Fat is a general term that describes two important dietary substances, triglycerides (stored fat) and phospholipids (structural fats). Triglycerides are what we think of when we hear the term "fat," or when we talk about oils from nuts and seeds, as well as what makes up body fat from land and sea animals.
Phospholipids are more hidden, making up the membranes that encase all cells in nature and all the organelles that lie within the cells.
Regardless of their diversity, all fats are made of the same components. Three fatty acids, the chains of carbon atoms that give different fats their different characteristics, are connected to half a sugar molecule to make a triglyceride (95 percent of dietary fat). Chain lengths range from four to 22 carbons or more, with 18 being the most common.
Carbon atoms are unique in that they can form four bonds, share electrons with four different elements. This versatility allows carbon to form a seemingly endless variety of compounds, such as proteins, fats, carbohydrates, vitamins and the nucleotides that make up DNA. Carbon can even form double bonds, which are stronger and give the molecule a more defined shape. In the case of fatty acids, double bonds create a kink or bend in the fatty acid chain.
Counting carbons from the omega end of the fatty acid chain gives the location of the double bonds. For example, in omega-9 fatty acids, the first double bond is in the number 9 position, meaning it links carbons 9 and 10 together, placing a bend in the molecule at that point. A typical 18-carbon omega-9 fatty acid will have only one double bond. (Any double bond marks that fatty acid as unsaturated.)
Saturated fatty acids have no double bonds, and thus are relatively straight. An 18-carbon saturated fatty acid called stearic acid is found in beef fat. The 18-carbon omega-9 fatty acid is commonly called oleic acid, the fatty acid dominant in olive oil and the nuts mentioned above. Since oleic acid has only one double bond, it’s referred to as a monounsaturated fatty acid.
Melting point changes (when oil turns from liquid oil to solid fat) are a result of shape changes in the fatty acids. And that’s where the terminology comes in - omega-9, omega-6, omega-3 etc. The free end of the fatty acid chains are termed "omega" in chemistry.
Omega-6 and omega-3 fatty acids have their first double bond in the number six and three positions, respectively. Placing double bonds in these positions can only be done by plants, which makes these two classes of fatty acids "essential" in terms of diet since they have to be ingested. A typical 18-carbon omega-6 fatty acid has two double bonds (one in the No. 6 position and one in the No. 9 position), while a typical 18-carbon omega 3 fatty acid has three double bonds (Nos. 3, 6 and 9).
The more double bonds, the more bent the fatty acid. The more bent the fatty acid, the more space it takes up; and the more space it occupies, the lower the melting point. This is why fats rich in saturated fatty acids are solid at room temperature and fats rich in unsaturated fatty acids are liquid oil.
All fats are mixtures of many fatty acids, both saturated and unsaturated. The typical omega-3 fatty acids found in fish are longer and more bent than the omega-3 fatty acids found in plants. That’s because the fish modifies the omega-3 fatty acids they obtain from eating algae, or from eating fish that eat algae. This is a critical adaptation for fish living in very cold water. The highly bent fatty acids keep the membranes from freezing.
Oleic acid received its reputation as a beneficial fatty acid because of studies showing that it could lower LDL cholesterol, the form connected by some studies to increased risk of cardiovascular disease, without lowering HDL cholesterol. Due to the high intake of olive oil in the Mediterranean area, it’s an important part of the Mediterranean diet.
Omega-9 fatty acids, however, are not essential. Your body can make them, along with saturated fatty acids, from any excess calories. One way to make oleic acid is to simply insert a double bond into the No. 9 position of stearic acid. In fact, a significant portion of the stearic acid from beef fat is converted to oleic acid, which is why beef fat generally doesn’t raise blood cholesterol.
The modern, "westernized" diet is rich in fat (well over 30 percent of calories), particularly saturated fatty acids due to the intake of animal foods (including dairy fats) and tropical oils (coconut and palm). It also is rich in omega-6 fatty acids, due to the high intake of corn and soy oils, compared to omega-3 fatty acids. This has many nutritionists worried because omega-6 fatty acids tend to be pro-inflammatory, compared to omega-3 fatty acids, which have a reputation of being anti-inflammatory. Omega-9 fatty acids tend to be neutral. However, recent research is pointing to health benefits associated with omega-9s.
Canola oil can be a rich source of omega-9. It has a naturally ultra-low level of saturated fatty acids. Most omega-9 oils are derived from Nexera canola and sunflower seeds developed by Dow AgroSciences. Nexera seeds were developed through natural plant breeding without the use of genetic modification.
There's a fairly long list of suppliers of omega-9 oils: ADM, Bunge, LDM Foods, Oilseeds Intl., Richardson, Stratas Foods, Ventura and Viterra, from the Dow AgroSciences website, plus Cargill.
Viterra, Ste. Agathe, Manitoba, for instance, markets n omega-9 canola oil under the name "verraUltra 9." It's a high-oleic, non-GMO, expeller-pressed canola oil designed to meet many of the needs of health-conscious consumers. The zero-trans fat, kosher-certified oil is advertised as "free of flavor characteristics that would detract from the target food."
In a 2011 article published in the British Journal of Nutrition, the effect of high-oleic canola oil on plasma lipids was described. The high-oleic canola oil was found to lower total cholesterol and LDL cholesterol without affecting HDL cholesterol. Moreover, inflammatory markers were not increased and the addition of flax oil to the canola oil caused reduction in triglycerides and inflammatory markers.
The United Soybean Board and its Qualisoy Inc. cooperative also have begun providing food processors zero-trans fat, kosher-certified high-oleic omega-9 soybean oils that feature "increased functionality across multiple applications and meet nutrition needs consumers demand." United Soybean plans to invest $60 million over the next five years to "quickly expand seed production of high oleic soybean varieties across a wide geography" and to market high-oleic soybean oils to "food companies and other stakeholders." They anticipate having 9 billion lbs. of high-oleic soybean oil available by 2023 to meet global demand.
Olive oil is not only popular but of significant health benefit in the diet. Fresh pressed olive oil is rich in phenolic acids that act as highly effective antioxidants. Avocados and various nuts are whole foods that contain a variety of micronutrients along with beneficial phytochemicals. It has become clear that in looking at the benefits of omega oils to human health, more than simply omega-3s should be considered.