Dietary Polyunsaturated Fatty Acid Promote Peroxidation and its Possible Role in the Promotion of Cancer

Abstract

It is known that an interplay between dietary, hereditary and environmental factors initiate and/or promote cancer. Several factors associated with high risk of the development of diseases including cancer have been identified. Included in these is the amount and type of dietary fat. Circumstantial evidence provided by epidemiological studies is further supported by laboratory models that provide strong correlation between dietary fat and cancer. These studies have consistently shown that high dietary fat level of 20 percent (w/w) or 40 percent by calories promote spontaneous or induced mammary tumor growth in rats and mice (Tinsley et al., 1981, Carrol et al., 1970). Polyunsaturated fatty acid containing several double bonds are unstable molecules and are readily oxidized by non-specific and specific lipoxygenases and cyclo-oxygenase enzymes systems to yield free radicals and peroxides, which are toxic to cells. Although the peroxidation of lipids have been involved in certain forms of tissue pathology and tumor growth, the mechanism and role of these fatty acids in the development of tumors has not been completely defined. Therefore, the effect of dietary cod liver oil, a polyunsaturated fatty acid, in vivo -1-lipid peroxidation as measured by ethane exhalation was investigated.