Safety considerations of polyunsaturated fatty acids.

The n-6 and n-3 polyunsaturated fatty acids (PUFAs) are essential nutrients; intake of relatively small amounts of these fatty acids prevents nutritional deficiencies. Replacing dietary saturated fat with PUFAs may confer health gains. Experimental data support the notion that high intake of n-6 PUFAs may increase in vivo lipid peroxidation. This effect may be counteracted by dietary antioxidant supplementation. The influence of a high n-3 PUFA intake on measures of lipid peroxidation has been equivocal. In clinical trials, subjects who consumed diets rich in n-6 or n-3 PUFAs had fewer atherothrombotic endpoints than did control groups. In this report, data regarding the influence of PUFAs on lipid peroxidation as well as on cholesterol and glucose metabolism, hemostasis, and other aspects of interest are reviewed and discussed. Currently, daily intake of PUFAs as >10% of total energy is not recommended. Below this ceiling there is little evidence that high dietary intake of n-6 or n-3 PUFAs implies health risks.