All About The Omega Fats
- Apr 19, 2015
- 4 min read
We've all heard about "getting in your omega fats." But, why are these fats so good for us and why are they constantly being pushed as supplements?
Fats, or lipids, are molecules composed of glycerol and fatty acids. Fatty acids are chains of carbon and hydrogen that form "tails" on the lipids and connect to the glycerol. The orientation of the carbons and hydrogens on the fatty acid tails determines if a fat is a liquid or a solid at room temperature. The more "kinks" in the fatty acid tail caused by fewer hydrogens means that the molecules are less able to fit together tightly which caused a fat to be liquid. Solid = saturated. Liquid = unsaturated. This is where the term "hydrogenation" comes from. Fats that are "hydrogenated" are made to be more solid at room temperature. A good comparison is to compare butter and oil at room temperature. Butter is mostly saturated fat so it is solid at room temperature while oil is mostly unsaturated fat so it's liquid. Trans fats are unsaturated fats that have been "partially hydrogenated" to be solid at room temperature.
So where do the Omega fatty acids fit in? Omega-6 and Omega-3 refer to the place where the kink occurs in the fatty acid tail. Omega fatty acids are Essential Fatty Acids (EFAs), meaning that they cannot be made in the body. Most lipids can be made by the body from fats that are eaten and from fat stored in the body. Since the body cannot make the omega fats, they must come from the diet. Once the body has the "parent fatty acid" in each category, it can convert that to the other fatty acids essential to the human body. The parent fatty acid in the Omega-6 family is Linoleic Acid (LA) which is eventually converted to Arachidonic Acid (AA) and for Omega-3 is Alpha Linolenic Acid (ALA) which is converted to Eicosapentaeonic Acid (EPA) and Docosahexaenoic Acid (DHA). What a mouthful! The conversion rates from ALA to EPA and DHA is rather inefficient, so it is recommended to get these from additional sources.
Why are these EFAs so important? EFAs have important functions in the body. Both Omega-6 and Omega-3fatty acids are important in the structures of cell membranes, especially the cells of the eyes. DHA, in particular, is found in very high concentrations in the retina of the eye. DHA has been shown to be important in the development of the retina and plays an important role in the formation of rhodopsin, a compound that converts light in the eye to send images to the brain. DHA and AA are also found in high concentrations in the brain, making them important for nerve function.
Omega fatty acids are also precursors to chemical messengers called eicosanoids. Eicosanoids play a role in immune and inflammatory responses. When injury happens, hormones and other immune responses signal for AA and EPA to be released from cell membranes to make eicosanoids. These stimulate inflammation, a positive response to injury as it leads to healing. It is not accurate to say that all inflammation is bad, it is actually a part of the healing process. However, being in a state on constant inflammation such as in heart disease and obesity leads to blood vessel damage and other conditions. Eicosanoids made from EPA, an Omega-3 fatty acid are less inflammatory than those from AA, an Omega-6 fatty acid. This is not to say that Omega-6 fatty acids cause inflammation and Omega-3s are anti-inflammatory. But, if one consumes too many Omega-6 fatty acids, the balance is tipped more towards the inflammtory side. So consuming more Omega-3s would be more anti-inflammatory.
Below is a summary of current research surrounding Omega fatty acids on health:
A 2009 study by the American Heart Association found that 5-10% of calories from Omega-6 fatty acids is associated with a lower risk of cardiovascular disease. However, with too high of an intake, the risk of death was increased. Replacing saturated fats with LA reduced the risk even further and lowered the total and LDL cholesterol levels.
There is increasing evidence that EPA and DHA may decrease the risk for heart disease by: preventing arrhythmias that may lead to sudden death, decreasing the risk for clots which may cause stroke or heart attack, lowering blood pressure, decreasing serum triglyceride levels, slowing the growth of plaque, improving blood vessel function, and decreasing inflammation. In spite of this, clinical trials have not yet shown significant effects.
Some studies have indicated that high intake of fish lowers the risk for impaired congitive functin, Alzheimer's and dementia. In other studies, DHA appears to the be most effective.
In diabetics, increased intakes of EPA and DHA may be beneficial especially in those with elevated triglycerides and a history of heart attack as studies have shown that Omega-3 supplementation may reduce triglyceride levels. It has not been shown to improve blood sugar control, fasting blood glucose, Hgb A1c, or total cholesterol levels.
A 2012 study found that fish oil supplementation moderately improved symptoms of Rheumatoid Arthritis.
There is no conclusive evidence to show that Omega-3s can improve or prevent asthma. Studies have been inconclusive and inconsistent.
Sources of Omega-6s:
Sources of ALA:
Sources of EPA and DHA:
Advice on supplements: choose a fish oil supplement that is "enteric coated." This will reduce the occurrence of fishy burps.
Don't like fish or allergic to fish? You can buy flaxseeds and grind them in a food processor to get a good source of ALA, which your body will break down to EPA and DHA. The seeds need to be ground to get to the fats. Or you can buy flaxseed oil itself. Flaxseed has a nutty flavor.
Sources:
Mahan LK, Escott-Stump S, Raymond JL. Krause's Food & the Nutrition Care Process. St. Louis: Elsevier Saunders; 2012: 40-41, 1138-1139.
Higdon, J. Essential Fatty Acids. Linus Pauling Institute: Micronutrient Information Center. 2003. Available at: http://lpi.oregonstate.edu/mic/other-nutrients/essential-fatty-acids#biological-activities. Updated 2014. Accessed April 19, 2015.
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