Risk factors for coronary heart disease: Synthesis of a new hypothesis through adaptation

Abstract

A risk factor is a characteristic which is associated with a greater than average probability of developing coronary disease. Raised serum cholesterol and hypertension are two such factors. Intervention studies conducted to confirm the risk factor hypothesis have shown that reduction of serum cholesterol and essential hypertension may be associated with a small decreased CHD incidence, however there were almost as many deaths due to coronary disease in the intervention groups as in the control groups. These findings suggest that our approach to risk factor intervention may be a misguided attempt which needs modification. It is possible that the major risk factors develop in an attempt of our body to adapt to environmental factors such as increaed intake of salt, saturated fat and cholesterol, physical inactivity, increased intake of calories and obesity and stress. Smoking may be the result of social changes. Since the body has to modify its metabolic mechanism depending upon the factor to which it adapts, development of hyperlipidemia and hypertension may be protective mechanisms of the body which it has developed while fighting against environmental factors. Reduction of major risk factors by drug therapy may mean that we are trying to prevent the body, fighting environmental factors. Thus our approach to control of the major risk factors should be to treat the causative environmental factors or alter the lifestyle. There is evidence that diet, physical inactivity and obesity are most important in the pathogenesis of major risk factors and dietary changes, weight loss and increased physical activity may be independently associated with substantial reduction in hypertension and hyperlipidemia leading to decreased CHD and total mortality and retardation in atherosclerosis. More evidence is necessary to confirm the role of these methods in the management of risk factors and prevention of CHD and to confirm the present hypothesis.