A vegan diet does not permit any foods derived from animal sources, such as meat, dairy products and eggs. Some vegans also avoid honey and gelatin, as well as products produced using animal byproducts, such as commercially produced wines and refined sugar. Vegans represent between 0.3 and 1 percent of the U.S. population, according to the Vegetarian Resource Group. A vegan diet eliminates the saturated fats and chemicals found in animal products; however, vegans may need to take certain vitamins to avoid deficiencies.
Vitamin B-12, a B-complex vitamin, helps convert carbohydrates in foods into energy for cellular repair and physical tasks, according to the University of Maryland Medical Center. It also helps your body produce fats that coat and protect nerve endings, preventing damage from toxins and free radicals. A vitamin B-12 deficiency may result in irreversible nerve damage. Because vegans do not eat animal products, the only reliable food sources of vitamin B-12, vegans may require supplements to avoid a B-12 deficiency.
Sources of vitamin D include fish, cod liver oil, eggs and fortified dairy products. Plant foods do not provide a natural source of vitamin D, which puts vegans at risk for deficiency. Vitamin D helps your body absorb and use calcium to build and maintain strong bone cells, according to the University of Maryland Medical Center. It may also decrease the risk of falling, particularly among senior citizens. A deficiency of vitamin D may allow calcium build up in your arteries, which increases your risk of heart disease and stroke.
Niacin, also known as vitamin B-3, aids in proper blood circulation, helping your body deliver oxygen, vitamins and minerals to organ, bone and muscle cells. It also helps your body metabolize nutrients such as carbohydrates and fats derived from food sources. Though primarily found in eggs, milk, beef liver and fish, according to Phyllis Balch, author of "Prescription for Nutritional Healing," vegans may derive small amounts of niacin from potatoes, tomatoes and peanuts. However, they may require supplements to ensure proper niacin intake.
Omega-3 Fatty Acids
Among its many uses in your body, omega-3 fatty acids build cell membranes in your brain, regulate neurotransmitter transmission, support anti-inflammatory compounds and control blood clotting. As an essential omega-3 fatty acid, alpa-linolenic acid, or ALA, must come from dietary sources, which include flaxseed, flaxseed oil, canola oil, tofu, soybeans, walnuts and green leafy vegetables. ALA helps produce two other omega-3 fatty acids, eicosapentaenoic acid, also called EPA, and docosahexaenoic acid, or DHA. However, ALA uses an inefficient process to produce EPA and DHA that may not serve your body's omega-3 needs, according to Colorado State University. Because EPA and DHA play major roles in preventing heart disease, decreasing your body's ability to produce triglycerides and improving blood pressure, vegans can obtain them from supplements or fortified foods, such as orange juice and margarine.