Patients with heart disease in Norway, a country with no fortification of foods with folic acid, had an associated increased risk of cancer and death from any cause if they had received treatment with folic acid and vitamin B12, according to a study in the November 18 issue of JAMA.

Most epidemiological studies have found inverse associations between folate (a B vitamin) intake and risk of colorectal cancer, although such associations have been inconsistent or absent for other cancers, according to background information in the article. "Experimental evidence suggests that folate deficiency may promote initial stages of carcinogenesis, whereas high doses of folic acid may enhance growth of cancer cells. Since 1998, many countries, including the United States, have implemented mandatory folic acid fortification of flour and grain products to reduce the risk of neural-tube birth defects," the authors write. "Recently, concerns have emerged about the safety of folic acid, in particular with respect to cancer risk."

B vitamins are essential nutrients for growth, development and numerous bodily functions. They play a major role in the breakdown of carbohydrates into glucose, providing energy for the body, as well as the breakdown of fats and proteins, which aids the normal functioning of the nervous system. However, while B vitamins are needed to help avoid many health conditions, cancer doesn’t appear to be one of them, as some previous research had suggested.

Vitamin B₁₂ (cobalamin) functions as a coenzyme for a critical methyl transfer reaction that converts homocysteine to methionine and for a separate reaction that converts L-methylmalonyl-coenzyme A (CoA) to succinyl-CoA. The Recommended Dietary Allowance (RDA) for vitamin B₁₂ is based on the amount needed for the maintenance of hematological status and normal serum vitamin B₁₂ values. An assumed absorption of 50 percent is included in the recommended intake. The RDA for adults is 2.4 µg/ day of vitamin B₁₂.