Omega-3 fatty acids are a class of essential polyunsaturated fatty acids with the double bond in the third carbon position from the methyl terminal (hence the use of “3” in their description). Foods high in omega-3-fatty acids include salmon, halibut, sardines, albacore, trout, herring, walnut, flaxseed oil, and canola oil. Other foods that contain omega-3-fatty acids include shrimp, clams, light chunk tuna, catfish, cod, and spinach.
It has been conjectured that the diet in the human environment of evolutionary adaptedness may have been rich in seafood, nuts and other sources of vegetable omega-3. This may have provided a ratio close to 1:1. An optimal ratio for cardiovascular health is thought to be 4:1 or less. The introduction of processed foods with very high ratios of omega-6 to omega-3 in the last fifty years of the 20th century has been proposed as a possible cause for heart disease being the number one cause of death in the United States at the present time and in the recent past.
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). Once eaten, the body converts ALA to EPA and DHA, the two types of omega-3 fatty acids more readily used by the body. Extensive research indicates that omega-3 fatty acids reduce inflammation and help prevent certain chronic diseases such as heart disease and arthritis. These essential fatty acids are highly concentrated in the brain and appear to be particularly important for cognitive and behavioral function. In fact, infants who do not get enough omega-3 fatty acids from their mothers during pregnancy are at risk for developing vision and nerve problems.
BENEFITS OF OMEGA 3 FATTY ACIDS
Scientists made one of the first associations between omega-3s and human health while studying the Inuit (Eskimo) people of Greenland in the 1970s. As a group, the Inuit suffered far less from certain diseases (coronary heart disease, rheumatoid arthritis, diabetes mellitus, psoriasis) than their European counterparts. Yet their diet was very high in fat from eating whale, seal, and salmon. Eventually researchers realized that these foods were all rich in omega-3 fatty acids, which provided real disease-countering benefits.
Those who follow a Mediterranean-style diet tend to have higher HDL (“good”) cholesterol levels. Similar to those who follow a Mediterranean diet, Inuit Eskimos, who consume high amounts of omega-3 fatty acids from fatty fish, also tend to have increased HDL cholesterol and decreased triglycerides (fatty material that circulates in the blood). In addition, fish oil supplements containing EPA and DHA have been shown to reduce LDL (“bad”) cholesterol and triglycerides. Finally, walnuts (which are rich in ALA) have been shown to lower total cholesterol and triglycerides in people with high cholesterol
Diets high in omega-3 fatty acids (such as fish oils) have been shown to increase survival in people with autoimmune diseases. This is probably because the omega-3s help the arteries–as well as many other parts of the body–stay inflammation free. EPA and DHA are successful at this because they can be converted into natural anti-inflammatory substances called prostaglandins and leukotrienes, compounds that help decrease inflammation and pain.
People with diabetes tend to have high triglyceride and low HDL levels. Omega-3 fatty acids from fish oil can help lower triglycerides and raise HDL, so people with diabetes may benefit from eating foods or taking supplements that contain DHA and EPA. ALA (from flaxseed, for example) may not have the same benefit as DHA and EPA because some people with diabetes lack the ability to efficiently convert ALA to a form of omega-3 fatty acids that the body can use readily.
A recent study in the Journal of the Americal Medical Association found that women who ate five or more portions of fish every week cut their risk of having a certain type of stroke by one-third, compared to women who ate fish once a month or less.
It is thought this is because omega-3 fatty acids in oily fish make the blood less likely to clot.
People who do not get enough omega-3 fatty acids or do not maintain a healthy balance of omega-3 to omega-6 fatty acids in their diet may be at an increased risk for depression. The omega-3 fatty acids are important components of nerve cell membranes. They help nerve cells communicate with each other, which is an essential step in maintaining good mental health.
Omega-3 fatty acid, may protect against the accumulation of a protein believed to be linked to Alzheimer’s disease, according to the results of a new animal study published in the March 2005 issue of The Journal of Neuroscience. This study specifically investigated one particular kind of omega 3 fatty acids – DHA Docosahexaenoic acid.
There is no established recommended daily intake for omega-3s, but a healthy diet containing significant amounts of foods rich in this essential fatty acid is clearly wise. By increasing your intake of omega-3 fatty acids, you will naturally bring the ratio of omega-3 and omega-6 fatty acids back into a healthier, 2-1 or (optimally) 1-1 balance.