by Mitchell Clute
A Norwegian study on vitamin B and coronary disease has been roundly criticized for criteria and design. The study, released last September but published this month in the Journal of the American Medical Association, concluded that B vitamin supplementation does not reduce the risk of cardiovascular events or death.
The study, conducted during a seven-year span, analyzed 3,096 patients with heart problems in two Norwegian hospitals, and concluded that there was no statistical difference between those taking B vitamins and those taking placebos.
"This study isn't related to a healthy population in any way, shape or form," said Daniel Fabricant, Ph.D, vice president of scientific and regulatory affairs for the trade group Natural Products Association, based in Washington, D.C. "A large percentage of participants were taking other medications for cardiovascular disease, for example, but there's no indication of whether or not they continued these medications throughout the study."
At the start of the study, 78 percent of subjects were concomitantly taking beta blockers, and 88 percent were taking beta blockers, but the study, as published, doesn't mention whether these treatments were taken throughout the research period. In addition, though participants were asked if they already took a B vitamin supplement, they were not asked about multi-vitamin intake, and the study authors did not control food intake for folic acid, B6 or B12.
"The news media got a hold of this story and said that B vitamins don't help with cardiovascular disease," Fabricant said. "It was reported as if we knew all the factors, and that's just not the case. Whenever a provocative story like this gets media attention, people beat their drums, but the rule of thumb is that one study is never conclusive. I would advise people to look at the whole body of evidence."
In fact, there is evidence that contradicts this study's findings. For example, a study conducted in Japan and published earlier this year in the Journal of the American College of Nutrition looked at people who were between 40 and 59 years of age and free of existing heart disease or cancer at the start of the study. Looking at more than 40,000 subjects during a nine-year period, the study found that intake of B6, B12 and folate found that all these supplements, but particularly B6, had a mitigating effect on the development of cardiovascular disease.
Andrew Shao, Ph.D., of the Council for Responsible Nutrition, said in a statement, "This study, like other similarly designed studies, fails to answer the question of whether B vitamin supplementation, over the long-term, can help reduce the risk of cardiovascular disease in a population that is healthy at baseline."