[Effect of olive oil on early and late events of colon carcinogenesis in rats: modulation of arachidonic acid metabolism and local prostaglandin E2 synthesis] 2000: 46 191-9
Olive oil may protect against bowel cancer, finds a study in Gut based on research conducted in rats. Previous research has shown that dietary fat helps to promote cancer, but that the development of malignancy is associated both with the amount and type of fat consumed.
Over 100 rats were divided into three equal groups to be fed diets rich in either safflower oil containing n6 fatty acids, fish oil containing n3 fatty acids, or olive oil containing n9 fatty acids. Each of the three groups was then further divided, and one half given a cancer inducing agent. Evidence of precursors to malignancy, numbers of tumours, and the fatty acid content of bowel tissue were all assessed up to 19 weeks after the start of the diets.
Rats fed the safflower oil diet had more precancerous tissue - aberrant crypt foci and polyps - and more tumours than rats fed either the fish or olive oil diets. These last two diets also reduced the amount of arachidonate, a chemical involved in the synthesis of an inflammatory substance called prostaglandin E, which, experimental evidence shows, promotes cancer formation. The amount of this substance was significantly increased in the rats given the cancer inducing agent and the safflower diet, but not in those fed either the fish or olive oil diets.
Olive oil contains 75 per cent oleic acid. Oleic acid is also found in beef and poultry and in other vegetable oils, such as corn, soybean, and sunflower seed oil, although in lesser amounts. Because the other fats and oils contained in these foods actually promote cancer, it is unlikely that oleic acid alone accounts for the beneficial effects of olive oil, say the authors. Rather, they suggest that the other constituents of olive oil, such as squalene, flavonoids, and polyphenols, are likely to protect against cancer.
Contact: Professor Miguel Gassull, Department of Gastroenterology, University Hospital Germans Trias Pujol, Barcelona, Spain. mgassull@ns.hugtip.scs.es
Journal
Gut