Researchers from Norway have found that treating patients who have had a heart attack with high doses of B vitamins does not lower the risk of getting another heart attack or stroke. Contrary to expectations, B vitamins may do more harm than good.
These surprising data were presented at the Hot Line Session II of the European Society of Cardiology Congress in Stockholm on 5th September 2005.
NORVIT, the Norwegian Vitamin Trial, is the first trial to examine whether high doses of B vitamins prevent recurrent heart disease in patients who have had a myocardial infarction. A total of 3749 patients were recruited from 35 Norwegian hospitals. The patients were assigned to take B vitamins or placebo for more than three years in addition to standard treatments after a heart attack.
Professor Kaare Harald Bønaa MD, University of Tromsø, Norway, principal investigator of the NORVIT trial, comments, "The results of the NORVIT trial are important because they tell doctors that prescribing high doses of B vitamins will not prevent heart disease or stroke. B vitamins should be prescribed only to patients who have B vitamin deficiency diseases."
The participants in the NORVIT trial were divided at random into four groups that received either 0.8 mg folic acid (a B vitamin) per day, 40 mg vitamin B-6 per day, both 0.8 mg folic acid and 40 mg vitamin B-6 per day, or a placebo capsule per day. Those who took folic acid or vitamin B-6 alone had a small increase in the risk of cardiovascular disease. However, among those who took both vitamins the risk increased by 20 percent.
During the last 15 years interest in vitamin B research has rocketed worldwide because studies indicated that folic acid and vitamin B-6 could prevent heart disease and stroke. Researchers have believed that this was due to the ability of B vitamins to lower the blood level of an amino acid called homocysteine. It was thought that high levels of homocysteine may damage the lining of arteries and increase clotting of the blood. This can cause fatal blockages of arteries in the heart and brain.
"Some doctors have found the previous data so compelling that they have already started to treat patients with B vitamins to lower the homocysteine level. However, in the NORVIT trial, homocysteine levels were lowered by 30%, but this did not lower the patients' risk of cardiovascular disease", said Kaare Harald Bønaa MD.