DUBLIN, IRELAND. Since 1998 it has been mandatory to fortify grain-based foods with folic acid in the United States. Recent reports indicate that this measure has resulted in a 19 per cent decrease in the incidence of neural tube defects. A similar fortification program is being considered in the UK. Irish researchers now suggest that the fortification protocol should include not only folic acid, but also vitamin B12. They point out that folic acid supplementation also lowers the level of homocysteine, a potent risk factor for heart and vascular disease. However, a recent trial carried out by the Dublin researchers clearly showed that as blood levels of folic acid increased through supplementation, blood levels of vitamin B12 became the limiting factor. In other words, additional folic acid as well as additional vitamin B12 is required in order to attain the maximum reduction in homocysteine levels. Four to five hundred micrograms per day of folic acid were found to increase folic acid levels by 80 to 180 per cent and lower homocysteine levels by about 30 per cent in both men and women. Both folate and homocysteine levels tended to revert to their pre-supplementation levels after 10 weeks of no supplementation; this shows that continuous supplementation is necessary in order to keep homocysteine levels under control.
Quinlivan, E.P., et al. Importance of both folic acid and vitamin B12 in reduction of risk of vascular disease. The Lancet, Vol. 359, January 19, 2002, pp. 227-28 (research letter)