HEART disease is usually the consequence of years of poor health. The endothelial cells that line a healthy person's blood vessels secrete substances that not only assist blood flow but also prevent the build-up of plaques—dangerous clumps of protein that, if dislodged, can cause a heart attack by blocking the coronary arteries that feed blood to heart muscle. If the endothelial cells become damaged, however, plaque can build up. In fact, some doctors reckon the true illness is the narrowing and hardening of the arteries that accompanies this plaque build-up, and that heart attacks are merely the most obvious result.

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