Dose-dependent Effects of Hydro-methanolic Extract of Macadamia Nuts on Lipid Profile and Glucose Metabolism in Male Wistar Rats

Abstract

Aim: To investigate the role of hydro-methanolic extract of Macadamia integrifolia nuts extract on lipid and glucose metabolism in adult male Wistar rats. Study Design: Experimental, controlled, dose–response animal study was employed. Place and Duration of Study: The study was conducted in an animal house of the Department of Human Physiology, Rivers State University, Nigeria over a period of 28 days. Methodology: Twenty-four male Wistar rats were randomly assigned into four groups (n=6 per group): control, low dose (250 mg/kg), medium dose (500 mg/kg), and high dose (1000 mg/kg) of hydro-methanolic Macadamia integrifolia nuts extract. The extract was administered daily for 28 days. At the end of the treatment period, blood samples were collected for biochemical analysis of total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), high-density lipoprotein (HDL), very low-density lipoprotein (VLDL), and fasting blood glucose (FBG). Atherogenic indices, including Castelli’s Risk Index I (CRI-I), Castelli’s Risk Index II (CRI-II), and atherogenic coefficient (AC), were calculated. Data were expressed as mean ± SEM, and statistical significance was set at p<0.05. Results: The extract produced a biphasic, dose-dependent effect. The extract produced a biphasic, dose-dependent effect. Low-dose administration induced dyslipidaemia and elevated atherogenic indices, whereas medium dose partially attenuated these effects. High-dose administration restored lipid profile, fasting glucose, and atherogenic indices to near-control levels, indicating a protective metabolic effect. Conclusion: Hydro-methanolic Macadamia integrifolia extract exerts dose-dependent, biphasic effects on lipid and glucose metabolism, with low doses adversely affecting and high doses improving cardiovascular risk markers. The modulation of atherogenic indices underscores its translational relevance for nutraceutical development and cardiometabolic disease prevention.