Heated palm oil causes rise in blood pressure and cardiac changes in heart muscle in experimental rats.

Background: Palm oil used worldwide contains considerable amounts of antioxidants, namely, vitamin E and carotenes. The purpose of the study was to observe the effect of heated palm oil on blood pressure and observe the cardiac histological changes in rats.

Methods: Forty male Sprague Dawley rats were divided equally into four groups and given treatment as follows: (i) basal diet (control group); (ii) basal diet fortified with 15% weight/weight (w/w) fresh palm oil (FPO); (iii) basal diet fortified with 15% w/w palm oil heated five times (5HPO); (iv) basal diet fortified with 15% w/w palm oil heated ten times (10HPO). Treatment duration was 16 weeks. Blood pressure was measured at baseline and at monthly intervals for 4 months using the tail-cuff method. After 16 weeks of study, the rats were killed and the hearts were taken out. The specimens were sectioned longitudinally and stained with hematoxylin and eosin for light microscopy.

Results: The FPO group did not show any significant changes in blood pressure and histological study. There was a significant increase (p <0.05) in blood pressure in the 5HPO and 10HPO groups. However, blood pressure in the 10HPO group was higher than in the 5HPO group. Histological sections of the heart showed necrosis in cardiac tissue in the 5HPO and 10HPO groups with the latter group showing more damage.

Conclusions: Fresh palm oil has no deleterious effects on blood pressure and cardiac tissue but prolonged consumption of repeatedly heated palm oil may result in an increase in blood pressure level with necrosis of cardiac tissue.