A vegan diet has only one rule: no animal products.
This takes the vegetarian diet one step further by also removing eggs, dairy, and honey from your plate.
A person who follows a vegan diet is known as a vegan — a term first coined by Watson and Morgan in 1944.
But veganism can be more than just a diet: The Vegan Society defines veganism as “a philosophy and way of living which seeks to exclude — as far as is possible and practicable — all forms of exploitation of, and cruelty to, animals for food, clothing or any other purpose.”
That said, it’s important to mention that the most popular motive for becoming vegan is not health, but animal welfare. Click here to read more about why vegans are motivated to avoid animal products.
A vegan diet is defined by what it excludes: animal products.
Sounds simple, but this raises the question: What should vegans eat instead?
To answer this question, take a look at a healthy food plate as recommended by the German Nutrition Society:
*Adapted from the German Nutrition Society (Deutsche Ernährung für Gesellschaft, DGE) 
For omnivores, 75% of a healthy food plate is already plants (cereals, vegetables, fruits, and fats). The remaining 25% is made up of animal products (mostly dairy and, to a smaller extent, eggs, meat, and fish). In other words, the difference between a healthy vegan and a healthy omnivore diet is only a quarter of a healthy food plate.
For a vegan diet, this remaining 25% of animal products could be replaced as follows:
Plant-based milk, yogurt, and cheese alternatives can substitute dairy products.
Flax seeds are a good replacement for eggs when baking.
Tofu, tempeh, and other plant-based substitutes can replace meat and fish.
Peas, lentils, and legumes are also valuable protein sources for vegans.
Nuts and seeds provide essential nutrients and are a tasteful add-on to a meal.
Even meals that contain a lot of animal products can be made vegan with some effort and creativity. For instance, a vegan alternative to eggs with bacon and cheese is a plate of scrambled tofu with smoked seitan and cashew-based vegan cheese.
However, some critics have argued that vegan substitute products are not as healthy as "real" animal and dairy products. However, this is not necessarily the case. For example, rumors have demonized soybeans and processed soy products for (allegedly) lowering men’s testosterone levels, impairing thyroid function, and raising the risk of Alzheimer’s disease. Click here to find out why this is probably not the case.
The umbrella term “plant-based diet” is often used synonymously to a vegan diet — with a caveat.
While veganism is clearly defined in a nutritional context (no animal products are eaten), the definition of a “plant-based diet” varies widely when used in research. For example, a review of 44 studies found that more than half of the prescribed plant-based diets were not strictly vegan because they allowed for small amounts of animal products, such as fish or dairy.
This ambiguity around the term “plant-based diet” is important to keep in mind in order to analyze research studies accurately. This page uses the term ‘vegan’ instead of ‘plant-based’ to avoid such confusion.
Even though eating a large variety and amount of plant foods is healthy, a vegan diet per se is not necessarily healthy — but it certainly can be. But what makes a vegan diet healthy?
As discussed in the previous question, a healthy vegan diet is based on whole foods and ideally includes a variety of food sources to ensure all critical nutrient needs are met. Appropriate supplementation can also help. If this is the case, a vegan diet is not only healthy, but may even have some advantages over a standard omnivorous diet.
First, a vegan diet can be more satiating than a regular omnivorous diet. This is because vegans eat more fiber-rich, low-calorie plant foods while avoiding nutrient-dense, processed animal products. Consequently, vegans often consume fewer calories than people eating a regular diet.
Second, a vegan diet may lower the risk of certain lifestyle diseases. For instance, a plant-based diet is linked to lower incidence and mortality from ischemic heart disease (-25%) and incidence from total cancer (-8%), according to a comprehensive meta-analysis of 86 cross-sectional and 10 prospective cohort studies.
To find out more about how a vegan diet could reduce the risk of lifestyle diseases, click here.
Overall, a vegan diet — if it is well designed — can be considered healthy. However, it’s unclear if a vegan diet is healthier than an omnivorous diet, assuming both diets are well designed. In the context of the current body of literature, claims that imply the superiority of a vegan diet over an omnivorous diet lack any scientific basis.
There are two main drawbacks to a vegan diet. First, a vegan diet can be restrictive and inflexible, making it more effortful to adhere to for some people — though not for everyone — than an omnivorous healthy diet. Second, a vegan diet, if it is not well designed, can result in nutrient deficiencies, thus causing undesired health outcomes.
The art of adopting and sustaining a vegan diet boils down to two aspects: transitioning to a new lifestyle and getting enough critical nutrients, some of which may be sparse in a purely plant-based diet.
Adapting to a new vegan lifestyle mainly revolves around the challenges of eating in a new way, both outside and at home, and abstaining from animal products entirely. This can be a difficult habit to break, since most people have probably been eating animal products since childhood.
New vegans may need to find new favorite meals and restaurants, not to mention overcome all the awkward conversations with friends and family, explaining repeatedly why you are ordering tofu instead of spare ribs. Clearly, “it ain’t easy eating greens,” as researchers investigating the attitude of omnivores toward vegetarians and vegans put it. This phenomenon of aversion to, or dislike of, vegetarians and vegans (also called vegaphobia) can lead to social friction with friends or family members.
Eating at home, though, also poses challenges. Adopting a vegan diet requires learning to cook nutritious meals without any animal products, which can be difficult, at first. Plant-based meat and dairy substitutes such as tofu and soy milk can help make the transition easier. However, you may also want to explore new plant-based foods to bring your vegan cooking skills to the next level.
Since there are certain nutrients that are more difficult to obtain on a vegan diet, compared to an omnivorous diet, eating an unbalanced vegan diet may lead to nutrient deficiencies.
The most important nutrients to consider when eating a vegan diet are:
Vitamins B2, B3, B12, and D
The minerals zinc, calcium, iodine and selenium
Protein and omega-3 fatty acids.
If you want to learn more about these critical nutrients and how to obtain them through a vegan diet, click here.
Overall, the two major challenges of a vegan diet — adopting the habit of eating a new diet that may be more restrictive than an omnivorous diet while still covering all essential nutrients — can be difficult at first. However, these drawbacks can be overcome once you have adapted to your new lifestyle and learned what foods and supplements to consume on a regular basis to avoid nutrient deficiencies.
A vegan diet may affect your body in a variety of ways.
First, adopting a vegan diet may change the quality and quantity of the foods and nutrients you consume:
Macronutrients (proteins, carbohydrates, and fats)
Micronutrients (vitamins, minerals, and phytochemicals)
Other dietary compounds (antibiotics, chemicals, heavy metals)
These differences may affect different aspects of your body and health. To date, the best-studied effects of a vegan diet include changes in body composition, glucose and fat metabolism, and cardiovascular health:
Body composition (discussed in more detail here)
In children, a vegan diet can be safe if all critical nutrients are met, leading to normal growth and development.
In infants, there is a lack of evidence regarding whether a vegan diet is appropriate for normal growth and development.
Improved fat metabolism and blood lipids such as total cholesterol and LDL. However, HDL may be decreased, and triglycerides may be increased for a vegan diet.
Cardiovascular system (discussed in more detail here)
Notably improved risk factors of cardiovascular disease, such as blood lipids.
Also, a vegan diet may affect cognition and mental health, inflammation status, and the gut microbiome. However, more solid evidence is needed to draw any strong conclusions.
Cognition and mental health
Unclear effects on cognitive abilities (e.g., logic and memory) due to a lack of studies.
Potentially small positive effects on certain aspects of mental health (e.g., stress, anxiety, and depression), but more evidence is needed to investigate this effect.
Linked to lower inflammatory markers, such as c-reactive protein (hs-CRP) and interleukin-6.
Small, short-term clinical trials suggest that an improved inflammatory status (among other factors) may be one mechanism by which a vegan diet may alleviate some of the symptoms in certain diseases, such as ﬁbromyalgia and rheumatoid arthritis. More research is needed to confirm these findings.
Gut microbiome (discussed in more detail here)
Evidence from cross-sectional studies is mixed and indicates that there is no consistent association between a vegan diet and microbiota composition.
Researchers have been interested in studying the underlying mechanisms of a vegan diet to better understand its positive health effects.
Generally speaking, these mechanisms describe either direct or indirect effects (see sidebar).
Three potential mechanisms are: higher dietary fiber intake, higher phytochemicals intake, and lower calorie intake.
First, a higher intake of dietary fiber — defined as non-digestible carbohydrates that pass through the intestines to be excreted unaltered or fermented by intestinal microbes — is associated with improved health outcomes. In a vegan diet, dietary fiber intake is increased compared to a classical omnivorous diet due to a higher consumption of fruits, grains, legumes, and vegetables. This increased intake of dietary fiber is hypothesized to have positive effects on the body, including improved short-chain fatty acid production and favorable fermentation processes in the intestines (e.g., upregulated carbohydrate fermentation and downregulated protein fermentation).
The second mechanism that could explain the positive health effects associated with a vegan diet is a higher intake of phytochemicals from fruits and vegetables. In general, a higher intake of phytochemicals — which can only be found in plants, not animals — has proven anti-inflammatory and immune-enhancing effects. As such, it is not surprising that phytochemical intake is linked to a number of beneﬁcial health effects. Consequently, researchers hypothesized that, since a vegan diet provides more phytochemicals than an omnivorous diet, phytochemicals could partially explain the positive health effects of a vegan diet.
Lastly, a vegan diet tends to be lower in calories compared to a normal omnivorous diet, which may also explain a large chunk of its associated health benefits. Besides obvious effects on weight-related disease factors, such as improved cardiovascular risk and glycemic control, caloric restriction potentially induces benefits for cellular mechanisms, such as autophagy, apoptosis, and lower oxidative stress.
Even though these three mechanisms explain some of a vegan diet’s health benefits, the picture remains complex, with many caveats.
On the one hand, it’s difficult to boil down the entirety of health benefits to a single factor, like a nutrient or group of nutrients. Instead, nutrients may have additive or even synergistic effects.
On the other hand, individual differences in genetics and lifestyle further complicate the picture: what may be healthful for one person may be detrimental for another.
More research is needed to better understand the mechanisms that could explain the observed positive health effects that a vegan diet has on the body.
The proverbial saying ‘you are what you eat’ has become a cliché to describe the importance of eating the right foods. However, while it’s technically true that eating the right foods is healthy, it’s also true that avoiding the wrong kinds of food is equally important for your health.
This is where direct and indirect effects come in. These are the changes in nutrients that are added or increased (direct effects) and removed or reduced (indirect effects) when adopting a new diet. Both effects can lead to positive and negative health outcomes.
Direct effects: On the one hand, adopting a vegan diet may increase vitamin C and phytochemical intake, leading to direct benefits for the immune system. On the other hand, eating large amounts of processed meat substitutes may skyrocket sodium and saturated fat intake beyond the recommended levels, leading to direct detrimental health effects.
Indirect effects: On the one hand, a vegan diet — if not well planned — may reduce calcium and vitamin D3 intake, leading to indirect negative effects on bone health. On the other hand, a vegan diet may exclude potentially dangerous dietary compounds, such as opioid-peptides derived from casein, carry-over antibiotics found in animal products, or food-related carcinogenic toxins (e.g., dioxin in eggs or nitrosamines in processed meat), leading to indirect positive health effects.
That said, it becomes evident that eating a vegan diet — like every other healthy diet — is a balancing act: eating the right amounts of healthy foods and nutrients while avoiding a detrimental surplus of any nutrient. This simple, but not simplistic, idea sounds trivial in theory but can be complex in practice. If you want to learn more about the critical nutrients in a vegan diet, click here.