Polyunsaturated fats is fat that consists of triglycerides containing significant amounts of polyunsaturated fatty acids (PUFA) which are fatty acids that contain more than one double bond in their backbone. This class includes many important compounds, such as essential fatty acids. The essential fatty acids are all omega-3 and omega -6 fatty acids.

Polyunsaturated fat can be found mostly in nuts, seeds, fish, algae, leafy greens, and krill. The Omega-3 fatty acids have a double bond three carbons away from the methyl carbon, whereas omega-6 fatty acids have a double bond six carbons away from the methyl carbon. The nutritional aspects of polyunsaturated fats are of highest concern, In preliminary research, omega-3 fatty acids in algal oil, fish oil, fish and seafood have been shown to lower the risk of heart attacks. Ongoing research indicates that omega-6 fatty acids in sunflower oil and safflower oil may also reduce the risk of cardiovascular disease. Among n-3 fatty acids [Omega-3], neither long-chain nor short-chain forms were consistently associated with breast cancer risk. High levels of docosahexaenoic acid (DHA), however, the most abundant n-3 PUFA [Omega-3] in erythrocyte (red blood cell) membranes, were associated with a reduced risk of breast cancer. The DHA obtained through the consumption of polyunsaturated fatty acids is positively associated with cognitive and behavioral performance. In addition DHA is vital for the grey matter structure of the human brain, as well as retinal stimulation and neurotransmission. Dietary intake of polyunsaturated fatty acids has been shown in preliminary studies to decrease the risk of developing amyotrophic lateral sclerosis.

Relation to cancer:

A 2010 study of 3,081 women suffering from breast cancer was done to research the effects of polyunsaturated fats on breast cancer. It demonstrated that the consumption of high amounts of long chain omega-3 polyunsaturated fats from food produced a 25% reduced risk of additional breast cancer events. These women were also shown to have reduced risk of “all-cause mortality.” One study in mice has shown that consuming high amounts of polyunsaturated fat may increase the risk of metastasis in cancer patients. The new findings support earlier evidence from other research that consuming high amounts of polyunsaturated fat may increase the risk of cancer spreading. The propensity for polyunsaturated fats to oxidize is another possible risk factor. Studies on animals have shown a link between polyunsaturated fat and the incidence of tumours. It is advised that the level of polyunsaturated fats in the diet be regulated though the effect on health might be considered by some to be more beneficial than harmful, due to the supposed cholesterol lowering effects of unsaturated fats compared to saturated fats. However, monounsaturated fats have also been posited to lead to lower cholesterol levels; and it is no longer clear that saturated fats actually cause elevated blood cholesterol levels.