1. Cholesterol esterification has been studied in the plasma of subjects on diets rich in saturated or polyunsaturated fat.
2. The diet rich in polyunsaturated fat was associated with lower rates of plasma cholesterol esterification in vitro. The data suggest that there was a reduction of plasma lecithin—cholesterol acyltransferase activity as well as decreased ability of the lipoprotein substrates of the enzyme to support esterification.
3. On this diet, there was no change in the proportion of the plasma cholesterol esterified but the plasma cholesterol and triglyceride concentrations were reduced.