MUFAs (especially oleic acid) have been found to lower the incidence of insulin resistance; PUFAs (especially large amounts of arachidonic acid) and SFAs (such as arachidic acid) increased it. These ratios can be indexed in the phospholipids of human skeletal muscle and in other tissues as well. This relationship between dietary fats and insulin resistance is presumed secondary to the relationship between insulin resistance and inflammation, which is partially modulated by dietary fat ratios (omega−3/6/9) with both omega−3 and −9 thought to be anti-inflammatory, and omega−6 pro-inflammatory (as well as by numerous other dietary components, particularly polyphenols and exercise, with both of these anti-inflammatory). Although both pro- and anti-inflammatory types of fat are biologically necessary, fat dietary ratios in most US diets are skewed towards omega−6, with subsequent disinhibition of inflammation and potentiation of insulin resistance. This is contrary to the suggestion that polyunsaturated fats are shown to be protective against insulin resistance.