What is a vegan diet?

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Alternative diet that excludes meat, fish, eggs, honey, and dairy products.
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The vegan diet can also be called strict vegetarianism because it excludes not only meat and fish but also eggs, honey, and milk (dairy) products. Many practitioners of the vegan diet additionally avoid the use of animal products in other forms, such as clothing (wool, leather, silk), jewelry (pearls) and cosmetics (lanolin). People who adopt veganism may do so for health reasons, ethical considerations, or both.

There are several forms of veganism, and these may disagree on various major and minor points. For example, the raw-food diet and the macrobiotics diet are both vegan, but while macrobiotic practitioners believe that raw food is unhealthy, raw-foodists believe that cooked food is the source of many health problems.

The word “vegan” was created in 1944 by Elsie Shrigley and Donald Watson, “pure” vegetarians who were annoyed that many people who called themselves vegetarian ate dairy products and even fish. They combined the first three and last two letters of the word “vegetarian” to form “vegan,” thereby intending to indicate that veganism was “the beginning and end of vegetarian.”

Scientific Evidence

Some proponents of veganism claim that a vegan diet can cure many health conditions. However, in attempting to scientifically verify such claims, one runs into a significant problem: It is difficult, if not impossible, to design a scientifically reliable study of diet. For the results of a study to be trustworthy, participants and researchers must not know (be “blinded”) who received the treatment under study (the active group) and who received a placebo treatment (the control group). If practitioners and researchers know who is in which group, numerous confounding factors will take over and produce misleading results. These factors include observer bias, reporting bias, and the placebo effect. To briefly summarize this complex issue, unblinded studies usually mean little to nothing. It is difficult to keep knowledge of the vegan diet from study participants.

Uses and Applications

Those who adopt veganism for health reasons may do so for a variety of desired outcomes, from general health to targeting specific disorders. Rheumatoid arthritis is the prime condition for which veganism has been advocated. In several studies, people put on a vegan diet showed improvement in symptoms compared with those who were allowed to eat in an ordinary fashion. However, the absence of blinding makes these results unreliable. These studies would have been more meaningful if, for example, all participants ate a vegan diet and in addition consumed cookies that, without participants’ knowing, contained either animal or vegetable fats. No studies using this or any other properly blinded control treatment have been reported.

A small study of similarly inadequate design weakly hints that a vegan diet might be helpful for fibromyalgia. Another small study compared a vegan diet to an antidepressant for treatment for fibromyalgia, and the antidepressant appeared to be more effective. Here, however, unconscious bias may have been working in the opposite direction: This study was conducted in Bangladesh, where a vegan diet is not exceptional, whereas the Western drug used could have had something of an aura. Even weaker evidence hints that vegan diets might be helpful for treating hypertension and for preventing heart disease and cancer.

While there is no definitive evidence that a vegan diet may be used to target a specific disease, general health trends have been observed among vegans and nonvegans. Studies have found that, in general, vegans as well as vegetarians have a smaller chance of being obese or overweight than nonvegans. They typically also have lower cholesterol and blood pressure and lower risk of type 2 diabetes.

In 2014, a study published in the journal Nutritional Neuroscience suggested that men and women who follow a vegan diet experience less stress and anxiety than omnivores. The authors of the study hypothesized that these results could have something to do with the high amounts of antioxidants found in fruits and vegetables. Vegan participants also reported consuming fewer sweets than those who eat meat; the consumption of sweets had correlated with higher levels of stress.

Safety Issues

A vegan diet can in principle provide all necessary nutrients, with the exception of vitamin B12 . However, in practice, vegans are frequently deficient in calcium, iron, vitamin D, selenium, phosphorous, and zinc.

Vitamin B12 presents a special issue. This bacterially-produced vitamin is not provided to any meaningful extent by plant foods. (The alga spirulina contains B12, but in a nonabsorbable form.) Deficiency in B12 is therefore widely thought to be inevitable among those who follow a strict vegan diet and who do not take supplements. Such deficiency has led to serious health consequences among vegans and among breast-fed infants of vegan mothers. When severe, B12 deficiency can cause irreversible nerve damage. Mild deficiency leads to anemia and, in association with other common deficiencies, increased risk of bone thinning and fracture. However, some vegan advocates argue that supplements are not needed to maintain adequate B12 levels.

There is an additional potential issue for athletes to consider: A vegan diet is very low in the nonessential nutrient creatine. It is possible that creatine supplements may be particularly helpful for vegan athletes.


Watson and others formed the Vegan Society in England in 1945, and the movement grew slowly as a subset of vegetarianism. In the 1970s, shifting social, political, and scientific attitudes helped contribute to increasing interest in animal-free diets, particularly in the United States. Both ethical and dietary forms of veganism gained followers and public awareness. However, it was not until the 2000s and 2010s that veganism began to be accepted as a mainstream phenomenon. During this time restaurants reported a surge in the popularity of vegan options, popular media covered various issues related to veganism, and analyses of online search activity suggested increased public interest in learning about veganism. Still, a 2012 Gallup poll found only 2 percent of Americans self-identified as vegans, while the 5 to 6 percent that identify as vegetarian remained stable from 1999 to 2012. According to a study by the Heinrich Böll Foundation and Friends of the Earth, as reported by the Guardian, still only about one in fifty Americans claimed to be vegan as of 2014.


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