Eat Your Heart Out

Few decades ago, taking care of your heart didn't seem complicated. You ate a balanced diet, didn't drink too much and got some exercise--a round of golf, maybe. That was about it. Not that everyone, or even most people, actually lived up to these standards. But if you fell short, at least you knew what to feel guilty about.
Then we started hearing from the scientists. People who thought they were doing everything right, it turned out, were actually abusing their bodies--and their hearts. The cholesterol in steaks, cream, butter and eggs was clogging arteries like sludge in a stopped-up drainpipe. Salt was poison: it drove up blood pressure and put an unhealthy strain on the ticker. Overeating and becoming overweight were a ticket to a coronary.

So, the thinking was, better cut out the steak, treat yourself to one egg a week (if you must), switch from butter to margarine and hide the saltshaker. Oh, and don't waste time with golf. Vigorous, pulse-pounding exercise was the only way to keep your weight within limits--and just as important, your heart properly toned. It was a spartan regimen and made folks who didn't follow it feel guiltier than ever, but it retained the virtue of being comprehensible.

Recently, though, scientists seem to have gone mad. Hardly a week goes by without an expert issuing a report declaring that a particular food or vitamin or activity or condition will either restore cardiovascular health or ruin it--and often the new advice seems to contradict the old. Among the new findings:

Eggs aren't nearly as bad for the heart as doctors used to think. Sure, they're packed with cholesterol. But scientists now know that eating cholesterol doesn't necessarily result in high levels of harmful cholesterol in the blood, where the damage is done.

Homocysteine, a substance in blood, may be as big a risk for heart disease as dietary cholesterol.

Saturated fat, found in red meat, butter and other animal products, may be a bigger threat to the heart and blood vessels than cholesterol.

Other fats--olive oil, other vegetable oils and the oil found in salmon and tuna--can drive down bad cholesterol and keep blood flowing freely.

Margarine can be just as harmful as butter, if not worse; a process that stiffens vegetable oil into a butter-like stick also transforms it into an artery blocker. In general, the softer the margarine, the better. New butter substitutes, such as Benecol, can lower blood cholesterol.

Salt has been considered taboo because it raises blood pressure. But it's not clear whether it's a problem for those whose pressure is normal.

Exercise need not be pulse pounding to be beneficial, say experts. A little gardening or strenuous housework isn't a bad prescription for cardiovascular health.

The impression being given, admits Dr. Irwin Rosenberg, dean of nutrition sciences at Tufts University School of Nutrition, Science and Policy near Boston, is that nutrition science doesn't know what it's doing. But despite appearances, the medical profession has not lost its collective mind. The bewildering flood of advice that assaults us week after week simply reflects the slow, laborious gathering of knowledge that defines science in action. Like most works in progress, it moves ahead in fits and starts--and occasionally goes down a blind alley.

Yet despite the apparent confusion, scientists know more today about what keeps the heart humming than they did a generation ago. The first glimmerings of understanding gathered 30 years ago were accurate as far as they went--but rudimentary. Today scientists have a much deeper understanding of what foods and activities are healthful or harmful--and why. The good news is that the path to a healthier heart is now pretty clear, once you master a few key concepts.

FAT AND CHOLESTEROL

Fat has been a staple of the human diet since our remote ancestors started eating meat more than 2 million years ago. In the 1960s, however, researchers began to notice that patients who had elevated blood levels of cholesterol--a fatty substance found in meat, poultry, eggs and dairy products--also tended to suffer from heart disease. Cholesterol by-products would form thick, tough deposits, called plaques, on the inner walls of arteries, stiffening them and then starving the heart of blood and creating choke points where a clot could stop the flow entirely.

At first blush, the solution seemed obvious: consume low-cholesterol foods; switch from butter to vegetable-oil-based margarine; eat fewer eggs; eat less meat. Indeed, it was the best advice at the time, based on the limited knowledge available.

As scientists learned more about how the body works, however, that prescription proved too simplistic. Some people's cholesterol levels stayed high, no matter what they ate. And a lot of heart-disease patients had normal cholesterol levels. Only recently have reasons emerged. For one thing, how much cholesterol you eat doesn't necessarily determine how much ends up in your blood. The body, it turns out, also manufactures its own cholesterol. And some people's bodies are just less efficient at vacuuming up excess cholesterol than others, for reasons that are largely genetic.

So, in the next phase of research, the object became keeping cholesterol levels in the blood under control and not necessarily keeping the cholesterol out of the diet. But how to do it? Again the key seemed to be eating less red meat, cream and butter, but it was based not so much on cholesterol as on saturated fat. Reason: saturated fat increases blood cholesterol. So eggs, high in cholesterol but not in saturated fat, were taken off the forbidden list, except for those people with the most serious cholesterol problems.

To make things more complicated, researchers discovered that cholesterol travels around the body in two major forms: low-density lipoprotein (LDL), the kind that does most of the damage, and high-density lipoprotein (HDL), which actually seems to keep arteries clean. Beyond that, another class of fats, known as triglycerides, also circulates in the blood, doing more or less the same kind of damage as LDL.

Doctors then began recommending foods and activities that drive down LDL and triglycerides (eat less meat, cream and butter--one recommendation that has never changed--add olive oil and fish to the diet) and at the same time push up HDL (get more exercise and lose weight).

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