That's according to a new study from Norway published in The Journal of the American Medical Association.
The study shows that coronary artery disease patients taking cardiovascular drugs didn't cut their risk of death, nonfatal heart attack or clot-related stroke, or other problems by taking folic acid, vitamin B12, and/or vitamin B6 supplements for about three years.
This isn't the first study to come to that conclusion, and even the Council for Responsible Nutrition, a trade group for the dietary supplement industry, doesn't question the latest findings. But the council argues that the results may not apply to people with healthy hearts.
Heart Disease and B Vitamins
The new study included more than 3,000 heart disease patients in Norway, where folic acid isn't added to wheat as it is in the U.S.
The patients kept taking those drugs during the study. They were also randomly assigned to either take folic acid plus vitamins B6 and B12, folic acid plus vitamin B12, vitamin B6 alone, or a placebo pill -- without knowing which group they were in.
During the study, which lasted for just over three years, the patients got periodic blood tests to measure their level of homocysteine, which is an inflammatory chemical linked to higher rates of heart disease.
The researchers expected homocysteine levels to drop in the folic acid groups. The key question was what difference that would make to the patients' heart health. The short answer: Homocysteine levels fell as predicted, but it didn't matter much.
No Support for B Vitamins
Over the course of the trial, the patients taking folic acid and vitamin B12 had the biggest drop in their homocysteine level, which wound up 26% lower than patients who weren't taking folic acid.
But even those patients weren't less likely to die of any cause, suffer a nonfatal heart attack or clot-related stroke, be hospitalized due to unstable angina (chest pain), or need to have a narrowed or blocked coronary artery surgically reopened.
Those "events" happened to similar percentages of patients -- ranging from 12% to 16% -- in each group. The differences in those percentages were so small that they may have been due to chance.
"Our findings do not support the use of B vitamins as secondary prevention in patients with coronary artery disease," write the researchers, who included Marta Ebbing, MD, of Norway's Haukeland University Hospital.
What About Healthy People?
The results "were not particularly surprising," Andrew Shao, PhD, vice president for scientific and regulatory affairs at the Council for Responsible Nutrition, tells WebMD.
Noting that several other trials in recent years have reached the same conclusions, Shao says "it appears to be consistent that [for] subjects who have underlying cardiovascular disease and [are] on multiple medications ... adding B vitamins on top of a whole host of other medications doesn't appear to provide any further benefit."
But Shao says similar trials haven't been done in healthy people to see if B vitamins help prevent heart disease from happening in the first place. Such trials aren't likely to happen, says Shao, because they would need to last decades and include hundreds of thousands of people. "Unfortunately, they're logistically impossible and cost-prohibitive."
Shao points to observational studies that show that people with higher homocysteine levels "are at much higher risk for cardiovascular disease." He acknowledges that observational trials don't prove cause and effect -- that is, they don't show whether homocysteine causes heart disease or rides along with heart disease without instigating it.
"That's an inherent limitation" of observational studies, says Shao, adding that the Norwegian study is limited because "it applies only to a very narrow section of the population. It doesn't answer the question that we're all interested in," which is what is the effect of B vitamin supplements in healthy people.