Omega-3 and omega-6 fatty acids, also called long chain polyunsaturated fatty acids (LCPUFAs), are essential to good health. They are critical in the construction of the cell membranes of tissue in the nervous system and the inflammatory and immune responses of the body. Additionally, they help stimulate skin and hair growth, maintain bone health, regulate metabolism, and maintain the reproductive system.
These essential fatty acids can be found in abundance in fish oil. But the human body can also convert them from “short chain” precursors, linolenic acids, found in plants. This conversion is an inefficient process, so fish oil supplementation is often recommended, as it is easier for the body to obtain omega-3 and omega-6 through direct consumption.
The rate of the creation of omega-3 and omega-6 from plants is determined by the FADS genes. The FADS1 gene comes in two variants, one that synthesizes LCPUFAs more efficiently from linolenic acids, and another that creates omega-3 and omega-6 less efficiently. “High synthesis” and “low synthesis” variants. If you carry a high synthesis variant you convert plants you eat into omega-3 and omega-6 much more efficiently than if you carry low synthesis variant.
A map of the distribution of high and low synthesis variants across the world shows an interesting pattern: areas of the world habitually or historically vegetarian seem to have higher proportions of the high synthesis variant. India. In contrast, populations like the Inuit of Greenland seem to have the low synthesis variant. Unlike Indians, Inuit get large amounts of omega-3 and omega-6 from the fish they consume.
Ancient DNA analysis of samples from Europe across tens of thousands of years has shown that the longer modern humans occupied the continent, the higher the frequency of the low synthesis variant was. Then, after the end of the Ice Age the first farmers arrived, and the frequency of the high synthesis variant began to go up. What was the change? The simplest answer is that the people living in Europe shifted from a diet high in omega-3 and omega-6 to one mostly relying upon grains, which would necessitate synthesis of these essential fatty acids.
Unlike some genetic variations, the ones that determine whether one synthesizes omega-3 and omega-6 at a high or low rate seem to be old alternative states. And in modern populations there are some people who carry both variations, even though the proportions may differ. This is a testament to human omnivorous habits and our need to adapt to different nutritional sources as they come along. Variation at the FADS1 reflects the protean and flexible nature of human cultures and lifestyles across continents and tends of thousands of years.
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Originally Posted by Nik
