Is The Recommended Daily Allowance For Vitamin B12 1000 Mcg?

Vitamin B12 is one of nine members of a family of water-soluble compounds known as the B-complex vitamins. The B-complex vitamins primarily function as coenzymes for carbohydrate, fat and protein metabolism. Vitamin B12 serves several specific functions in the human body, although most individuals need very small amounts of this substance each day. The Food and Nutrition Board of the Institute of Medicine provides recommended dietary allowance, or RDA, values for all vitamins, including vitamin B12.

Vitamin B12 Recommendations

The RDA for vitamin B12 for males and females ages 19 and older is 2.4 mcg a day. Males and females ages 9 to 13 should consume 1.8 mcg of vitamin B12, while male and female children ages 1 to 3 and 4 to 8 should consume 0.9 and 1.2 mcg each day, respectively. Pregnant and nursing mothers have slightly higher RDAs, at 2.6 and 2.8 mcg a day, respectively. Elderly populations sometimes have difficulty absorbing food sources of vitamin B12, so the IOM recommends adults over the age of 50 consume a vitamin B12 supplement.

Specific Functions

According to "Essentials of Exercise Physiology," vitamin B12's primary function is as a coenzyme in nucleic acid metabolism. Like other B vitamins, vitamin B12 assists with nutrient metabolism, promotes the formation of red blood cells and helps maintain central nervous system function.

Sources

Vitamin B12 exists strictly in animal products. Common sources of vitamin B12 include meat, eggs, dairy products, fish and seafood, poultry and fortified products such as cereal and soy milk. According to the USDA Nutrient List, beef is the highest source of vitamin B12 per serving, followed by mollusks, turkey, chicken and pork sausage.

Deficiency

Because vitamin B12 is a water-soluble vitamin and needs to be consistently replenished in the diet, side effects of deficiency, or intake less than 50 percent of one's RDA, can occur in as little as four weeks, according to "Essentials of Exercise Physiology." Vitamin B12 deficiency has been known to result in pernicious anemia, a red blood cell disease in which the body can no longer absorb the vitamin, ultimately resulting in compromised red blood cell production. Vitamin B12 deficiency may also result in neurological disorders such as spinal cord degeneration and multiple sclerosis.