Effect of Fresh and Stored Palm Oil on Oxidative Stress and Inflammatory Markers in Wistar Rats
Ojeaburu S.I.
Asiriuwa N.U.
Abstract
Palm oil is the most widely consumed vegetable oil globally, valued for its balanced composition of saturated and unsaturated fatty acids and its richness in phytonutrients such as carotenoids, tocotrienols, and phytosterols. This study examined the effects of varying free fatty acid (FFA) levels in palm oil on oxidative stress and inflammatory responses in Wistar rats. Thirty-six rats were divided into six groups of six rats each: Group I received a normal diet, while Group II served as the experimental control and was given fresh palm oil (0.4% FFA). Groups III–VI were administered palm oil with increasing FFA levels (4.8%, 8.4%, 21.9%, and 42.7%) obtained from oil stored for sixteen months. After four weeks of oral administration (480 mg/kg body weight), oxidative stress markers—superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), malondialdehyde (MDA)—and inflammatory cytokines (IL-6 and IL-10) were analyzed using standard methods. Fresh palm oil did not significantly alter antioxidant enzyme activities or MDA levels, while oils with elevated FFA content markedly reduced SOD, CAT, and GPx activities. IL-6 levels were significantly lower (p < 0.05) in rats fed both fresh and stored oils compared with controls, but IL-10 and IL-6/IL-10 ratios showed no significant changes (p > 0.05). Rats receiving highly oxidized oils (21.9% and 42.7% FFA) exhibited the greatest cytokine reduction. These findings suggest that its FFA content influences the nutritional and health effects of palm oil; thus, proper processing and storage are essential to preserve its quality.
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