Addition of Guar Gum and Soy Protein Increases the Efficacy of the American Heart Association (AHA) Step I Cholesterol-Lowering Diet without Reducing High Density Lipoprotein Cholesterol Levels in Non-Human Primates

Manuscript received 8 December 1997. Initial reviews completed 4 February 1998. Revision accepted 22 May 1998.

Department of Health and Clinical Science, Center for Chronic Disease Control, University of Massachusetts Lowell, Lowell, MA 01854 and ^* Ross Products Division, Abbott Laboratories, Columbus, OH 43216

The aim of this study was to determine whether the addition of soy protein and guar gum to the American Heart Association (AHA) Step I diet would increase its efficacy compared with the typical "Average American Diet" (AAD) in a non-human primate model. Twenty adult female cynomolgus monkeys (Macaca fascicularis) were fed one of three diets for 6 wk. The AAD contained 36% energy from fat; the standard Step I diet contained 30% energy from fat; and the modified AHA Step I diet contained 30% energy from fat with the addition of soy protein isolate (10% of total energy) and guar gum (5.8 g/d). Plasma samples were collected from food-deprived monkeys at 4, 5 and 6 wk of dietary treatment for analyses of plasma total cholesterol (TC), lipoprotein cholesterol and triacylglycerol (TAG) concentrations. Plasma TC, LDL-C, HDL-C and TAG concentrations were not significantly different in wk 4, 5 and 6 within any of the diet periods; thus the three measurements were averaged. After 6 wk of dietary treatment, monkeys fed the standard Step I diet had lower plasma TC (19%) (P < 0.05) and LDL cholesterol (LDL-C) (24%) (P < 0.09) than when they were fed the AAD, with no effect on HDL cholesterol (HDL-C), the lipoprotein cholesterol profile or TAG. Beyond the effect of the standard Step I diet, the modified AHA Step I diet further reduced plasma TC and LDL-C (24% and 40%) (P < 0.05) and the TC/HDL-C and LDL-C/HDL-C ratios (37% and 52%) (P < 0.05) with no significant changes in plasma HDL-C or TAG. The primary conclusions of this study are that the efficacy of the AHA Step I cholesterol-lowering diet can be increased with the addition of soy protein and guar gum and provide a more favorable lipoprotein cholesterol profile. Whether the cholesterol-lowering effect is the result of soy protein or guar gum or a synergistic effect of both remains to be determined.

The Journal of Nutrition Vol. 128 No. 9 September 1998, pp. 1429-1433
Copyright ©1998 by the American Society for Nutritional Sciences