Highlights

• Vegan diets only include plant-based foods.
• Research has shown that vegan or vegetarian diets rich in plant-based foods are associated with lower LDL cholesterol, improved blood glucose and improved blood pressure.
• There are a few nutrients that individuals following a vegan diet should be mindful to get enough of, including vitamin B12, calcium, iron and certain omega-3 fatty acids.

The Basics

Vegan and vegetarian diets appear to be among the top food trends, but there is evidence that some people have been eating a predominantly plant-based or vegetarian diet for centuries. However, it wasn’t until 1944 that the term “vegan” was coined. Essentially, individuals who follow a vegan diet have opted to remove all animal-based foods from their diet. Many choose vegan clothing, household items and personal care items as well. Most individuals who adopt a vegan diet are doing so for the perceived health benefits or to advocate for animal rights.

What Foods Make Up a Vegan Diet?

Vegan diets are made up of only plant-based foods. This type of diet includes fruits, vegetables, soy, legumes, nuts and nut butters, plant-based dairy alternatives, sprouted or fermented plant foods and whole grains. Vegan diets don’t include animal foods like eggs, dairy, meat, poultry or seafood. They also are devoid of animal byproducts such as honey (made by bees) and lesser-known animal-based ingredients like whey, casein, lactose, egg white albumen, gelatin, carmine, shellac, animal-derived vitamin D3 and fish-derived omega-3 fatty acids.

Veganism and Health

The foods emphasized in a vegan diet are rich in many nutrients like vitamins A, C, E and K, fiber, antioxidants and phytonutrients. Vegan diets have been studied for their impact on human health. Below are some highlights.

Research

One randomized controlled trial (RCT) examined the impact of a vegan, no-added-fat diet on cardiovascular risk in obese children with hypercholesterolemia and their parents. The results found that children and parents who had adopted this diet had lower total cholesterol, blood pressure and BMI compared to baseline. Another RCT found that vegan diets were associated with improved glycemic control compared to a conventional diabetes diet in individuals with Type 2 diabetes. Lastly, a 74-week RCT – albeit with a small sample size – found a low-fat vegan diet appeared to improve glycemia and plasma lipids more than a conventional diabetes diet. Larger and long-term follow up studies are needed to support these findings.

Health benefits of vegan diets have also been noted in observational studies. One systematic review of cross-sectional and prospective cohort studies reported lower body mass index, total cholesterol, LDL cholesterol (or “bad” cholesterol) and blood glucose levels in individuals following vegetarian or vegan diets compared to omnivores. The results of the studies specific to people on a vegan diet indicated that this eating pattern reduced the overall cancer risk by 15 percent. Although cross-sectional and cohort studies cannot prove cause and effect (as in, a vegan diet causes health benefits), these findings support the results of RCTs, which are considered to be the gold standard of research and are designed to demonstrate that an intervention (following a vegan diet) leads to an effect (health benefits).

Most of this research has garnered positive results. Still, understanding the specific effects of vegan diets on health remains challenging because research on this eating pattern is often grouped together with vegetarian or plant-based diets, both of which may include animal products.

Nutrients of Concern

While the vegan diet can be very nutrient-rich, there are a few nutrients to be particularly aware of when adopting this style of eating: most notably vitamin B12, calcium, certain omega-3 fatty acids and iron.

Vitamin B12 is important for metabolism, heart, nerve and muscle health and it’s mostly found in animal products. Those following a vegan diet should opt for foods fortified with B12. Moreover, individuals following a vegan diet should communicate with a health care provider about monitoring their levels of B12 and their potential need for a supplement, keeping in mind that a deficiency in B12 could take years to manifest on a blood test.

Calcium is essential for dental, nerve, bone and muscle health and it is best absorbed with vitamin D. This nutrient is found predominantly in dairy foods and in lesser amounts in leafy greens like kale and broccoli. It is also found in fortified foods, such as tofu, bread and plant-based dairy alternatives. A systematic review found that individuals following a vegan or vegetarian diet had lower bone mineral density and higher fracture rates. Because calcium and vitamin D are key to bone health, those on a vegan diet are advised to talk to their healthcare provider to determine whether a supplement may be necessary.

Iron is a vital component of metabolism and heart health. It is found mostly in animal foods. Although fortified whole grains, beans, lentils, spinach and other plant-based foods provide iron, it’s in the form of non-heme iron, which is not as bioavailable as the heme iron found in animal foods.

Omega-3 fatty acids are a type of polyunsaturated fat shown to support cardiovascular health. The three most common types we eat are alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA is found in plant sources like flaxseed, chia seeds and walnuts, but EPA and DHA are found mainly in animal foods with the exception of some marine plant sources. ALA is converted by our bodies into EPA and DHA, but only in small quantities. Vegan options for EPA and DHA are microalgae and seaweed food products or supplements.

Interested in learning the basics of other food, nutrition and health topics? Check out our “What Is” series.

This article includes contributions by Kris Sollid, RD and Ali Webster, PhD, RD