Abstract

The effects of soy protein on the activities of serum lactate dehydrogenase (LDH), alanine aminotransaminase (ALT), aspartate aminotransaminase (AST) and gamma-glutamyl transpeptidase (γ-GT) in rats fed cholesterol-diet were investigated. Rats were subjected to feeding over a period of six weeks on formulated diets containing: 20% soy protein with no cholesterol (group A); 20% soy protein with 5% cholesterol (group B); 20% soy protein with 10% cholesterol(group C): 0% soy protein with 20% cholesterol (group D); and  5% soy protein with 20% cholesterol (group E). The serum levels of these enzymes were determined weekly for the six weeks treatment period. LDH, ALT, AST and γ-GT activities were observed to be significantly elevated (p < 0.01) in groups D and E when compared with groups B and C although the enzymes activities in groups B and C were significantly higher (p < 0.05) when compared with the control. The activities of the enzymes were highest in group D. It is considered that consumption of soy protein-rich diets as opposed to those high in animal protein may help reduce oxidative damage to tissues (such as heart, liver, and kidney) and hence reduce cardiovascular disease risk due to the presence of soy isoflavones and its hypolipaemic attributes.

Key words: Soy protein, cholesterol, serum enzymes.