Dietary cholesterol effect on total serum cholesterol level
Keys Equation versus Hegsted!
For many years the Keys and the Hegsted equations, derived from their independent metabolic ward studies of diet effects on total serum cholesterol level, were remarkable for their comparability and robustness for fatty acids effects. But the Hegsted equation showed a linear relation of dietary cholesterol to serum cholesterol while the Keys equation found a curvilinear (parabolic) relation, thus Hegsted tended to overestimate the effect. The Keys finding was the basis for Keys’s argument that diet cholesterol was relatively unimportant, in comparison with saturated fatty acids raising effect. It also explained the faulty diet experiments that found no significant effect of adding eggs to the “usual American diet” (already containing an egg or two a day!)
This correspondence brought them closer on the estimated effect of dietary cholesterol, but Keys’ indirect letter of response, submitted for publication, might have done better to resolve the “attitudinal” difference. (HB)