Dietary fatty acids and inflammation

It is commonly believed that inflammation can be reduced by lowering the dietary ratio of n-6 (linoleic acid) to n-3 polyunsaturated fatty acids as a means of lowering arachidonic acid levels in cell membranes. This review will examine this proposition. Although many pro-inflammatory molecules can be produced from arachidonic acid and this long-chain n-6 fatty acid can be produced from linoleic acid, changing dietary linoleic acid intake over a wide range does not have any significant effect on arachidonic acid levels in cell membranes, inflammation or immune functions. There are no data that show lowering dietary n-6 polyunsaturated fats reduces inflammation. In contrast, arachidonic acid levels in cell membranes and inflammatory parameters are lowered by increasing intakes of long-chain n-3 polyunsaturated fatty acids. Resolvins and protectins, both derivatives of long-chain n-3 fats, also have potential anti-inflammatory activity. In high doses, long-chain n-3 fats may have modest, beneficial effects on inflammation in rheumatoid arthritis. However, many studies have shown no effects of fish oil on inflammation parameters. The dietary n-6/n-3 ratio is not a useful measure of the inflammatory nature of a diet, though the absolute amount of dietary long-chain n-3 polyunsaturated fatty acids may be a guide.