Recommended Daily Allowance
The Institute of Medicine's Food and Nutrition Board recommends that healthy adult men and women over 19 years old consume 2.4 micrograms of vitamin B-12 each day. Pregnant women need 2.6 micrograms daily and women who are breastfeeding need 2.8 micrograms daily. However, due to absorption rate decreasing with age, people over age 50 may need as much as 500 to 1,000 micrograms of supplemental vitamin B-12 each day.
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Examples of good sources include eggs, milk, yogurt and cheese. These foods provide between 10 and 19 percent of the RDA of vitamin B-12 per serving. Foods that have 20 percent or more of the vitamin's RDA in every serving are considered excellent sources and include 3 ounces of clams, 3 ounces of beef, 1 cup of vitamin-fortified breakfast cereal or 3 ounces of fish, such as salmon, trout, tuna or haddock.