The role of raised total plasma homocysteine concentrations and cardiovascular disease is not proving to be as clear cut as originally hoped. Whilst raised total plasma homocysteine concentrations are associated with cardiovascular disease in observational studies, clinical trials have not realised these expectations, raising the possibility that raised total plasma homocysteine concentrations are innocent bystanders.
Several large trials using folic acid to lower raised total plasma homocysteine concentrations have failed to improve cardiovascular disease and when folic acid is added to vitamin B supplements may even accelerate risks.
The Lancet ( June 2nd 2007 volume 369, )reports a meta analysis study and a comment on the role of raised total plasma homocysteine concentrations, folic acid supplementation and stroke incidence. Wang and colleagues have undertaken a meta analysis of the various trials and found a modest benefit from the use of folic acid supplements. The comment is somewhat less enthusiastic pointing out the complexity of such studies which can be complicated by the addition of folic acid to food.
Whatever the final decision for the use of folic acid and the reduction of raised total plasma homocysteine concentrations and benefits for cardio vascular disease it may not prove to be as great a benefit as originally hoped for.
Carlsson 2007, Lowering homocysteine for stroke prevention Lancet vol 369, pp1841-2
Wang et al 2007 Efficacy of folic acid supplementation in stroke prevention: a meta analysis Lancet vol 369, pp 1876-82
- Martin Eastwood