What is fish oil?
Fish oil is a rich source of the two essential omega-3 fatty acids known as EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). It is found in the fatty tissues of cold water, oily fish. It is also available in supplement form for those who eat little or no fish.
Why is it necessary?
Both omega-3 and omega-6 are essential fatty acids, which means the body cannot make them, they must be obtained from the diet. For most of human history, these fatty acids were present in the diet in roughly equal amounts. However, modern foods provide an overabundance of omega-6 fatty acids, mostly from refined vegetable oils that are used in fried food as well as snack foods, cookies and crackers. Omega-3s, conversely, are now relatively rare in American diets. The result is an imbalance of these essential fats that drives inflammation and promotes several diseases.
Compared to typical dietary intakes, regular consumption of fatty fish and/or supplemental fish oil and the omega-3 fatty acids these contain, combined with reduced intake of omega-6 fatty acids, can optimize fatty acid ratios and may help to protect mental and physical health. EPA supports heart health and DHA is a constituent of membranes of nerve cells in the brain and is thought to play an important role in normal brain development and function. Research indicates omega-3s reduce inflammation, and may in turn help reduce the risk and symptoms of a variety of disorders influenced by inflammation. These may include heart attack, stroke, several forms of cancer and autoimmune diseases such as rheumatoid arthritis.
What are the signs of a deficiency?
The average American diet is universally lacking in omega-3's. Low levels of omega-3 fatty acids may play a role in the health conditions noted above, so the development of any of those conditions may indicate a deficiency. Other signs of possible deficiency include excessive thirst, frequent urination, and dry hair and skin.
How much, and what kind, does an adult need?
Dr. Weil recommends eating oily fleshed, wild caught, cold water fish 2-3 times per week. If you use fish oil capsules, he recommends taking a product that provides 700 to 1,000 mg of EPA and 200 to 500 mg of DHA daily in the smallest number of pills. If you use liquid fish oil, find one that provides these amounts in the fewest teaspoons. Pregnant women in particular should be sure to supplement, as adequate supplies of omega-3 fatty acids are crucial to optimal brain and nervous system development in the fetus. When choosing a supplement, look for one derived from molecularly distilled fish oils - these are naturally high in both EPA and DHA and low in contaminants. Also choose a supplement brand that has been independently tested and guaranteed to be free of heavy metals such as mercury and lead, and other environmental toxins including polychlorinated biphenyls, also known as PCBs.
How much does a child need?
Fish oil has been used at one to three grams daily to help alleviate the symptoms of ADHD in children, but Dr. Weil believes the evidence is clear that all children can benefit from eating cold-water, oily fish at least twice weekly or from supplementing with one gram of fish oil daily. Effective doses are not clearly established, so consult your pediatrician before giving children fish oil supplements.
How do you get enough from foods?
Oily fleshed, cold water fish such as wild Alaskan salmon, mackerel, sardines, herring and black cod are the best sources of fish oil.
Are there any risks associated with too much?
Very large intakes of fish oil/omega-3 fatty acids (termed "Eskimo amounts" by the National Institutes of Health, referring to diets that consist almost exclusively of fish) may increase the risk of hemorrhagic stroke, and have been associated with nosebleed and blood in the urine.
Are there any other special considerations?
Because they can affect blood clotting, use fish oil supplements cautiously if you're taking any anticoagulant drugs such as Coumadin (warfarin), have had a hemorrhagic stroke, or are scheduled for surgery. People with allergies to fish should avoid fish-derived omega-3 capsules. Fish flesh may contain mercury, so pregnant and breastfeeding women and children should take care to eat species of fish that are low on the food chain and relatively free of contaminants. Dr. Weil particularly recommends sardines, as they are both relatively mercury-free and abundant.
Updated by: Andrew Weil, M.D., and Brian Becker, M.D., on January 10, 2013
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