By Anthony J. Brown, MD
NEW YORK (Reuters Health) – A group of Irish researchers recommends that, in order to improve vascular health by lowering homocysteine levels, food should be fortified with vitamin B12 as well as folic acid.
Apart from its benefit in reducing neural tube birth defects, consumption of folate-fortified foods is known to cause a reduction in plasma levels of total homocysteine. However, a report in the January 19th issue of The Lancet shows that once a certain folate level is reached, vitamin B12 has an important lowering effect on homocysteine levels.
Dr. Joe McPartlin, from St. James's Hospital in Dublin, Ireland, and colleagues assessed the effects of folate supplementation in 30 men and in 23 women. The subjects received increasing doses of folate over a 26-week period.
Serum folate levels were inversely related to serum homocysteine levels. Initially, vitamin B12 levels showed a weak inverse relationship with homocysteine levels. However, "as the people became saturated with folic acid, vitamin B12 became the main determinant of homocysteine levels," Dr. McPartlin told Reuters Health.
"The take-away message is that you can only lower homocysteine levels so much by taking folic acid," Dr. McPartlin stated. "After that, it depends on the person's vitamin B12 status," he added.
The investigators say the findings have implications for countries considering a food fortification policy.
"Co-fortifying with vitamin B12 has two possible benefits," Dr. McPartlin emphasized. "First, it enhances the reduction in homocysteine levels," he said. "Second, which we have previously shown, it appears to further decrease a woman's risk of having a baby with neural tube defects."