Vitamin B12 is a water-soluble vitamin found naturally in some foods and added to others. B12 is necessary for red blood cell formation, neurological functioning and DNA synthesis, according to the Office of Dietary Supplements. Deficiency of Vitamin B12 can cause anemia, a red or sore tongue, heart palpitations, memory problems, depression and tingling in the hands and feet. It can also cause B12 neuropathy, a condition in which the nerve fibers degenerate, leading to irreversible neurological damage. The Vegetarian Society of the United Kingdom states that deficiency is common in vegetarians and vegans, as B12 is found mainly in meat, dairy and eggs.
Animal Products
Meat, poultry, seafood, eggs and dairy products are good nutritional sources of Vitamin B12, according to the Office of Dietary Supplements. Organ meats contain the highest amount, with one slice of braised beef liver providing 48 micrograms (mcg), or 800 percent of the Daily Value (DV), of B12. Trout, salmon, haddock and tuna are excellent fish sources, and a 3 oz. serving of breaded, fried clams provides more than 34 mcg of Vitamin B12, which is 570 percent of the DV. One cup of plain yogurt contains 1.4 mcg, and a single cup of milk contains almost 1 mcg of the vitamin. According to the Vegetarian Society, B12 has very low toxicity and high dosages are generally not harmful to a person's health.
Plant Sources
It is difficult to meet the DV of Vitamin B12 through plant sources alone. In fact, the Vegetarian Society of the United Kingdom warns that no plant source can be considered a safe means of adequate intake. Some B12 is present in soy products, algae and seaweed, but the University of Illinois states that these foods contain an inactive form of B12 that may actually interfere with B12 absorption. The George Mateljan Foundation, a nonprofit group promoting healthy eating, states that brewer's yeast is a good source of the vitamin. Vegetarians can increase their daily intake by taking spirulina supplements.
Fortified Foods
Because Vitamin B12 is found primarily in animal products, risk of deficiency in certain groups, primarily the elderly and strict vegans, is significant. To reduce this risk, many cereals and grains are now available with added B12. Breakfast cereals are the most commonly fortified products, with most containing 6 mcg, or 100 percent of the DV of Vitamin B12. Fortified soymilk, yeast extracts and sunflower and vegetable margarines are other nutritional sources of B12.
References
- Office of Dietary Supplements: Dietary Supplement Fact Sheet: Vitamin B12
- The Vegetarian Society of the United Kingdom: Vitamin B12
- The George Mateljan Foundation, World's Healthiest Foods: Vitamin B12
- National Institutes of Health: Vitamin B12
- University of Illinois, McKinley Health Center: Vitamin B12: What Vegans Need to Know
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