Lipoproteins and cholesterol esterification rate in plasma during a 10-day modified fast in man

The influence of a 10-day modified fast on the concentrations of lipids and lipoproteins and the rate of cholesterol esterification in plasma was studied in 12 subjects with rheumatoid arthritis. The subjects were randomized and seven patients completed the period of fasting while the others served as controls. During the withdrawal of nutrients a rich supply of fluids, at least 2.7 to 3 liter/day containing around 200 kcal was given as fruit or vegetable juices and teas. After 10 days of fasting the concentrations of cholesterol and phospholipids in plasma were reduced by a mean of 21 and 11%, respectively, based on a 27% mean reduction of these lipids in the low density lipoprotein fraction. In all fasting subjects but one there was a reduction of the triglyceride concentration in the very low density lipoprotein fraction. The high density lipoprotein fraction was unchanged. The molar and fractional cholesterol esterification rates in plasma were reduced by a mean of 27 and 8.5%, respectively, after 10 days of fasting compared to the prefasting levels. The rate of cholesterol esterification in plasma is believed to reflect the turnover of cholesteryl esters in plasma, which therefore seemed to be reduced during fasting. The present findings might be explained by deprivation of specific nutrients or by a generally reduced metabolic rate during energy deprivation.