form neurotransmitters in the brain, such as serotonin, that help regulate mood, sleep, and appetite
Information The recommended dietary intake, or RDI, for vitamin B12 for adults is 2 micrograms (mcg) per day. For pregnant women, the RDI is 3 mcg; for nursing women it is 2.5 mcg. A microgram is a very small amount. Since the only dietary sources of B12 are animal products, strict vegetarians may need to take supplements. They may also eat foods that have had the vitamin added.
Not getting enough vitamin B12 can cause:
anaemia
fatigue
nerve damage, with symptoms such as tingling sensations and numbness
sore tongue
very sensitive skin
muscle and nerve paralysis
constipation
Some people have trouble absorbing B12. Other people may just have poor dietary intake. Anaemia can be treated with injections of B12. Strict vegetarians who eat no animal products, their infants, and older people are at the highest risk for vitamin B12 deficiency. For these people, eating fortified foods and/or taking dietary supplements can help prevent a deficiency. High intakes of folic acid can hide anaemia.
Getting too much vitamin B12 has no known symptoms or toxicity. It is stored mainly in the liver. Since it is water-soluble, any extra leaves the body in the urine. There is no proof that taking extra B12 boosts energy. Vitamins do not create energy. They do not provide kilojoules to the body for energy. Vitamins help breakdown nutrients that are energy-yielding. These nutrients include carbohydrate, protein, and fat.
Calcium is necessary for normal absorption of vitamin B12. A deficiency of either iron or vitamin B6 can decrease the absorption of B12.
Author: Kimberly Tessmer, RD, LD Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
