B Vitamins May Not Cut Heart Risks
In High-Risk Patients Taking B Vitamin Supplements, Heart Risks Remain
The second study was the Norwegian Vitamin (NORVIT) trial. The researchers included Kaare Harald Bonaa, MD, PhD, of the University of Tromso in Tromso, Norway.
The NORVIT trial included 3,749 men and women who had had a heart attack up to a week before joining the study. The researchers randomly assigned patients to take one capsule per day containing one of four treatments:
- 0.8 milligrams of folic acid, 0.4 milligrams vitamin of B-12, 40 milligrams of vitamin B-6
- 0.8 milligrams of folic acid, 0.4 milligrams of vitamin B-12
- 40 milligrams of vitamin B-6
Over an average of three years, blood homocysteine levels fell 27%, on average, for patients given folic acid and vitamin B-12.
But none of the vitamin groups cut their risk of major cardiovascular "events," the researchers write. Those "events" were fatal or nonfatal heart attack, fatal or nonfatal stroke, and sudden death attributed to heart disease.
The HOPE 2 researchers noticed that in the vitamin group, fewer patients had strokes but more were hospitalized for unstable angina (chest pain). The stroke findings may have been due to chance, and the reasons for the increase in hospitalizations for unstable angina in the vitamin group aren't clear, the researchers note.
The NORVIT trial also showed an unexpected "trend toward an increased rate of events among patients receiving B vitamins, in particular the combination of folic acid, vitamin B6, and vitamin B12," write Bomaa and colleagues.
Bonaa's team can't rule out the possibility that that trend was due to chance, not the vitamins.
Both studies included a series of lab tests showing that the vitamin takers boosted their levels of the B vitamins. Compliance with the treatments appeared to be good, the studies show.
The HOPE 2 and NORVIT studies show no clear heart benefits with any of the B vitamins that were studied.
"Supplements combining folic acid and vitamins B6 and B12 did not reduce the risk of major cardiovascular events in patients with vascular disease," write Lonn and colleagues for the HOPE 2 study.