The Harvard Medical School Guide to Men's Health: Lessons from the Harvard Men's Health Studies (Well-Being Centre = Centre Du Mieux-Etre (Collection)) - Softcover

Über die Autorin bzw. den Autor

Harvey B. Simon, M.D., is a physician at Massachusetts General Hospital and a founding member of the Harvard Cardiovascular Health Center. An associate professor of medicine at Harvard Medical School and a member of the Health, Sciences, and Technology faculty at the Massachusetts Institute of Technology, Dr. Simon is the founding editor of the Harvard Men's Health Watch and author or co-author of four trade books and more than 100 scholarly articles and medical textbook chapters.

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Chapter Six: The Answers: Aspirin and Other Supplements

"If only there were a pill."

Every man would like an easy way to stay healthy. Good nutrition and regular exercise are the keys for preventing illness, but diets take discipline and exercise takes time. Is there a shortcut? Can a few pills do the trick? Can "all-natural" supplements replace the physical activity and healthful eating that should be part of human nature?

If you look for the answer on the Internet or listen for it on TV or radio, you are likely to come away with a resounding "yes." That's mostly because vitamins, herbs, and other supplements are not subject to the jurisdiction of the Food and Drug Administration. Congress took care of that in 1994, when it passed the Dietary Supplement Health and Education Act. As a result, the supplement industry can tout its products without having to substantiate their claims for efficacy and safety. With billions of dollars at stake, the hype is relentless. In all, more than 50 percent of all Americans take supplements, spending upwards of $4 billion a year to buy health in a bottle.

Most doctors have been skeptical of supplements, pointing out correctly that anecdotes and testimonials can never be relied on in place of sound scientific studies. In the past few years, though, good studies have started to appear. While few herbs have been scrutinized, research by the Physicians' Health Study, the Health Professionals Study, and other investigations suggests that some supplements may be helpful while others are wasteful or even harmful. Surprisingly, perhaps, one of the most promising of all is not a vitamin or an herb, but an inexpensive, old-fashioned, medicine chest standby: aspirin.

Aspirin

Its name is more than a century old, but its parent compound has been in use for thousands of years. The ancient Assyrians, Egyptians, and Greeks all used willow leaves to treat inflammation, fever, and pain. The practice was popularized in England by Reverend Edward Stone in 1763. The active ingredient was purified from willow bark in Germany sixty-five years later. At the tail end of the nineteenth century, scientists at the Bayer Company succeeded in producing the modern derivative, acetylsalicylic acid, or aspirin. The very same drug has been used for fever and pain ever since. In the past thirty years, it has gained new importance in the management of heart disease and stroke, and current studies suggest it may someday assume a role in preventing colon cancer and possibly even Alzheimer's disease. And just as aspirin is finding new uses, scientists are finding out exactly how it works. It is important research that is likely to result in a new generation of even better drugs. But even in the dawning era of "super-aspirins," the original drug is certain to retain much of its value.

How It Works

Aspirin does its job by inhibiting the body's production of prostaglandins. Although you may never have heard of them, prostaglandins have a wide-ranging impact on human health. For example, they keep the stomach lining healthy, they regulate blood flow to the kidneys, and they enable platelets to trigger blood clotting. But prostaglandins also contribute to disease; in the brain they cause fever, and in joints and other tissues they can produce inflammation and pain.

Aspirin is not the only drug that inhibits prostaglandins. In fact all the nonsteroidal antiinflammatory drugs (NSAIDs) act in similar fashion (see Table 6.1, page 168). But although acetaminophen (Tylenol and other brands) fights fever and pain as well as aspirin, it does not inhibit prostaglandins. As a result, it does not share either the antiinflammatory benefits or the major side effects of aspirin and other NSAIDs.

Aspirin and Atherosclerosis

Aspirin does not prevent or even minimize atherosclerosis, but it can help prevent heart attacks and some strokes. It sounds like a paradox, but it is not. Aspirin cannot prevent cholesterol-laden plaques from building up in the wall of an artery, though it may be able to reduce the inflammation that perpetuates the damage (see Chapter Three and Figure 3.1). But while plaques narrow arteries, rarely do they produce the complete blockages that cause heart attacks. Instead, the culprit is a blood clot or thrombus that forms on the surface of a ruptured plaque. The clot completes the blockage, and aspirin exerts its protective effect by inhibiting clot formation.

Clots are triggered by platelets, fragmentary blood cells that are produced in the bone marrow, and then pour into the bloodstream. A man's blood contains a total of 100 million platelets, but because each platelet only lasts about ten days, the marrow must produce them continuously at a prodigious rate. Aspirin does not reduce the number of platelets in the blood, but it does inhibit their ability to trigger clots.

Platelets are extremely sensitive to aspirin. In some studies, doses as low as 10-30 milligrams can inhibit all the platelets in a man's body. Once platelets are inhibited by aspirin, they stay inhibited, but since new platelets are entering the blood continuously, the aspirin dose must be repeated every twenty-four to forty-eight hours to keep the majority of platelets under control.

Primary Prevention of Heart Attacks

You would probably call it staying healthy, but doctors call it primary prevention. By either name, it means heading off a problem before it makes its first appearance. Can aspirin prevent a first heart attack in men without diagnosed heart disease?

This is the question that the Physicians' Health Study set out to answer in 1982. A total of 22,071 male physicians volunteered to be subjects in a randomized clinical trial of low-dose aspirin. Half the men were assigned to take 325 milligrams of aspirin every other day, while the others each were given an identical-appearing placebo tablet every other day. To eliminate bias, the assignments were made randomly and neither the subjects nor the researchers knew which men were taking aspirin and which the placebo.

The researchers had planned to continue the trial until 1990, but it was terminated three years ahead of schedule. That was because an independent Data Monitoring Board that was tracking the results declared it would be unethical to continue the study since a clear winner was already evident. The winner was aspirin.

In the Physicians' Health Study, the men who took aspirin had a 44 percent reduction in the risk of suffering a heart attack. Benefit did not depend on a man's family history of heart disease or on his cholesterol, blood pressure, blood sugar, body fat, amount of exercise, or his drinking or smoking habits. But one risk factor did predict benefit: age. Aspirin was highly effective in men older than fifty, but not in younger individuals.

The results of the Physicians' Health Study were published in the same year as the report of the British Doctors Trial, which found no benefit from aspirin. Does that mean men should take aspirin in America but not in Europe? Not at all. The British trial was much smaller than the U.S. study, involving just 5,139 men. It was also less carefully controlled. But the biggest difference was in the dose of aspirin; the British doctors took 500 milligrams every day, the Americans just 325 milligrams every other day.

When you have a headache or a fever, you are likely to take two 325 milligram aspirin tablets every four to six hours. Even the British doctors' dose is tiny in comparison, but it may still be too high to produce maximum protection against heart attacks. That is because tiny doses of aspirin will inhibit only thromboxane A2, the enzyme in platelets that triggers the clotting process, but higher doses can also inhibit prostacyclin, an enzyme in blood vessels that reduces clotting....