Vegetarian and Vegan Diet

  • Author:
    Betty Kovacs, MS, RD

    Betty is a Registered Dietitian who earned her B.S. degree in Food and Nutrition from Marymount College of Fordham University and her M.S. degree in Clinical Nutrition from New York University. She is the Co-Director and Director of nutrition for the New York Obesity Research Center Weight Loss Program.

  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Quick GuideVegetarian Diet Pictures Slideshow: Becoming a Vegetarian

Vegetarian Diet Pictures Slideshow: Becoming a Vegetarian

Vitamin B12

Vitamin B12 is attached to the protein in animal foods. There has been considerable research to determine if it is also found in some plant foods. Unfortunately, the B12 that has been found in plant foods can't be used by humans. Supplements that have been made with the plant sources have been shown to contain B12 analogues, compounds that are structurally similar to B12 but do not serve the same function. Research has shown that using supplements with these analogues can actually compete with vitamin B12, inhibit its metabolism, and increase the risk of B12 deficiency.

Vitamin B12 deficiency causes a number of symptoms and problems, including weakness, tiredness, constipation, loss of appetite, weight loss, poor memory, dementia, depression, problems with balance, and megaloblastic anemia. You may also experience nerve problems, such as numbness and tingling in the hands and feet. Vitamin B12 deficiency can damage the nervous system even in people who don't have anemia, so it is important to treat a deficiency as soon as possible.

Vitamin B12 is found in seafood, dairy, eggs, and meat. Vegan diets have the highest risk of deficiency. There are many foods that are fortified with vitamin B12, so it is possible for vegan diets to contain adequate amounts of this nutrient with or without a supplement. The recommendations for reaching your vitamin B12 needs are to

  1. consume food fortified with vitamin B12 two to three times a day,
  2. take a B12 supplement if you are unable to consume an adequate amount in your diet or if you have an increased need for it (the elderly and pregnant and lactating women),
  3. do not take excessive amounts of folate supplements, as this can mask a B12 deficiency,
  4. have your B12 level checked by your physician.
Medically Reviewed by a Doctor on 4/8/2015
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