A study in the Journal of the American Medical Association reports that heart attack patients who lowered their blood homocysteine levels with folic acid and vitamin B12 did not experience lower risk of heart attack, stroke or coronary death. The risk of cancer did not increase however.
Cardiovascular disease is linked with blood homocysteine levels. Daily supplementation of folic acid and vitamin B12 was seen to lower homocysteine levels.
" 'Taken together with the previous homocysteine-lowering trials, the results of SEARCH indicate that folic acid supplementation has no significant adverse effects on cancer or other major health outcomes, even if it also produces no beneficial effects on cardiovascular disease. In addition, these results highlight the importance of focusing on drug treatments (e.g., 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,' the authors conclude."
http://www.medicalnewstoday.com/articles/194449.php