Your body needs vitamin B-12 to make DNA, the genetic material in your cells. This vitamin also assists in making red blood cells that carry oxygen around your body. The Food and Nutrition Board of the Institute of Medicine has established recommended dietary allowances for B-12 to prevent deficiencies. The amount you need depends on your age, lifestyle and gender.
Recommended Allowance
In the U.S., the average intake of B-12 is 3.5 mcg for women and 5 mcg for men, higher than the recommended allowance, according to the U.S. Department of Agriculture. Adults and teenagers ages 14 and older require 2.4 mcg of B-12 per day. The RDA is 1.8 mcg for children ages 9 to 13, 1.2 mcg for ages 4 to 8 and 0.9 mcg for ages 1 to 3. Infants ages 6 months and under require 0.5 mcg, while ages 7 to 12 months require 0.5 mcg. The RDA is 2.6 mcg for pregnant women and 2.8 mg for breastfeeding mothers.
Deficiency
A deficiency in B-12 is caused by a low dietary intake of this nutrient, such as a vegetarian diet. A deficiency can also be caused by the inability to absorb B-12 efficiently, such as with celiac or Crohn's disease. Adults over age 50 and people who have had gastrointestinal surgery may also have difficulty absorbing B-12. Low levels of B-12 can lead to anemia, loss of balance, dementia or nerve damage.
Dietary Sources
B-12 is naturally found only in animal sources such as beef liver, seafood, eggs, chicken and lamb. For example, beef liver provides 800 percent of the recommended dietary allowance in one slice. Seafood selections include clams, trout, oysters, salmon and sardines. The USDA lists milk, cheese and yogurt as rich sources of B-12. Choose nonfat or low-fat versions for a healthier option.
Considerations
If you are vegetarian, select foods that have B-12 added to them, such as soy products, breakfast cereals, noodles, yeast and meat substitutes. Many breakfast cereals provide 100 percent of the daily value in one serving. Check the package label for further details. B-12 is found in most multivitamin supplements or in supplements containing other B vitamins, such as folic acid and biotin. You can also take B-12 by injection or in a nasal gel.
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