Fatty acids cancer risk factor

The relationship between diet and cancer risk is extremely complex (7). Factors that appear to enhance carcinogenesis under one set of conditions may have no effect or even inhibit carcinogenesis under different conditions (2). The link between dietary fat and cancer is complicated by many factors, in particular total calorie intake and fatty acid composition (2). Among the fatty acids that comprise lipid, only linoleic acid is clearly linked to the enhancement of carcinogenesis in rat manunary gland (5), pancreas (4) and colon (5). 

Evidence from well-conducted epidemiological studies does not support any meaningful associations between the intake of total fat, fat type or individual fatty acids and the risk of colon, breast or prostate cancer. Final proof of a null effect should come from randomized clinical trials. However, such trials seem unlikely because initiation of tumors may occur early in life, whereas the clinical symptoms arise late in life. The cost of appropriate trials would be prohibitive. Further advances, however, may come from improved dietary assessment and a better understanding of, and adjustment for, confounding factors in epidemiological studies. 

The combination of n-3 polyunsaturated fatty acids with PS is having an emerging interest it has been reported that it is effective in reducing the levels of inflammation markers [38, 46] and cardiovascular risk factors including total cholesterol and triglyceride concentrations, pro-aggregatory factors, eicosanoid, and thromboxane A2 levels [47]. Moreover, MicaUef et al. [38] estimated that sunola or fish oils (4.0 g day ), which are rich in n-3 fatty acids, were more efficient in reducing cancer risk when administered in combination with 2.0 g day of PS than when administered alone. 

The current North American intake of total dietary fat is about 38% of calories with approximately 13-15%, 5-7% and 16-18% of calories supplied by saturated, polyunsaturated and mono-unsaturated fatty acids, respectively (Grundy, 1989). This provides for a current P/S ratio of about 0.45. There is ample evidence that these levels of total fat, and especially saturated fat, are too high and represent significant risk factors for coronary heart disease and possibly cancer at specific sites. Various agencies (American Heart Association, 1988 National Research Council, 1989 American Cancer Association and the US Department of Agriculture, US Department of Health and Human Services, 1990 Health and Welfare Canada, 1990) have recommended that the current total fat consumption be reduced to 30% of calories, with the contribution of saturated fat not to exceed 10% of calories. Furthermore, an increase in the P/S ratio from the present value of 0.45 to a value of 1.0 is also recommended. This provides for an intake of polyunsaturated fat at 10% of calories with the last 10% of fat calories supplied by mono-unsaturated fat. It is emphasized that these recommendations are for adults and children over 2 years of age. 

Palmitoleic acid is another fatty acid that deserves a brief mention. There have been reports concerning a correlation between palmitoleic acid levels in plasma and tissues and CVD risk factors. There are claims for hypocholesterolemic and hypo-glyceridemic activities, enhancement of HDL cholesterol and depression of LDL cholesterol levels, reduction of stroke incidence, and protection against certain cancers in animal models (Yang, Gunstone, and Kallio, 2003). However, the amount of data is limited and further investigations of these effects are required. 

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