchy foods, preferably wholegrain, just over a third of what you eat.
Review supplements once. Decide what food can cover and what it can't. Our guide to finding the right balance between real food and supplements walks through that decision.

A simple day might look like this: oats made with fortified soy milk, topped with ground flaxseed and berries; a lunch of lentil and vegetable soup with wholegrain bread and an orange; tofu and broccoli stir-fry with brown rice for dinner; and walnuts or yogurt as a snack.

Common mistakes on a vegetarian diet

Most problems come from swapping meat for refined carbs and cheese rather than for beans, grains and vegetables.

Calling junk food vegetarian. Harvard Health points out that soda, cheese pizza and candy are technically vegetarian but not healthy. Calories still count, and excess calories from plant foods can cause weight gain.
Ignoring B12 for years. Because stores last a long time, people feel fine until nerve symptoms appear.
Relying on spinach for iron and calcium. It has both, but much of it isn't well absorbed.
Assuming ALA equals fish oil. The conversion is too small to count on.
Overlooking children and pregnancy. The NIH warns that babies of mothers on strict vegetarian or vegan diets may fall short on B12. For younger eaters, see whether plant-based kids actually need supplements.

When to see a doctor

See your doctor if any of these show up after changing your diet, or at any time:

Numbness, tingling or pins and needles in your hands or feet, or problems with balance
Ongoing tiredness, weakness, shortness of breath on light effort, pale skin or a racing heartbeat
A sore, red or smooth tongue, or new memory problems or confusion
Unplanned weight loss or loss of appetite
Heavy periods while eating a meat-free diet, which raises iron needs
You are pregnant, breastfeeding or planning a pregnancy and eat a vegan or near-vegan diet

A simple blood test can check B12 and iron levels. Don't start high-dose iron on your own without testing, since too much can be harmful.

FAQ

Is a vegetarian diet healthier than eating meat?

It can be. Studies link well-planned vegetarian diets to lower heart disease death, less type 2 diabetes, lower blood pressure and lower LDL cholesterol. But a Mediterranean-style diet with plenty of plants and little meat offers many of the same benefits, and a vegetarian diet built on refined foods does not. The quality of what you eat matters more than the label.

Do vegetarians need to take vitamin B12?

Vegans almost always do, through fortified foods or a supplement, because B12 occurs naturally only in animal foods. Lacto-ovo vegetarians who regularly eat eggs and dairy usually get enough, but anyone eating small amounts of these foods should check labels for fortified products or ask a doctor about testing, especially before or during pregnancy.

Can you get enough protein as a vegetarian?

Yes, most vegetarians do. Eggs, dairy, beans, lentils, tofu, tempeh, nuts and seeds all supply protein. Vegans should eat a variety of these across the day so they get a full mix of amino acids. Active people, older adults and anyone on a calorie-restricted diet may need to plan protein more carefully.

Why am I tired after going vegetarian?

Common reasons are low iron, low B12 that has been building for a while, eating too few calories, or replacing meat with refined carbohydrates that don't keep you full. Pairing plant iron with vitamin C, adding a reliable B12 source and building meals around protein often help. If tiredness persists for more than a few weeks, ask your doctor for blood tests.

What to do next

Write down your vegetarian type, then check the table above for the nutrients you most need to cover.
Pick one fortified food or supplement for B12 and use it daily.
Add a vitamin C food to every iron-rich meal this week.
If you've been vegetarian for a year or more and never had bloodwork, ask your doctor to check B12 and iron at your next visit. To time any supplements well, see our vitamin timing guide.

This article is for general information and is not medical advice. Talk to a doctor or registered dietitian before making major diet changes, especially if you are pregnant, have a health condition or take medicines.

Sources

Last reviewed: October 2026.

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