The basic premise behind trying to improve the nutritional profile of meat fatty acids is to substitute unsaturated for saturated fatty acids.
An omega-9 fatty acid (oleic acid) is one of the main fatty acids in the Mediterranean diet, noted for its many healthful properties. Feeding oleic acid to animals, however, does not mean it will be efficiently deposited in tissues. Remember animals and people can make omega 9 fatty acids and their concentrations are regulated to maintain fluidity and melting points (i.e. if you don’t add any oleic acid to the diet, the body can make its own, and if you add oleic acid to the diet, it cuts back on the amount it makes). This mostly leaves the omega 6 and omega 3 fatty acids. Interestingly, these fatty acids have essential but opposing effects. For example, arachidonic acid (omega 6) can be used to make prostaglandins and leukotrienes that promote inflammation needed to signal the need to fight infection and repair injuries. On the other hand, EPA (omega 3) can be used to make similar signaling molecules that either are less potent or counteract the effects of signaling molecules produced from arachidonic acid. Thus, the omega 3’s can be used to balance the effects of omega 6’s, which have important implications for any disease where inflammation is involved including cardiovascular disease, asthma, arthritis, type 2 diabetes etc. And to boot, omega 3’s like DHA are needed for brain development, mental health, vision etc.
So should we be increasing omega 3’s and reducing omega 6’s? The short answer is yes. Many meats from animals finished on grain-based diets, for example corn, have omega 6 to omega 3 ratios far in excess of what is recommended. For example, omega 6 to omega 3 ratios in these types of meats can exceed 15:1 and recommendations are for ratios around 4 to 5 to 1. There are problems, however, in using ratios, as not all omega 6’s have the same effects, just as not all omega 3’s have the same effects. The longer chain and more unsaturated types of omega 6’s and 3’s typically have more potent effects than shorter chains, and although humans and animals have the capacity to convert simple omega 3 and 6 fatty acids into longer chain more potent varieties, the efficiency of conversion is not that high, particularly for omega 3’s like DHA. In addition, to further complicate things, fatty acids are selectively deposited in different tissues. Specifically, long chain omega 3’s tend to be preferentially deposited in phospholipids, and it’s more difficult to get them to accumulate in fatty tissues.