The effect of milk proteins and curd on serum Angiotensin Converting Enzyme activity and lipid profile in Wistar rats

Abstract

Fermented milk and milk proteins have shown beneficiary health effects in humans. Angiotensin-II, which is formed from angiotensin-I by Angiotensin Converting Enzyme (ACE), plays a major role in regulating the blood pressure in humans and animals. Two experiments were carried out to determine the effects of prolonged consumption of milk proteins (casein & whey) in comparison with fermented milk (curd) on serum ACE activity and lipid profiles in Wistar rats. In experiment I, test groups were given 2 mL of hydrolysed casein or curd, whilst in experiment II, test groups received 2 mL whey and controls received 2 mL of water. The percentage differences obtained for individual animals were analysed after eight weeks. Casein hydrolysate fed group had a 4.3% reduction in serum ACE activity when compared with 3.5% reduction in curd hydrolysate fed group. The mean percentage difference of ACE showed significantly lower values (p < 0.05) in both casein and curd fed group when compared with the control. A greater reduction in serum total cholesterol was noted in the curd fed group (7.3%) when compared with the whey fed group (5.4%) and the casein treated group (0.8%). The mean percentage difference was significant (p < 0.05) only in the curd and whey treated groups. There was no significant difference in feed intake, body weight, serum high density lipoprotein cholesterol and triglycerides, between the treated groups and the control groups. This indicates that both casein and curd have the effect of lowering serum ACE activity.

Keywords: Angiotensin Converting Enzyme activity, casein, fermented milk, lipid profile, whey.

doi :10.4038/jnsfsr.v37i3.1215

J.Natn.Sci.Foundation Sri Lanka 2009 37 (3):209-214