Their conclusion rests on strong evidence that a raised homocysteine concentration is a cause of cardiovascular disease. Homocysteine can be lowered by folic acid.
Over 100 studies on the association between serum homocysteine and cardiovascular disease were analysed. Some looked at the prevalence of a genetic mutation, which increases homocysteine (genetic studies), and some looked at homocysteine and disease risk (prospective studies).
The genetic studies and the prospective studies did not share the same potential sources of error but both yielded similar results - strong evidence that the association between homocysteine and cardiovascular disease is causal. On this basis, the researchers estimate that folic acid could reduce the risk of ischaemic heart disease by 16%, deep vein thrombosis by 25%, and stroke by 24%.
The folic acid could be taken as tablets by people at high risk (those with existing cardiovascular disease or anyone above age 55), or possibly supplied to the general public through food fortification or a combination of both, as a simple and safe means of prevention, they conclude.
Folic acid food fortification has already been introduced in America to prevent the birth defect spina bifida. This research shows that such fortification will also help prevent heart attacks and strokes.