Protective effects upon experimental inflammation models of a polyphenol-supplemented virgin olive oil diet.

OBJECTIVE AND DESIGN

The aim of the present study was to examine the effect of a virgin olive oil enriched diet in acute and chronic inflammation models in rats and to determine the effect of supplementing this oil with a higher content of its polyphenolic fraction. The response was compared to oils rich in monounsaturated fatty acids (high oleic sunflower oil and palm olein) and rich in polyunsaturated fatty acids (fish oil). DIETS: Groups of 6-8 male Wistar rats were fed from weaning on six purified diets differing in type of oil: 2% corn oil (basal diet, BD), 15% high oleic sunflower oil (HOSO), 15% virgin olive oil (VOO), 15% virgin olive oil supplemented with 600 p.p.m. polyphenols from this oil (PSVOO), 15% palm olein (POL), and 15% fish oil (FO).

MATERIALS AND METHODS

Rats were fed for 8 weeks with BD, HOSO, VOO, PSVOO, POL and FO diets before injecting carrageenan. Rats were fed for 3 weeks with BD, PSVOO and FO diets before induction of adjuvant arthritis. Dietary treatment with or without indomethacin continued during 3 weeks. The data were evaluated using an analysis of variance (ANOVA) followed by the least-significant differences.

RESULTS

In carrageenan oedema test, the inflammation indices of animals fed on a diet rich in olive oil (VOO) were lower compared to animals fed with oils high in oleic acid (HOSO, POL) and polyunsaturated fatty acids (FO), and markedly diminished in the group fed on PSVOO. In established adjuvant arthritis, the PSVOO diet was even more effective than FO diet in the prevention of inflammation. Both groups of animals showed an increase in weight during the latter days of the experiment compared to the BD. Indomethacin administered to every diet group, exerted a strong inhibitory effect on the inflammatory process throughout which was augmented by the PSVOO and FO diets.

CONCLUSIONS

This study demonstrates that virgin olive oil with a higher content of polyphenolic compounds, similar to that of extra virgin olive oil, shows protective effects in both models of inflammation and improves the disease associated loss of weight. This supplementation also augmented the effects of drug therapy.