WEDNESDAY, June 23, 2004 (HealthDayNews) -- The role of folate and vitamin supplements in keeping arteries clear of fatty deposits has been questioned by a study showing that they increase the risk of complications for some patients who have coronary procedures.
The risk of arteries closing again after the implantation of vessel-widening tubes called stents was higher in patients who got the supplements than in those who didn't, said a report by European researchers in the June 24 issue of the New England Journal of Medicine.
It's a very complicated issue, since the newly reported study conflicts sharply with an earlier Swiss study showing that the supplements reduced the risk that arteries would close, noted Dr. Harry Suryapranata, a cardiologist at the De Weezenlanden Hospital in the Netherlands and a member of the research team.
The new study did show benefits of the supplements for some patients, such as women and those with diabetes, Suryapranata said. But the two studies also differed in several ways, including the dosage of the supplements, so many questions remain unanswered, he said.
"Two randomized trials would never be conclusive on any issue," Suryapranata said. "Therefore, further trials are certainly needed."
But recent medical progress may have already weakened the significance of the two studies, said Dr. Howard C. Herrmann, director of interventional cardiology at the University of Pennsylvania, who wrote an accompanying editorial.
The European study was done when only bare-metal stents were available, Herrmann pointed out. Now cardiologists use drug-releasing stents, which are coated with medications that help prevent restenosis, the medical term for the subsequent closing of arteries.
"To most interventionalists, it isn't a big issue any more," Herrmann said. "The problem of restenosis has been solved by coated stents."
The new issue is whether folate and vitamin supplements are appropriate for patients with high blood levels of the amino acid homocysteine, which some studies have linked to an increased risk of heart attack and stroke. Those supplements can reduce homocysteine levels.
"Folate supplementation has always been considered a completely safe therapy," Herrmann said. "Now the argument is on a higher level, because we have a study which suggests possible harm. We have to be careful about which patients use it."
Folate supplements appear to be appropriate for "a small portion of the population of patients with atherosclerosis," the formal name for the process that can end with blockage of an artery, Herrmann said.
For example, folate supplements might be useful for patients who do not respond well to statins, the widely used cholesterol-lowering drugs, he said. In general, he believes folate supplements are "a good thing to try" for patients who have high blood levels of homocysteine but not other risk factors such as high blood pressure.
The rhyme and reason of folate supplementation is explained by the National Institutes of Health.