Serum cholesterol response to changes in the diet: II. The effect of cholesterol in the diet.

The series of metabolic ward experiments, with 22 physically healthy men in each, covered dietary cholesterol intakes from 50 to 1450 mg. daily, with all other variables controlled. The serum-cholesterol data, plus the data from comparable experiments reported from 4 other institutions, were analyzed in regard to average serum cholesterol response (Δ Chol., mg./100 ml.) to changed cholesterol intake. Least-squares solution, using serum cholesterol responses in 19 sets of dietary cholesterol comparisons, gives Δ Chol. = 1.5(Z2 − Z1), where the subscripts refer to the diets compared and Z is the square-root of the dietary cholesterol, measured as mg./1000 Cal. The correlation between the average Δ Chol. predicted and that observed is r = 0.95. The serum response was the same over a wide range of dietary fat composition. Ordinary American diets range from about about 150 to 350 mg. cholesterol/1000 Cal. These extremes correspond to an average difference of about 9 mg. of cholesterol/100 ml. of serum if all other variables are constant. Change from 250 mg./l000 Cal. to a cholesterol-free diet will cause an average fall of about 24 mg./100 ml. of serum. But a 50 per cent decrease in dietary cholesterol will produce an average decrease in the serum of only about 7 mg./100 ml. For the purpose of controlling the serum level, dietary cholesterol should not be completely ignored but attention to this factor alone accomplishes little.