'N ondersoek na die invloed van dieet op die hoë-digtheidslipoproteïene

Abstract

The concentration of cholesterol in high density lipopro- tein (HDL-C) is inversely related to the incidence of coron11ry heart disea e. It has been suggested that the 11ati-atherogenicity of HDL-C is associated with a sub- fraction thereof. Little information is however 11vail11ble on the effect of dietary manipulation on HDL subtraction distribution. The purpose of this investigation was therefore to study the effects of three different dietary manipulations on total HDL-C, HDL subfractions and other lipoproteins in subjects under free living conditions. The quantitative determination of the HDL subfractions was based on discontinuous poly.qcryl11mide gel electro- phoresis. In the first study soy protein was substituted for beef protein in the diets of 18 healthy subjects. Each of the experimeat11l periods lasted 3 weeks. For period l the protein consisted mainly of beef; for period 2 of a mixture of beef and soy and for period 3 of a soy con- centr11te. Men showed 11n increase in the HDL-C and HDL 3 -c levels on the soy diet. Diets containing soyprotein re- sulted in a decrease in the total cholesterol (TC) levels in the women. The second study was done on 11 obese subjects. Levels of HDL-C and other lipoproteins were measured before and after a 16-week weight reduction program. Again, there were significant differences between men and women. In men, a 7,0 kg weight loss was associated with a 15 % i ncrease in HDL-C level and a 197. increase in HDL 3 -c. Total cholesterol (TC ) and low-density lipoprotein cholesterol (LDL-C ) levels decreased 15 % and 22% respec- tively. No significant changes in the lipoprotein choles- terol distribution were observed in the women. [⁨NoIcon⁩ Annotation] [⁨NoIcon⁩ Annotation] In the final study fibre supplements were given to 13 hypercholesterolemic subjects. The subjects took Fibre T r i mR , Ma n n a n L i f e' s DF R ( k o n j a c - g 1 u c o ma IJl1:i n li n ) , "i mi x - ture of different dietary fibres pectin and bran) lind a placebo (cornstarch) in addition to their habitulil diets in a crossover design for 4 week periods with Wlish-out periods inbetween. During the experimental periods the mean daily intake of fibre ranged from 12,9g (placebo period) to 32,9g (mixed fibre). HDL 2 increased after 2 weeks of Fibre TrimR supplementa- tion. With fibre mixture supplementR-tion, HDL 2 increased Sind TC decreased. With konjac-glucomannan intake, HDL increased lind TC decreased. The HDL LDL ratio increased after trelitment with all types of dietary fibre. These beneficial effects were probably due to decreased choles- terol and lipid 4bsorption and decreased bile acid reab- sorption.