Eat Your Heart Out

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This same sort of blood-vessel inflammation, doctors believe, may be triggered by bacterial and viral infections. Chlamydia (which generally starts as a venereal disease) and gingivitis (an infection of the gums) have both been implicated in heart disease, and more recently so has the herpesvirus that causes cold sores. In the case of herpes, especially, it's far too early to tell whether this link is real or will evaporate under closer scrutiny.

Alcohol
It's known as the French paradox: people who live in France eat huge quantities of saturated fat (in the form of butter, cheese and other milk products), yet they have one of the lowest rates of cardiovascular disease in the world. One compelling explanation is that the French also drink wine, usually in moderation. Too much alcohol can destroy just about every organ in the body, the heart included. But investigators have discovered through clinical trials that people who take an occasional nip have about a 20% lower risk of heart disease than do teetotalers.

The mechanism isn't entirely clear, but alcohol may boost blood levels of HDL, the good cholesterol that cleans plaque off arterial walls. Two to four drinks a week seem optimal for men, one to three for women. Since excess alcohol consumption is the second leading cause of preventable death in the U.S., says Dr. Charles Hennekens of Harvard Medical School, "I'm opposed to a wide public health recommendation to drink alcohol. But I'm ready to consider it for a particular patient after going over his or her risks and benefits."

Homocysteine
Victims of the rare genetic disorder known as homocystinuria usually die by age 20 from heart attack or stroke. They also have high blood levels of the amino acid homocysteine, a by-product of protein metabolism. That's highly suggestive of a cause-and-effect relationship, but after decades of investigation, the link between homocysteine and heart disease is still elusive. Says Dr. Andrew Bostom, co-director of the Cardiac Rehabilitative program at Memorial Hospital in Pawtucket, R.I.: "We have tantalizing suggestions that we might actually be dealing with a real risk factor, but we don't have smoking-gun evidence."

They do, however, have a plausible explanation for how homocysteine possibly works. If too much circulates in the blood, researchers believe, it may combine with LDL to form large molecules that are especially likely to attract the immune-system cells that help form plaques.

The good thing about homocysteine is that if it does prove to be a significant cause of heart disease, the treatment is in hand: studies have consistently shown that homocysteine can be easily controlled with B vitamins and folic acid, either in the diet or in supplements. The most recent study appeared two months ago in the New England Journal of Medicine: a government requirement that all flour, pasta and other grain products manufactured after Jan. 1, 1998, be enriched with folic acid (to stave off spinal-cord defects in newborns) has already measurably reduced homocysteine levels across the board.

New risk factors identified, old risks reassessed, varying degrees of uncertainty about every medical study ever published--it all seems so confusing, you may be tempted just to throw a steak on the grill, butter your baked potato and forget the whole thing.

But that would reflect a misunderstanding about how science works. It is not a steady march from ignorance to knowledge. It's more like a mountaineering expedition. On the way up an unscaled peak, climbers will gain some altitude on one route, then find it's a dead end. They'll spot a better one, backtrack a little and move on. The fact that they sometimes have to take a step backward for every two steps forward doesn't mean they're wasting their time. It means that inching up an uncharted mountain is tough work.