Medical Journals, B Vitamins, and Cardiovascular Disease

Most medical journals claim to publish “peer-reviewed” articles, implying that the research has passed the muster of qualified physicians or researchers. In practice, many journal articles lack any substantial critical analysis before publication. 
I believe this is one reason why so much poor-quality research, especially research critical of nutritional therapies, finds its way into print. Then, once in print, this junk science becomes an urban gospel – repeated in the form of poor advice to patients and in newspaper articles. The real peer review occurs after publication, often months later as letters to the editor, and without any newspaper headlines. Consider the following study as an example.

Earlier this year, researchers from the Harvard Medical School published a study in JAMA (Journal of the American Medical Association) in which female health professionals took either B-complex vitamins or placebos for an average of 7.3 years. The vitamin supplements lowered levels of homocysteine – a risk factor for cardiovascular diseases – but did not seem to reduce the risk of cardiovascular disease.

The study was touted as proof that B vitamins were worthless when it came to lowering the risk of heart disease and stroke. But four months later, in letters to the editor of JAMA, other physicians pointed out what should have been obvious early on: the study’s subjects, who were doctors and other medical professionals, were unlikely to be deficient in folic acid. In fact, the blood levels of the vitamin were normal in more than two-thirds of the subjects, meaning that they were less likely to benefit from supplements.

The original researchers acknowledged the critics’ comments and responded in part by writing that the folic acids’ lack of benefit “may not apply to populations with a greater prevalence of folate deficiency.” So, the vitamin might work after all.

The body’s use of folic acid is strongly influenced by genetics. Some genetic variations – an important variable – increase individual requirements for folic acid. These genetic variations were not assessed in this study, so it is very possible that folic acid supplements did benefit some people, but not others.