Adaptive changes in aging and arteriosclerosis--role of cholesterol

The "lipid theory" assumes that cholesterol has a causal part in the development of arteriosclerosis; however, in view of the fact that cholesterol has always accompanied life processes, the "lipid theory" contradicts the evolutionary principle of "teleonomy" which predicts that long lasting metabolic effects must have beneficial consequences. Support for the theory was claimed from the correlation between high serum cholesterol and arteriosclerotic complications, from observations in cholesterol fed animals and from cardiac lesions in familial hypercholesterolemia. However, correlations do not prove causality; whether the animal experiments and the observations in familial hypercholesterolemia are pertinent is questionable. Therefore, the possibility was considered that the cholesterol changes are an adaptive mechanism. This is supported by the "normal" cholesterol content of the early lesion, by the stabilization of the DNA helix by cholesterol in appropriate concentration, by the beneficial effects of cholesterol-rich granulomata; by recent reliable "intervention" trials with low cholesterol diets and by the observation that persons dying from ischemic heart disease (having high serum cholesterol) live at least as long as those dying from other causes. Furthermore, studies with serum cholesterol lowering drugs are difficult to interpret and often misleading. The symptomatology of the serum cholesterol changes in arteriosclerosis suggests that they belong to the adaptive aging phenomenon. This would be in line with evolutionary thinking.