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Everything You Know Is Wrong 03 ( By TIMEasia - Sep. 6. 1999 )

PHYTOCHEMICALS

Adding fruits and vegetables to the diet is good for the heart in many ways. It displaces meat and dairy products and thus reduces the intake of saturated fats. It puts more vitamins--not just E but also C and many of the B vitamins--into your body.

Over the past several years, however, researchers have been investigating a whole new class of plant-based substances whose role in preventing heart disease may be even more important than vitamins. Known as phytochemicals, they fall into two classes: carotenoids, found mostly in orange-colored vegetables (beta carotene is the best known of the more than 600 carotenoids); and flavonoids--some 4,000 of them, found in, among other things, onions, broccoli, red wine and tea (green, black and oolong, but not herbal).

Like vitamin E, the flavonoids and the carotenoids appear to act as antioxidants, keeping LDL and triglycerides from being oxidized by free radicals. But they do so in different ways, explains Jeffrey Blumberg, a Tufts University nutritionist: "All those free radicals come in many varieties and affect different parts of the body. So you need many different antioxidants to protect yourself at different levels."

For example, he says, vitamin E, which is fat soluble, is incorporated into the LDL or triglyceride particle, forming a last line of defense against corruption by free radicals. Water-soluble flavonoids, by contrast, can be absorbed by most cells in the body, where they can presumably take free radicals out of circulation. But so far, these are only theories. All scientists know for sure is that people who eat foods rich in these two kinds of chemicals, flavonoids and carotenoids, seem to have less heart disease--and it's not even certain that there is a cause-and-effect relationship.

As for figuring out which of the thousands of phytochemicals is most important, that is decades away. Just as with vitamin E--and with studies that debunked beta-carotene supplements as cancer fighters a few years ago--it may turn out that phytochemicals work only in tandem with one another or with other chemicals found in foods. Trying to find the "active ingredient" might be a fool's errand. Says Dr. Ronald Krauss, a nutrition and cholesterol researcher at the Lawrence Berkeley Lab in California: "It's premature to interpret that research in any way other than you should eat more fruits and vegetables."

INFECTION AND INFLAMMATION

Just a couple of years ago, one of the few things scientists were pretty sure did not trigger cardiac problems was infection. They're not quite so sure anymore. Evidence now suggests that the immune system plays a big role in heart disease. The initial damage is done by things like high blood pressure, smoking, oxidized LDL and triglycerides, which weaken and damage the inner walls of veins and arteries. Then the immune system responds, just as it's designed to do. Instead of fixing these problems, though, the immune response makes them worse. For one thing, the body tries to repair physical tears in blood vessels as it would any other wound: blood platelets rush to the site, clump together and form a clot, a biological bandage that binds up the injury. A clot on the outside of the body--a scab, in other words--eventually falls off with no problem. But inside a vein or artery, especially one that has been narrowed with plaque deposits, a clot can get snagged, causing a heart attack.

Plaque buildup too may be an unintended by-product of immune-system action. When oxidized fatty molecules damage vessel walls, the tissues become inflamed--engorged with immune cells whose job it is to fight the invaders. Instead of vacuuming up the oxidized molecules, however, the immune cells become entangled with them; the whole mess welds itself onto the tough, sticky plaques that narrow veins and arteries. That, researchers believe, is one reason aspirin is so good at preventing second heart attacks: not only does it thin the blood, it also damps down inflammation.

This same sort of blood-vessel inflammation may be triggered by bacterial and viral infections. Chlamydia (which generally starts as a venereal disease) and gingivitis (a gum infection) have 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 lots of saturated fat (in the form of butter, cheese and other milk products), yet they have one of the lowest rates of cardiovascular disease. One 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 suggests a cause-and-effect relationship, but after decades of study, the link between homocysteine and heart disease is elusive. Says Dr. Andrew Bostom, co-director of the Cardiac Rehabilitative program at Memorial Hospital in Pawtucket, Rhode Island: "We might be dealing with a real risk factor, but we don't have smoking-gun evidence."

They do, however, have an explanation for how homocysteine possibly works. If too much circulates in the blood, 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 is a significant cause of heart disease, the treatment is in hand: studies have shown that homocysteine can be controlled with B vitamins and folic acid, either in the diet or in supplements. The most recent study appeared four months ago in the New England Journal of Medicine: a U.S. 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 reduced homocysteine levels across the board.

New risk factors identified, old risks reassessed, 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.

When you step back, though, and take a look at the overall picture--a long view from the upper slopes of the mountain--it turns out that the path was clear. So it is with medical science. From the perspective of 1999, the past 40 years' worth of research points to a consistent theme: eat a balanced diet that includes lots of fruits and vegetables and fewer animal-based foods; don't smoke; and get as much exercise as you can comfortably maintain.

If it sounds as though nothing much has changed in the past three decades, that's because the fundamentals of cardiac health--the base of the mountain--have been there all along. What has changed is doctors' understanding of why it's all true. And they're continuing to refine their knowledge so that the confusing new research emerging from the labs will one day stand on an equally firm footing. Until that happens, the best bet is to focus on those basics. Your heart will thank you for it.

Reported by Christine Gorman and Alice Park/New York




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