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Omega-3 fatty acids
Overview
Omega-3 fatty acids are considered essential fatty acids: They are necessary for human health but the body can’t make them — you have to get them through food. Omega-3 fatty acids can be found in fish, such as salmon, tuna, and halibut, other seafood including algae and krill, some plants, and nut oils. Also known as polyunsaturated fatty acids (PUFAs), omega-3 fatty acids play a crucial role in brain function, as well as normal growth and development. They have also become popular because they may reduce the risk of heart disease. The American Heart Association recommends eating fish (particularly fatty fish such as mackerel, lake trout, herring, sardines, albacore tuna, and salmon) at least 2 times a week.
Research shows that omega-3 fatty acids reduce inflammation and may help lower risk of chronic diseases such as heart disease, cancer, and arthritis. Omega-3 fatty acids are highly concentrated in the brain and appear to be important for cognitive (brain memory and performance) 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. Symptoms of omega-3 fatty acid deficiency include fatigue, poor memory, dry skin, heart problems, mood swings or depression, and poor circulation.
It is important to have the proper ratio of omega-3 and omega-6 (another essential fatty acid) in the diet. Omega-3 fatty acids help reduce inflammation, and most omega-6 fatty acids tend to promote inflammation. The typical American diet tends to contain 14 – 25 times more omega-6 fatty acids than omega-3 fatty acids, which many nutritionally oriented physicians consider to be way too high on the omega-6 side.
The Mediterranean diet, on the other hand, has a healthier balance between omega-3 and omega-6 fatty acids. Many studies have shown that people who follow this diet are less likely to develop heart disease. The Mediterranean diet emphasizes foods rich in omega-3 fatty acids, including whole grains, fresh fruits and vegetables, fish, olive oil, garlic, as well as moderate wine consumption.
Dangers[ A 2013 review concluded that that the potential for adverse events amongst older adults taking fish oil "appear mild–moderate at worst and are unlikely to be of clinical significance". Maximum intake The FDA says it is safe to take up to 3000 mg of omega-3 per day. (This is not the same as 3000 mg of fish oil. A 1000 mg pill typically has only 300 mg of omega-3; 10 such pills would equal 3000 mg of omega-3.) Dyerberg studied healthy Greenland Eskimos and found an average intake of 5700 mg of omega-3 EPA per day.
Uses
Clinical evidence is strongest for heart disease and problems that contribute to heart disease, but omega-3 fatty acids may also be used for:
High cholesterol
People who follow a Mediterranean style diet tend to have higher HDL or “good” cholesterol levels, which help promote heart health. Inuit Eskimos, who get high amounts of omega-3 fatty acids from eating fatty fish, also tend to have increased HDL cholesterol and decreased triglycerides (fats in the blood). Several studies have shown that fish oil supplements reduce triglyceride levels. Finally, walnuts (which are rich in alpha linolenic acid or ANA, which converts to omega-3s in the body) have been reported to lower total cholesterol and triglycerides in people with high cholesterol levels.
High blood pressure
Several clinical studies suggest that diets rich in omega-3 fatty acids lower blood pressure in people with hypertension. An analysis of 17 clinical studies using fish oil supplements found that taking 3 or more grams of fish oil daily may reduce blood pressure in people with untreated hypertension. Doses this high, however, should only be taken under the direction of a physician.
Heart disease
The role of omega-3 fatty acids in cardiovascular disease is well established. One of the best ways to help prevent heart disease is to eat a diet low in saturated fat and to eat foods that are rich in monounsaturated and polyunsaturated fats (including omega-3 fatty acids). Clinical evidence suggests that EPA and DHA (eicosapentaenoic acid and docosahexaenoic acid, the 2 omega-3 fatty acids found in fish oil) help reduce risk factors for heart disease, including high cholesterol and high blood pressure. Fish oil has been shown to lower levels of triglycerides (fats in the blood), and to lower the risk of death, heart attack, stroke, and abnormal heart rhythms in people who have already had a heart attack. Fish oil also appears to help prevent and treat atherosclerosis (hardening of the arteries) by slowing the development of plaque and blood clots, which can clog arteries.
Large population studies suggest that getting omega-3 fatty acids in the diet, primarily from fish, helps protect against stroke caused by plaque buildup and blood clots in the arteries that lead to the brain. Eating at least 2 servings of fish per week can reduce the risk of stroke by as much as 50%. However, high doses of fish oil and omega-3 fatty acids may increase the risk of bleeding. People who eat more than 3 grams of omega-3 fatty acids per day (equivalent to 3 servings of fish per day) may have higher risk for hemorrhagic stroke, a potentially fatal type of stroke in which an artery in the brain leaks or ruptures.
Diabetes
People with diabetes often have high triglyceride and low HDL levels. Omega-3 fatty acids from fish oil can help lower triglycerides and apoproteins (markers of diabetes), and raise HDL, so eating foods or taking fish oil supplements may help people with diabetes. Another type of omega-3 fatty acid, ALA (from flaxseed, for example) may not have the same benefit as fish oil. Some people with diabetes can’t efficiently convert ANA to a form of omega-3 fatty acids that the body can use. Also, some people with type 2 diabetes may have slight increases in fasting blood sugar when taking fish oil, so talk to your doctor to see if fish oil is right for you.
Systemic lupus erythematosus (SLE)
Several small studies suggest that EPA and fish oil may help reduce symptoms of lupus, an autoimmune condition characterized by fatigue and joint pain. However, 2 small studies found fish oil had no effect on lupus nephritis (kidney disease caused by lupus, a frequent complication of the disease).
Osteoporosis
Some studies suggest that omega-3 fatty acids may help increase levels of calcium in the body and improve bone strength, although not all results were positive. Some studies also suggest that people who don’t get enough of some essential fatty acids (particularly EPA and gamma-linolenic acid [GLA], an omega-6 fatty acid) are more likely to have bone loss than those with normal levels of these fatty acids. In a study of women over 65 with osteoporosis, those who took EPA and GLA supplements had less bone loss over 3 years than those who took placebo. Many of these women also experienced an increase in bone density.
Depression
Studies have found mixed results as to whether taking omega-3 fatty acids can help depression symptoms. Several studies have found that people who took omega-3 fatty acids in addition to prescription antidepressants had a greater improvement in symptoms than those who took antidepressants alone. Other studies show that omega-3 fatty acid intake helps protect against postpartom depression, among other benefits. However, other studies have found no benefit.
Studies are also mixed on whether omega-3 fatty acids alone have any effect on depression. Depression is a serious illness and you should not try to treat it on your own. See a doctor for help.
Bipolar disorder
In a clinical study of 30 people with bipolar disorder, those who took fish oil in addition to standard prescription treatments for bipolar disorder for 4 months experienced fewer mood swings and relapse than those who received placebo. But another 4 month long clinical study treating people with bipolar depression and rapid cycling bipolar disorder did not find that EPA helped reduce symptoms.
Schizophrenia
Preliminary clinical evidence suggests that people with schizophrenia may have an improvement in symptoms when given omega-3 fatty acids. However, a recent well designed study concluded that EPA supplements are no better than placebo in improving symptoms of this condition.
Attention deficit/hyperactivity disorder (ADHD)
Children with attention deficit/hyperactivity disorder (ADHD) may have low levels of certain essential fatty acids (including EPA and DHA). In a clinical study of nearly 100 boys, those with lower levels of omega-3 fatty acids had more learning and behavioral problems (such as temper tantrums and sleep disturbances) than boys with normal omega-3 fatty acid levels.
However, studies examining whether omega-3 fatty acids help improve symptoms of ADHD have found mixed results. A few studies have found that omega-3 fatty acids helped improve behavioral symptoms, but most were not well designed. One study that looked at DHA in addition to stimulant therapy (standard therapy for ADHD) found no effect. More research is needed, but eating foods that are high in omega-3 fatty acids is a reasonable approach for someone with ADHD.
Cognitive decline
A number of studies show that reduced intake of omega-3 fatty acids is associated with increased risk of age related cognitive decline or dementia, including Alzheimer's disease. Scientists believe the omega-3 fatty acid DHA is protective against Alzheimer's disease and dementia.
Menstrual pain
In one study of 42 women, they had less menstrual pain when they took fish oil supplements than when they took placebo.
Coloncancer
Be sure to buy omega-3 fatty acid supplements made by established companies who certify that their products are free of heavy metals such as mercury, lead, and cadmium.
If you are currently being treated with any of the following medications, you should not use omega-3 fatty acid supplements, including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and alpha-linolenic acid (ALA), without first talking to your health care provider.
