Taking a supplement with both folic acid and vitamin B12 lowers homocysteine levels more dramatically than taking folic acid alone. Homocysteine is an amino acid that has been associated with a greater risk of heart disease. Previous studies have indicated that folic acid can lower homocysteine levels. Although it has not been proven that lowering homocysteine level can prevent heart problems, the American Heart Association issued an advisory this week suggesting that those with a history of heart disease make sure that they consume the recommended daily allowance (RDA) of vitamin B6, vitamin B12, and folic acid. And because adequate folic acid intake during pregnancy can reduce the risk of certain birth defects, namely neural tube defects, the US Food and Drug Administration ruled that all grain and grain products should be fortified with folic acid as of January 1, 1998.
American Journal of Clinical Nutrition 1998;68:1104-1110.
COMMENT: I was surprised to see that this report actually showed benefit from oral B12. Vitamin B12 is the largest of all the vitamins and is very difficult for many people to absorb orally. This is due to a loss of a substance produced by the stomach cells called intrinsic factor. This is the reason why B12 is generally given by injection as this improves absorption dramatically. Generally, under the tongue, or sublingual, doses are more effective than oral doses, but even once daily sublingual doses would take one full month of treatment to provide similar benefit to one injection of B12. B12 is about as safe as water and I am not aware of any toxicity which is why I normally recommend daily treatment for one week and then two to three times a week treatment for those who need this vitamin supplement. It is important to consider supplementing with vitamin B12 when one takes folic acid as folic acid can mask the potential neurological complications of B12 deficiency by normalizing the anemia one observes with B12 deficiency. Vegetarians and the elderly are particularly sensitive to this complication.