Prevention Of Heart Disease - Part 2

Two fairly important factors about which one can little are which sex you are and heredity. Women are less prone to the disease than men, and people whose parents and grandparents had the disease do inherit some risk of it. These people therefore need to pay greater attention to other risk factors.

Number one on the list is smoking. The evidence that it profoundly accelerates coronary heart disease, lung cancer and other diseases of the chest is overwhelming. Although heavy cigarette consumptions causes greatly increased risk, all cigarettes create some risk. In a society where coronary disease is a major killer, smoking can only be considered a form of mass suicide.

Perhaps the next most important factor is physical inactivity. Studies of large populations over long periods suggest that active people have a lower Incidence of coronary disease than the inactive. As many people have very sedentary jobs with little physical activity and they also do not take part in any active , leisure pursuits, they must obviously be running an increased risk of coronary heart disease.

Two diseases which have been shown quite clearly to accelerate coronary problems are diabetes and
hypertension (high blood pressure), but both may be undiagnosed for long periods. Hypertension may remain undiagnosed until it causes a major complication, having been present, though not causing symptoms, for years or even decades. In the absence of symptoms, many hypertensive people are reluctant to take drugs to control blood pressure for years, especially as these drugs may themselves have minor side-effects. Nevertheless, if left untreated, both hypertension and diabetes cause a relentless progression of coronary disease, and probably also damage the heart muscle directly, in addition to their effects on the kidneys and the blood vessels of the brain. One important reason for a regular medical examination is to check for diabetes with a urine test and hypertension with a blood pressure measurement. These simple measures can play a major part in preventive medicine.

Reference has already been made to the possible effect of diet on the progression of coronary disease. Experimental data has suggested the link between disease of the arteries and high blood levels of cholesterol and related and related fatty substances, and additional link between high blood levels of these compounds and a high dietary intake of cholesterol and saturated fatty acids. The view that these links are important rests largely on data from experiments with animals which have shown that, in some species, narrowing of the arteries can be induced by feeding animals diets rich in cholesterol and saturated fatty acids. Other evidence has suggested that there is a statistical link in large populations between blood cholesterol levels and death from coronary disease, and that a change in diet may later cholesterol levels; and there has also been the suggestion that this change of diet may have some effect on the incidence of what are called 'coronary events' (these include the onset of angina, heart attacks, sudden death, etc.). For these reasons modification of diet has been proposed which would severely limit the intake of foods containing cholesterol (such as eggs) and animal fats.

There are, however, several flaws in these arguments which suggest that the wholesale introduction of diets of this type may not achieve the desired reduction in heart attacks and coronary deaths. Not all the animals that have undergone these experiments have developed arterial disease, many species appearing to be relatively immune, and it is uncertain to what extent the results can be applied to man, many of the animals' diets having been so grossly abnormal that they probably bear little relationship to human diets. Secondly, although it can be shown that a change in diet can statistically affect blood cholesterol levels in large populations, the effects of a change of diet in an individual cannot be predicted. Frequently an increase in the amount of cholesterol that is eaten is offset by decreased production within the body or increased excretion, so that there is often little overall effect on blood levels. Thirdly, a reduction in cholesterol levels has yet been shown to be effective in preventing the onset of arterial disease or to reduce the rate of heart attacks, nor has it been shown to reverse the progress of the disease once it has become established. Finally, large-scale studies, which have suggested that diets low in cholesterol and saturated fatty acids reduce the incidence of 'coronary events', largely based on statistics which are suspect.

A further word of caution must be mentioned. It has become fashionable in recent years for doctors  to prescribe cholesterol-lowering drugs—for example, clofibrate — although the value of reduced cholesterol levels is in doubt as mentioned above. In one study of 15,000 people who took this drug, the results showed that, although there was a decrease 'coronary events', there was no reduction in the total number of deaths and there was even an increase in deaths from disease of the gastrotestinal system. There is therefore a strong argument against the introduction of new drugs on such a large scale until carefully controlled studies e been carried out.