SOY LECITHIN REDUCES PLASMA-LIPOPROTEIN CHOLESTEROL AND EARLY ATHEROGENESIS IN HYPERCHOLESTEROLEMIC MONKEYS AND HAMSTERS - BEYOND LINOLEATE

The current study was designed to investigate the hypocholesterolemic and anti-atherogenic properties of soy lecithin beyond its fatty acid content. In experiment 1, 18 cynomolgus monkeys were divided into thre e groups of six and fed diets which approximated either the average Am erican diet (AAD), the American Heart Association (AHA) Step I diet, o r a modified AHA (mAHA) Step I diet containing 3.4% soy lecithin for 8 weeks. Plasma samples were collected from food-deprived monkeys and a nalyzed for total cholesterol (TC), high-density :lipoprotein choleste rol (HDL-C), very low- and low-density lipoprotein cholesterol (non-HD L-C), and triglyceride (TG) concentrations. Group comparisons revealed that monkeys fed the mAHA Step 1 diet had significantly lower plasma TC (- 46%) and non-HDL-C (- 55%) levels compared to the AAD diet, wher eas monkeys fed the AHA Step 1 diet had lesser reductions in plasma TC (- 21%) and non-HDL-C (- 18%) levels. The monkeys fed the mAHA Step I diet had significantly lower plasma TC (- 32%) and nn-HDL-C (- 45%) c ompared to the monkeys fed the AHA step diet. Also, only the mAHA Step I diet significantly reduced pre-treatment plasma TC and non-HDL-C le vels by - 39 and - 51%, respectively with no significant effect on pla sma HDL-C or TG levels. In experiment 2, 45 hamsters were divided into three groups of 15 and fed the following three modified non-purified diets for 8 weeks: a hypercholesterolemic diet (HCD) containing 10% co conut oil and 0.05% cholesterol, HCD plus 3.4% soy lecithin(+ SL), or the HCD with added levels of linoleate and choline equivalent to the SL diet but no lecithin (- SL). Plasma lipids were determined as in e xperiment 1 and aortas were perfusion-fixed and Oil Red O stained for morphometric analyses of fatty streak area. Relative to the HCD group, the + SL-treated hamsters had significantly lower plasma TC (- 58%), non-HDL-C (- 73%) and aortic fatty streak area (- 90%). Relative to th e - SL group, hamsters fed the + SL diet had significantly lower plasm a TC (- 33%), non-HDL-C (- 50%) and significantly reduced aortic fatty streak area (- 79%). In conclusion, the first experiment suggests tha t the cholesterol-lowering efficacy of the AHA Step I diet can be enha nced with the addition of soy lecithin without reducing plasma HDL-C l evels, whereas the second experiment suggest that the hypocholesterole mic, and in particular, the anti-atherogenic properties of soy lecithi n cannot be attributed solely to its linoleate content. (C) 1998 Elsev ier Science Ireland Ltd. All rights reserved.