Hyper-response to dietary cholesterol in man.

SIR,-In animals the response of serum cholesterol to dietary cholesterol is genetically determined, and non-responders, with only small changes in serum cholesterol after dietary cholesterol, and hyper-responders have been defined. In man response to cholesterol in the diet is very varied2 but since dietary challenge is usually done only once the reproducibility of the response is not known and the existence of human hyper-responders remains uncertain. Hyper-response to dietary cholesterol in man would be important because genetic disorders, such as familial hypercholesterolaemia and combined hyperlipidaemia, account for only a small percentage of the hypercholesterolaemia found in affluent populations. We reinvestigated 17 men and 17 women (aged 23-78) who habitually consumed at least one egg a day and had participated in a trial in 1976.3 Blood sampling and serum cholesterol analysis were standardised.4 Serum cholesterol was measured twice on the eggrich diet and again after 3 weeks during which the subjects ate no eggs or egg-containing products. Daily cholesterol intake on the two diets averaged 840 mg and 303 mg in 1976 and 811 mg and 245 mg in 1982. Mean serum cholesterol values fell by 0 16&plusmn;0’ 42 mmol/1 in 1976 (range -1-27 to +0-51)andby0-31&plusmn;0-35mmol/iinl982 (range -0-94 to +0 . 48). Individual responses in 1976 and 1982 were correlated (r=0-32, p<0-05), suggesting that part of the serum cholesterol response to dietary cholesterol is indeed individually determined. This finding ’was confirmed in further studies. In the first experiment, ninety-four healthy men and women aged 18-72 consumed 10 mg cholesterol per MJ (on average 110 mg/day) for 14 days and 55 mg/MJ (610 mg/day) for another 14 days; blood was sampled twice on each diet. Almost all food was supplied by us and intakes were rigidly controlled. 5 Cholesterol (egg yolk) was the only dietary variable. The increased intake caused an increment in serum cholesterol concentrations of 0 50&plusmn;0’ 39 mmol/1 (mean &plusmn;SD), with individual responses ranging from -0-62 to +1-63 mmol/1. Fifteen non-responders and seventeen hyper-responders, with increases of -0-01-tO-21 and 0-96--tO-27 mmol/1, respectively,