LONG TERM CONSUMPTION OF THERMOXIDISED OR PHOTOXIDISED PALM OIL DIETS IS ASSOCIATED WITH SYSTEMIC EXPRESSION OF OXIDATVE STRESS BIOMARKERS IN WISTAR RATS

Ekpe Okpata Aribo* and Nsikak Ephraim Udokang

ABSTRACT

Several researches have demonstrated that consumption of thermoxidised palm oil (TPO) or photoxidised palm oil (PPO) diets impairs tissue functions in many organ systems suggestive of a systemic toxicity. It is also known that lipid peroxidation of tissues results in tissue damage and consequent dysfunction from oxidative stress, a common pathway in many pathological conditions. But evidence on the general peroxidative status of the animals following long term ingestion of these forms of palm oil is lacking. Fifteen male wistar rats weighing 80 -122g and aged 20-23 weeks were divided into control, PPO-fed and TPO-fed groups of five rats each. Control group was fed on normal rat feed while the PPO-fed and TPO-fed groups were fed on PPO and TPO diets respectively for 13 weeks and their blood samples evaluated for serum catalase (CAT), glutathione peroxidase (GPx) and malondialdehyde (MDA) levels as biomarkers of oxidative stress. Serum MDA concentration in TPO-fed and PPO-fed groups was significantly increased (p<0.001) compared with control. It was also significantly increased in the PPO-fed group p<0.01) compared with the TPO-fed group. Serum concentration of CAT in the TPO-fed and PPO-fed groups was significantly decreased (P<0.01 and p<0.001 respectively) compared with control. Serum GPx concentration in TPO-fed and PPO-fed groups was also significantly decreased (P<0.05 and p<0.001 respectively) compared with control. In conclusion, long term ingestion of TPO or PPO diets is associated with systemic expression of oxidative stress biomarkers in wistar rats.

Keywords: Diet; Oxidative stress; Palm oil; Peroxidation; Photoxidation; Thermoxidation.