|Omega-3 fatty acids are polyunsaturated fatty acids found in certain fish tissues, and in vegetable sources such as flax seeds, hemp seeds, walnuts, and canola oil. Omega-3 fatty acids are classed as essential fatty acids. Fatty acids are the major building blocks of fats and important sources of energy in the human body. Essential fatty acids (EFAs) aid the body in many ways. As
structural parts of cell membranes and the membranes of subcellular organelles, EFAs are indispensable. The term omega-3 signifies that the first double bond in the carbon backbone of the fatty acid, counting from the end opposite the acid group, occurs in the third carbon-carbon bond. They are called omega-3 fatty acids because the first double bond counting from the methyl end of the fatty acid is located at the third carbon atom.
There are three major types of omega 3 fatty acids that are ingested in foods and used by the body: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Through an inefficient enzymatic process of desaturation, ALA produces EPA (20 carbons) and DHA (22 carbons), precursors to a group of eicosanoids (prostaglandins, thromboxanes, and leukotrienes) that are anti-inflammatory, antithrombotic, antiarrhythmic, and vasodilatory. The longer chain fatty acid derivative of linoleic acid is arachidonic acid (20 carbons), which is a precursor to a different group of eicosanoids that are proinflammatory and prothrombic. ALA and linoleic acid use and compete for the same enzymes in the production of their longer chain fatty acids, EPA, and arachidonic acid. The ingestion of fish and fish oil provides EPA and DHA directly, therefore avoiding the competition for enzymes to convert ALA to EPA. Fish and fish oil are rich sources of omega-3 fatty acids, specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Alpha-linolenic acid (ALA) is an omega-3 fatty acid present in seeds and oils, green leafy vegetables, and nuts and beans (such as walnuts and soybeans).
Omega-3 fatty acid has been recognized as having health benefits, including helping to regulate blood pressure and blood lipid levels. Omega-3 fatty acids also may help to lower the risk of heart disease, help prevent cancer, and may be essential for brain development in infants. Omega-3 fatty acids lower plasma triglyceride levels, particularly in persons with hypertriglyceridemia, by inhibiting the synthesis of very-low-density lipoprotein (VLDL) cholesterol and triglycerides in the liver. Omega-3 fatty acid intake (primarily from fish), helps protect against stroke caused by plaque buildup and blood clots in the arteries that lead to the brain. People with diabetes tend to have high triglyceride and low HDL levels. Omega-3 fatty acids such as EPA help increase levels of calcium in the body, deposit calcium in the bones, and improve bone strength. Omega-3 fatty acids appear to have a dose-response hypotensive effect in patients with hypertension and have little to no effect in normotensive patients. EPA and DHA found in fish oil help reduce risk factors for heart disease including high cholesterol and high blood pressure. Consuming significant amounts of foods rich in omega-3 fatty acids appears to reduce the risk of colorectal cancer. Omega 3 fatty acids also aid in the prevention of arthritis and improve skin and hair condition.
Omega-3 fatty acids are found in certain fatty fish and vegetables. EPA and DHA are found in cold-water fish such as salmon, mackerel, halibut, sardines, and herring. ALA is found in flaxseeds, flaxseed oil, canola (rapeseed) oil, soybeans, soybean oil, pumpkin seeds, pumpkin seed oil, purslane, perilla seed oil, walnuts, and walnut oil. Larger fatty fish such as tuna also contain omega-3 in somewhat lesser amounts, but should perhaps not be eaten in great quantities due to the potential for heavy metals which accumulate up the food chain. Additionally, with the greater lifespan of larger fish, more toxic heavy metals and other contaminants may accumulate.