Vitamin B May Do More Harm Then Good For Heart Disease and Homocysteine

High-dose vitamin B may do more harm than good for heart disease, and homocysteine, billed as a heart disease risk factor, isn’t one after all, researchers reported.

"The homocysteine hypothesis is dead," declared Kaare Bonaa, M.D., of the University of Tromso in Trondheim, Norway. In terms of heart disease risk, "homocysteine is an innocent bystander," he said.

And that wasn’t the only bad news for believers in simple helpers in heart disease and prevention. Fish oil capsules did not reduce cardiac events in patients with implanted cardioverter defibrillators (ICDs), a team of Dutch researchers reported.

In the vitamin B-homocysteine arena, Dr. Bonaa and colleagues enrolled 3,749 myocardial infarction patients in the Norwegian Vitamin Trial (NORVIT). Patients were randomized to high dose vitamin B, high dose folic acid, or placebo for up to three years.

As expected the high doses of vitamin B lowered circulating homocysteine by 30%, but rather than decreasing heart attack risk, "there was a 20% increase in risk of cardiovascular events," Dr. Bonaa said.

In the past high levels of homocysteine have been associated with heart disease, but attempts to treat the patients by lowering levels of the hormone, especially with folic acid and other B vitamins, have had disappointing outcomes.

In NORVIT, the participants took doses of 40 mg of Vitamin B-6 or 0.8 mg of folic acid per day. Dr. Bonaa said that the doses are prescribed at that level in Europe and represent two tablets of the vitamins that are sold over-the-counter in the United States. He said that the risk of suffering heart attacks or strokes was no different if the patient was taking either vitamin or placebo. However, patients taking both vitamins had about a 20% increased risk of having a heart attack or stroke (P=0.029).

In addition there was a non-significant trend for an increased risk of cancer among those on the high doses of vitamins.

"The results of the NORVIT trial are important because they tell doctors that prescribing high doses of B vitamins will not prevent heart disease or stroke," Dr. Bonaa said. "B vitamins should be prescribed only to patients who have B-vitamin deficiency diseases." He noted that in the trial measurements of homocysteine were made before and during treatment and showed that the vitamins dramatically reduced levels of homocysteine. However, the lowering effect did not translate into a clinical benefit.

Raymond Gibbons M.D., professor of medicine at the Mayo Clinic, who is president-elect of the American Heart Association, said that in addition to possible harm that could occur to the person taking such substances as vitamins, taking the substances "wastes resources and most patients can only take so many pills." Moreover, he boasted that in his career in cardiology, he has "never ordered a homocysteine test."

But others said it is too early to count out either vitamin B or homocysteine. For example, Lampros Michalis, M.D., of the University of Ioannina, Greece, who moderated a press conference where the study was discussed, said "every time we have tried to find a connection between homocysteine and lowering it with vitamins we never find anything. But it [homocysteine] is so appealing that a natural substance such as a vitamin that can reduce homocysteine levels that investigators will again try to see if there is a connection."

These studies were published as an abstract and presented orally as late-breaking reports at a conference. These data and conclusions should be considered to be preliminary as they have not yet been reviewed and published in a peer-reviewed publication. Presented at the European Society of Cardiology Congress 2005.

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