We all know about the importance of getting enough omega-3 fatty acids in our diet. However, did you hear about omega-5, omega-7 and omega-9? The fats and oils that are a normal part of our diet are actually made up of a mixture of different types of fatty acids. These fatty acid types are quite numerous and there are more than 20 different types that are found in food. Fatty acids can be saturated, mono-unsaturated and poly-unsaturated. Saturated fatty acid molecules are straight, while the mono-unsaturated fatty acid molecules have one kink and the polyunsaturated fatty acids have more than one kink, which changes their physical properties. Fatty acids are made up of a chain of carbon units. The smallest has three carbon units, and the longest have more than 22. The omega classification refers to the distance from the end of the molecule to the first kink. So, an omega-3 fatty acid will have the first kink three carbon units from the end of the molecule.
Apart from the famous omega-3s, there are other odd fatty acids, each with their own health properties. The odd omegas are not considered to be essential fatty acids like the long chain omega-3s and 6s yet may still have important benefits. Let’s see what is going on with the odd omegas!
The celebrities of the fatty acid world, the omega-3 fatty acid alpha-linolenic acid is classed as an essential fatty acid. Everyone needs alpha-linoleic acid (ALA) in their diet to avoid deficiency, the signs of which include dry, scaly skin, hair loss and poor wound healing (1). In addition, infants and young children to the age of 2 should receive the omega-3 docosahexaenoic acid (DHA) in their diet (2) for normal eye and brain development. Some evidence shows that both docosahexaenoic acid and eicosapentaenoic acid (EPA) are important in the healthy diet of adults (2). Diets rich in omega-3s may contribute to chronic disease prevention (2).
The omega-5 fatty acids consist of several fatty acids found primarily in the seeds of plants. For example, the seeds of the snake gourd, a tropical vegetable that produces a snake-like fruit more than one meter long, contain several omega-5 fatty acids such as the alpha- and beta-eleostearic acids, and punicic acid. Punicic acid is also found in the seeds of pomegranates. Laboratory studies show that punicic acid is an antioxidant (3). The omega-5s also are being studied for their role in breast cancer (4, 5).
Omega-7 fatty acids are found in the seeds of plants and in dairy products. The omega-7 fatty acid palmitoleic acid is found in macadamia nuts and avocadoes, while vaccenic and rumenic acid come from milk, cheese and butter. Diets rich in macadamia nuts have been shown in clinical studies to have beneficial effects on the risk of cardiovascular disease, for example by reducing levels of “bad” cholesterol (6). Laboratory studies have also identified effects on the immune system that point to potential involvement of omega-7s in several chronic diseases (7).
Major sources of omega-9 fatty acids in the diet include olive oil, with its high oleic acid content, and erucic acid from canola and other oilseeds. The omega-9 fatty acids are all monounsaturated, and therefore heart healthy. In particular, oleic acid has been identified as an important contributor to the cardiovascular benefits of the Mediterranean diet (8). A review summarizes that oleic acid can improve cardiovascular disease risk markers (9). For example, triglycerides from oleic-acid rich olive oil are cleared more quickly from the blood, potentially affecting the risk of cardiovascular disease (9). Certain fatty acids accumulate in the brain, and there is some interest in whether particular fatty acids can affect cognition. In a study performed in mice with a temporary memory impairment, erucic acid was able to enhance memory due to effects on the hippocampus (10).
The Odd Omegas
While they aren’t essential, the odd omegas have plenty going on to attract the attention of nutrition and health researchers. They have antioxidant action, may be good for the heart, and some research shows potential in cancer prevention and cognition. Keep an eye on the news for the latest research involving the odd omegas.
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