Omega-3 and Omega-6 Fatty Acids Provide Health Benefits Throughout Life
With the meeting of the 10th Congress of the International Society for the Study of Fatty Acids & Lipids beginning from May 26, 2012, in Vancouver, Canada, where scientists from academia and government, and health professionals would interact, we will get to learn more about the cutting edge science related to biology of fatty acids.
So, what are fatty acids basically? Chemically, they are carboxylic acid with long hydrocarbon chains. Literally, they are fats that are important source of fuel to the cells as they break down into ATP providing energy to the heart and skeletal muscle.
Fatty acids can either be saturated (SFA) or unsaturated. Omega-3 fatty acids [that includes EPA (eicosapentaenoic acid), DHA (docosahexaenoic acid), and ALA (alpha-linolenic acid)] and omega-6 fatty acids are considered essential polyunsaturated fatty acids (PUFA) because they are required by our body to synthesize prostaglandins and other physiological regulators. Health benefits of these fatty acids, especially omega-3, include reducing inflammation as well as lowering the risk of chronic diseases such as cardiovascular disease (CVD), coronary heart disease (CHD), cancer, diabetes, high cholesterol, and arthritis. They are also important for cognitive and behavioral functions. Studies have found low levels of omega-3 may cause disorders such as attention-deficit hyperkinetic disorder (ADHD), bipolar disorder, schizophrenia, and depression.
A recent review study published in the journal Advances in Nutrition, summed up the health benefits of omega-3 as 'The omega-3 PUFA EPA and DHA are important throughout life and are a dietary necessity found predominantly in fish and fish-oil supplements. The omega-3 fatty acids EPA and DHA are essential for proper fetal development, and supplementation during pregnancy has also been linked to decreased immune responses in infants including decreased incidence of allergies in infants. Omega-3 fatty acid consumption has been associated with improved cardiovascular function in terms of anti-inflammatory properties, and reduced major coronary events'.
Along with omega-3, omega-6 fatty acids help with brain functions. They also look after the bone health, regulate metabolism, and stimulate hair and skin growth. Linoleic acid (LA), an omega-6, is amongst the most important essential fatty acids. LA gets converted to gamma-linoleic acid (GLA) and then to arachidonic acid (AA) in the body. GLA is thought to actually reduce inflammation. Omega-6 fatty acids, especially GLA, is useful for health conditions such as ADHD, allergies, high blood pressure, diabetic neuropathy, rheumatoid arthritis, osteoporosis, menopausal symptoms, and premenstrual syndrome (PMS).
In short, essential fatty acids such as omega-3 and omega-6 are indispensable for normal growth and development and they provide health benefits throughout life. Incidentally, the body cannot make these essential fatty acids. So, these must come from dietary sources.
Omega-3 fatty acids can be obtained from foods such as soybean oil, canola oil, olive oil, sunflower oil, walnut, flaxseed, and fish such as trout, herring and salmon.
Omega-6 can be obtained from vegetable oils such as soybean oil, corn oil, safflower oil and other oils mentioned above.
Normally, omega-6 is plentiful in an average diet. Rather, modern diets have more of omega-6 than omega-3 and this imbalance may promote diseases such as asthma, CVD, autoimmune and neurodegenerative diseases. According to a US study published in the journal Biomedicine and Pharmacotherapy, 'human beings evolved on a diet with a ratio of omega-6 to omega-3 essential fatty acids (EFA) of approximately 1 (that is, equal proportion) whereas in Western diets the ratio is 15/1-16.7/1'. The researchers further stated 'A ratio of 2.5/1 reduced rectal cell proliferation in patients with colorectal cancer, whereas a ratio of 4/1 with the same amount of omega-3 PUFA had no effect. The lower omega-6/omega-3 ratio in women with breast cancer was associated with decreased risk. A ratio of 2-3/1 suppressed inflammation in patients with rheumatoid arthritis, and a ratio of 5/1 had a beneficial effect on patients with asthma, whereas a ratio of 10/1 had adverse consequences. These studies indicate that the optimal ratio may vary with the disease under consideration'. Thus, a lower omega-6 / omega-3 ratio is more desirable in order to reduce the risk of chronic diseases.
There is another type of unsaturated fatty acid that is currently a hot topic for discussion - trans-fats. Natural sources of dietary trans-fats are fatty parts of meat and dairy products. Artificial trans-fats are found in foods that contain hydrogenated oil. Artificial trans-fats are found in margarines and vegetable shortenings, frozen pizzas, baked goods such as cake, cookies, pie, and also in coffee creamers, fast food, and other processed foods. According to the CDC, 'Consuming trans-fat increases low-density lipoprotein (LDL, or "bad") cholesterol contributing to the leading cause of death in the U.S. - coronary heart disease (CHD). Trans-fat may also have other adverse health effects like decreasing high-density lipoprotein (HDL, or "good") cholesterol'.
Considering these facts, the FDA required mandatory trans-fat labeling on all packaged food and a few years later some states in America have issued a trans-fat ban and a rule requiring fast food restaurants to post calorie info on menus. More recently, legislations have been passed banning trans-fats in schools as well.
The American Heart Association's Nutrition Committee recommends restricting intake of total fat to less than 25-35 percent of total calories required per day, with saturated fat intake to less than 7 percent and trans-fat intake to less than 1 percent of total daily calories. The Committee suggests that 'remaining fat should come from sources of monounsaturated and polyunsaturated fats such as nuts, seeds, fish and vegetable oils'.
Significant research studies are still being carried out to know more about the health benefits of fatty acids. In view of this, we await the results of the advances made in fatty acid and lipid research.
2. Swanson D, Block R, Mousa SA. Omega-3 fatty acids EPA and DHA: health benefits throughout life. Adv Nutr. 2012 Jan;3(1):1-7. http://advances.nutrition.org/content/3/1/1.full?sid=0bd774e3-f734-47a5-b0b4-a091a7df5719