Vitamin B12 is a member of the B-complex group of vitamins. Micro-organisms such as bacteria, yeast and molds are the only true source of this vitamin, although many animal products contain it as a result of the healthy bacteria that animals harbor. The recommended daily intake of vitamin B12 depends on the age of the individual. Special circumstances like pregnancy or disease may affect the need for additional vitamin B12.
Importance
One major function of vitamin B12 is to assist in the formation of new red blood cells. Vitamin B12 also operates in the synthesis of DNA. Another function of this nutrient is to support the growth and development of the myelin sheath of neurons in the brain. It also aids in the cellular processing of fats, carbohydrates and protein.
Recommendations
According to the NIH Office of Dietary Supplements, both male and female individuals over 14 years of age should consume 2.4mcg of vitamin B12 every day. Preteens between the ages of 9 and 13 should get a minimum of 1.8mcg daily. The recommended daily intake for children between 4 and 8 is 1.2mcg. Children between 1 and 3 need 0.9mcg every day. Babies under the age of 1 typically get enough vitamin B12 through breast milk or formula, about 0.5mcg every day when between 7 months and 1 year old and 0.4mcg for babies 6 months and younger.
Special Circumstances
Pregnant women should take 2.6mcg daily, and lactating mothers should consume a minimum of 2.8mcg every day. Individuals with low stomach acid, pernicious anemia or intestinal disorders may have difficulty absorbing vitamin B12 and may need to take more of this vitamin to ensure adequate levels. Vegetarians may not get enough vitamin B12 in the diet, since plant foods contain little of this nutrient. Many vegetarians take vitamin supplements to make up for the lack of vitamin B12 in their diets.
Sources
Vitamin B12 occurs naturally in meat, poultry, fish, milk, dairy products and eggs. Ready-to-eat breakfast cereals are often fortified with vitamin B12, often containing either 25 percent or 100 percent of the daily recommended intake in a single serving of cereal. Vitamin B12 may also be included as part of a multivitamin or taken as individual supplements, but the bioavailability of vitamin B12 in supplement form is much lower than when it is consumed in whole foods.
Considerations
Vitamin B12 is considered to have low toxicity, with no negative effects associated with high doses. Consequently, no maximum upper limit has been established for this vitamin. Individuals taking certain medications, including H2 receptor antagonists, proton pump inhibitors, metaformin, birth-control pills and certain antibiotics, may need to limit their vitamin B12 intake since this vitamin can interact with these medications.
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