EFFECT OF LOW-LEVEL FLAXSEED SUPPLEMENTATION ON THE FATTY-ACID COMPOSITION OF MAMMARY-GLANDS AND TUMORS IN RATS

The high alpha-linolenic acid (ALA; C18:3n-3) content of flaxseed oil and the observed protective effects of omega-3 fatty acids on cancer have led to the hypothesis that the fatty acid composition of flaxseed may render it protective against cancer. Previous studies have suggested that supplementation of a basal high-fat diet with flaxseed flour (FF) at the 5% level may influence the risk for mammary carcinogenesis but it is unknown whether the fatty acid composition of its oil (1.9% in the diet) contributed to this effect. This study showed that feeding 5% FF significantly increased the ALA and decreased the C22:5n-6 contents of the mammary glands and tumors of carcinogen- treated rats and the mammary gland of the non-carcinogen treated rats. There were small but insignificant effects on the endogenously synthesized long chain fatty acids (e.g. 16:0, 16:1n-7, 18:0 and 18:1n-9) and the longer chain unsaturated fatty acids (e.g. 20:5n-3 and 22:6n-3) derived as a result of chain elongation and desaturation of ALA. The results suggest that the fatty acid composition of the mammary tissues and tumors may be affected even at low level of flaxseed oil, and that this oil may have a role in the observed effect of flaxseed on tumorigenesis. Further studies are required to explore this possibility.