3 February 2000
by Kate Melville
In our never-ending quest to bring you important health-related science information we present the following.
One hundred rats were recently selected to take part in a trial looking at the cancer-protecting properties of dietary fats. Previous research has clearly 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.
The control groups were apparently divided into three groups with the press release stating that these were 'equal groups', but as to how they actually divided the rats into groups of thirty three and a third is a mystery.
In any event the groups were fed oil-rich diets of either:
Safflower oil containing n6 fatty acids Fish oil containing n3 fatty acids Olive oil containing n9 fatty acids
Each groups was then further subdivided, and one half given a cancer-inducing agent. Nine weeks after starting the diets each rat was assessed for evidence of the numbers of tumours, precursors to malignancy and the fatty acid content of bowel tissue.
Rats fed the safflower oil diet had more tumours and a greater number of aberrant crypt foci and polyps (precancerous tissue) than the rats on the olive and fish oil diets.
Two diets (fish and olive oil) led to a reduction in the amount of arachidonate, known to be involved in the synthesis of prostaglandin E, an inflammatory substance that has been implicated by previous research as promoting cancer formation. Interestingly rats receiving the cancer-inducing agent and the safflower diet showed significantly increased levels of prostaglandin E but not the rats given fish or olive oil.
Oleic acid is also found in poultry, beef, and other vegetable oils (e.g. sunflower seeds, corn and soybeans) but in much smaller amounts. However, other oils and fats contained in these foods actually promote cancer, so it is doubtful that oleic acid accounts for the positive properties of olive oil. (Olive oil contains 75% oleic acid.) Instead, other components of olive oil, specifically polyphenols, flavenoids, and squalene are the likely anti-cancer agents.
Whether any related information on the percentage of body fat in the three groups was also collected was not disclosed and in our almost pathologically vain societies which would be seen as worse, being obese or having cancer (sounds crazy but think about it)?
These findings were published in a journal with a wonderful title, 'Gut'!