- Health A to Z
In brief
It seems to make sense. Folic acid (the artificial form of folate), in combination with vitamins B6 and B12, lowers levels of homocysteine, an amino acid in the blood. Dozens of studies have shown that people with high levels of homocysteine are more likely to have heart attacks and other problems associated with diseased and clogged coronary arteries. It’s not completely understood why, but too much homocysteine swirling through the bloodstream may promote the growth of unhealthy tissue inside the arteries and also make blood more likely to clot.
One of the main problems in using angioplasty to reopen blocked coronary arteries has been restenosis, the tendency of the opened artery to close up again. So wouldn’t people who’ve had angioplasty benefit from taking vitamins that lower homocysteine?
Three years ago, results from the Swiss Heart Study suggested that, yes, they would. The angioplasty patients assigned to “folate therapy” — shorthand for the folic acid-vitamin B6-vitamin B12 combo — needed fewer repeat angioplasties and had less restenosis than those assigned to take a placebo.
So far, so good (and so inexpensive). But a Dutch study has contradicted the Swiss one. The 600-person, placebo-controlled trial found that folate therapy increased both the need for repeat operations and the rate of restenosis. The study, published earlier in 2004 in the New England Journal of Medicine, was partially funded by Medice, a German company that makes vitamin pills.
How can two well-designed studies of the same issue come to such opposite conclusions? One explanation: The folate therapy in the Dutch study included a much larger dose of vitamin B6 (48 milligrams versus 10 milligrams). Such a large dose may change how homocysteine is metabolized and how it affects blood vessels.
More significantly, perhaps, all of the patients in the Dutch study were treated with stents, tiny wire-mesh tubes inserted into narrowed arteries to keep them open. Most angioplasty is done with stents. The factors that cause restenosis, including homocysteine, may be different with a stent.
Besides, the two studies aren’t as contradictory as their overall conclusions might suggest. In the Dutch study, the vitamin combo did lower the restenosis rates for some people, including women, diabetics, and those with very high homocysteine levels.
As an editorial in the New England Journal of Medicine pointed out, people who’ve had angioplasty are often ready to make changes in their lifestyle. They’ve had a major scare. Even if there’s some question about vitamins, post-angioplasty is a prime time to get serious about other things that can protect the heart and health: losing weight, quitting smoking, and exercising.