Long-term homocysteine reduction may not improve vascular outcome
MedWire News: Lowering homocysteine levels with folic acid and vitamin B12 supplementation does not improve the vascular outcomes of patients after myocardial infarction (MI), UK researchers report.
Previous studies have identified an association between high blood homocysteine levels and occlusive vascular disease, therefore suggesting a possible benefit of lowering levels with folic acid or vitamin B12.
In the Journal of the American Medical Association, Jane Armitage (University of Oxford) and colleagues explain: “Daily supplementation with folic acid typically lowers homocysteine levels by about 25%, and the addition of vitamin B12 lowers it by a further 7%. Folic acid is inexpensive so there is considerable interest in the possibility of reducing the incidence of occlusive vascular disease with folic acid supplementation.”
To investigate, the team recruited 12,064 male (n=10012) and female (n=2052) MI patients between September 1998 and June 2008. The patients were aged between 18 and 80 years and were randomly assigned to receive a tablet containing 2 mg folic acid and 1 mg vitamin B12 (n=6033) or a placebo tablet(n=6031) daily.
During the mean follow-up period of 6.7 years, the patients who received folic acid plus vitamin B12 experienced a mean 3.8-µmol reduction in blood homocysteine levels compared with those who received placebo.
However, folic acid and vitamin B12 supplementation did not appear to protect against a first major coronary event (coronary death, MI, or coronary revascularization), fatal or non fatal stroke, or non-coronary revascularization.
For each outcome, the rates did not differ significantly between patients taking the folic acid and vitamin B12 supplement and those taking placebo, at a respective 19.6% and 20.4% for a major coronary event, 4.4% and 4.5% for stroke of any type, and 2.5% and 3.0% for non-coronary revascularizations
There was also no difference in vascular and non-vascular mortality rates between the two groups.
Although the long-term reduction of blood homocysteine levels with folic acid and vitamin B12 supplementation did not have a beneficial effect on vascular disease outcomes, the team reports that it did not have an adverse effect on cancer incidence as previous reports have suggested.
The team concludes: “These results highlight the importance of focusing on drug treatments (aspirin, statins, and antihypertensive therapy) and lifestyle changes (in particular, stopping smoking and avoiding excessive weight gain) that are of proven benefit, rather than lowering homocysteine with folic-acid based vitamin supplements, for the prevention of cardiovascular disease.”
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010
By Lauretta Ihonor