Determination of the quality of coconut oil and the effects of selected coconut products on serum metabolic parameters of Wistar Rats.

Abstract

Although a large number of studies have. been conducted on the health effects of coconut, findings remain inconclusive. This study investigated the quality of commercially available coconut oil (CNO) and the effects of CNO and grated coconut on serum metabolic parameters in Wistar rats. The quality of 52 CNO samples obtained from retail and wholesale outlets in three districts were investigated. Most of the samples were adulterated with palm or coconut paring oil and were of inferior quality. White coconut oil (WCO) had a significantly higher total phenol content and antioxidant activity (p<0.05) as compared to virgin coconut oil (VCO). Effects of WCO and VCO on body weight, fasting blood glucose (FBG), serum lipids and hepatic antioxidant status were investigated using normocholesterolaemic (NC) and hypercholesterolaemic (HC) rats. Seven groups of rats (n=8) were maintained on diets containing WCO or VCO at a concentration of 2% or 4% for 36 weeks. No significant differences were observed in the body weights and FBG levels in any rat group after 36 weeks. In NC rats, no significant changes (p>0.05) were observed in serum lipid parameters including HDL. In HC rats, a significant increase in total cholesterol (TC) was observed in 2%WCO group (p<0.05) while no significant change was observed in 2%VCO comparing with baseline indicating a potential therapeutic effect of VCO in controlling serum TC in HC states. Similar findings were observed in the TC/HDL ratio. HC rats on 2% VCO diets had higher HDL and lower serum triglyceride levels than HC rats fed on 2% WCO, though the differences were not statistically significant (p>0.05). In NC rats, WCO diets resulted in higher hepatic lipid peroxidation (p<0.05) and hepatosteatosis (p<0.05) as compared to VCO diets. Incorporation of grated coconut into diets resulted in a significant hypoglycaemic effect (p<0.05) and lower serum triglyceride levels (p>0.05) as compared to diets ·containing oil only.

Key words: WCO, VCO, Quality, Serum lipids, Antioxidant activity