All fats are made of various mixtures of saturated and unsaturated (monounsaturated and polyunsaturated) fatty acids. All fatty acids are composed of chains of carbon, hydrogen, and oxygen atoms. Fatty acids are named and numbered based on how their carbon, hydrogen, and oxygen atoms are arranged. “Omega-3”, “Omega-6”, and “Omega-9” are actually chains of unsaturated fatty acids categorized based on where the double bond between two carbon atoms occurs. Omega-3, omega-6, and omega-9 have a carbon–carbon double bond in the #3 position, the #6 position, and the #9 position of their carbon chains, respectively.
Omega-3 fatty acids are extremely important to health because they help suppress inflammation, an underlying cause of many diseases. There are a number of omega-3 fatty acids. They can be categorized according to short chain or long chain configurations. One important short chain omega-3 fatty acid is alpha linolenic acid (ALA). It is essential to health; however, our bodies cannot make it, so we must get this fatty acid from our diets. It is a nutrient most Americans do not get enough of as relatively few foods are good sources. Canola and soybean oils are two widely available dietary sources of essential ALA so their inclusion in the daily diet is healthful. Longer chain omega-3’s are found in fatty fish, which also have health benefits.
Omega-6 fatty acids are also essential to health and are nutrients that our bodies cannot make. The most familiar omega-6 fatty acid is called linoleic acid (LA). Many oils contain omega-6 fatty acids, including safflower, sunflower, soybean, corn, cottonseed, and peanut oils so it is much easier to get the amount needed through our daily diet. There has been some debate regarding the importance of a balanced ratio of omega-6 to omega-3 fatty acids in the diet, but others feel that it is the absolute amounts of each fatty acid in the diet that matters. The current recommendation for omega-6 fatty acid intake is 5-10% of total calories.
Omega-9 fatty acids are found in various vegetable oils and animal fats. Unlike omega-3 and omega-6 fatty acids, they are not essential, but they too are important to health. Oleic acid is one of the main omega-9 fatty acids, and emerging evidence is showing that it may be important in metabolism and weight regulation. Oleic acid is the main component of olive oil, as well as, some of the new generation, heat stable oils, including high-oleic canola and sunflower oils. Another term for high-oleic oils is Omega-9 oils. Omega-9 oils refer to a category of oils that have over 70% oleic acid and less than 3% linolenic (ALA).
When it comes to frying, the fatty acid composition of the oil determines how well it stands up to the high heat of frying. Oils high in oleic acid are very heat stable. Omega-3 fatty acids are not very heat stable however they impart an important flavor profile to the oil so when there is just enough (above 1% or so), taste perception of the cooked food product is improved. New generation, low linolenic (ALA) soy oils also have enhanced heat stability and improved frying performance.