Omega-3 fatty acids
Omega-3 fatty acids are one of two groups of fatty acids—the omega-3s and the omega-6s—that are vital to human life. The omega-3 fatty acids get their name from the fact that the molecules of which they are made contain a double bond attached to the number 3 carbon atom, counting from the end of the molecule opposite the carboxyl group, the so-called omega end of the molecule. (This system of nomenclature is just the reverse of the one used by chemists.)
The omega-3 fatty acids are called essential fatty acids (EFAs) because the body is unable to make them, but they are essential for normal growth and development. These fats must be supplied in a person’s diet.
People living in industrialized Western countries eat up to 30 times more omega-6 than omega-3 fatty acids, resulting in a relative deficiency of omega-3 fats.
Omega-6 metabolic products (inflammatory prostaglandins, thromboxanes, and leukotrienes) are formed in excessive amounts, causing allergic and inflammatory disorders and making the body more prone to heart attacks, strokes, and cancer.
Eating foods rich in omega-3 acids or taking fish oil supplements can restore the balance between the two fatty acids and can possibly reverse these disease processes.
- Heart disease and stroke
The American Heart Association (AHA) has endorsed omega-3 fatty acids as good for the heart. Omega-3 oils increase the concentration of good cholesterol (high density lipoproteins, HDL) while decreasing the concentration of bad cholesterol (lowdensity lipoproteins, LDL) and triglycerides. In addition, eating omega-3-rich food results in a moderate decrease in total cholesterol level. In one study of 38 women, flaxseed flour, which contains high amounts of omega-3 fatty acids, decreased total cholesterol level by 6.9% and LDL cholesterol by 14.7%. In addition, lipoprotein(a), which is associated with heart attacks in older women, decreased by almost 10%. Thus, omega-3 fatty acids are natural alternatives to estrogen in prevention of heart attacks in postmenopausal women.
Furthermore, omega-3 oils protect the heart by preventing blood clots or keeping other fats from injuring the arterial walls. The substances relax arteries and help to decrease constriction of arteries and thickening of blood. Hundreds of studies have shown that diets rich in omega-3 fatty acids decrease risk of heart attacks, strokes, and abnormal heart rhythms. Eskimos, who eat a lot of cold-water fish, have low rates of heart attacks and strokes, perhaps because they have thinner blood, high HDL to LDL cholesterol ratio, and less buildup of fatty deposits (plaques) in the arteries.
A number of clinical trials have shown that regular consumption of fish or fish-oil supplements can prevent sudden deaths due to abnormal heart rhythms. In the Diet and Reinfarction Trial (DART) of 2,033 men who previously suffered a heart attack, subjects who ate two to three servings of fatty fish per week had their risk of sudden cardiac death lowered by 29% compared to those who had a low fat or high fiber diet. In the Physician’s Health Study of 20,551 doctors, a 52% reduction in risk of heart attacks was observed in those who ate at least one fish meal per week compared with those who ate fish once a month or less.
Several studies have shown that eating 200 g of fatty fish or taking six to 10 capsules of fish oil daily will lower blood pressure (BP). Therefore, omega-3 can benefit patients with borderline high blood pressure. Omega-3 oils also effectively prevent hypertension in cardiac patients after transplantation.
Supplement for newborns and babies
Omega-3 fatty acids are essential for normal development of vision and brain function, especially in newborns and children. Very low birth weight preterm infants often have poor vision and motor skills, possibly because they receive less than one-third of the amount of omega-3 fatty acids outside the mother’s womb that they would have received as a fetus. Human breast milk contains the appropriate amount of omega-3 and -6 fats and is believed best for babies.
If mother’s milk is unavailable, formulas with soybean oil that provide higher amounts of omega-3 fatty acids are more beneficial than those made from cow’s milk. Even full-term babies benefit from the addition of essential fatty acids to cow-milk formulas. Studies have shown that babies given formulas supplemented with EFAs have better vision and score higher in skills and problem-solving tests compared to babies on formulas that do not contain additional EFAs.
- Rheumatoid arthritis
Because omega-3 fatty acids inhibit the action of inflammatory prostaglandins and leukotrienes, they can help control arthritis symptoms. Significant reduction in the number of tender joints and morning stiffness, as well as an increase in grip strength, have been observed in patients taking fish oil capsules. Studies have shown that patients taking fish oil supplements for rheumatoid arthritis require fewer pain medications; some are able to discontinue their nonsteroidal anti-inflammatory treatment. Despite the beneficial effects of omega-3 fats, regular antirheumatic drugs and nonsteroidal anti-inflammatory medications most likely still are required to control this chronic condition.
Some studies in laboratories have indicated that omega-3 fatty acids in fish oils may prolong life in people with autoimmune disorders such as diabetes. One study looked at substituting fish oil for corn oil in diets and found a tendency to suppress immune system dysfunction and prolong life.
- Inflammatory bowel disease
High-dose fish-oil supplements have been shown to decrease abdominal cramping, diarrhea, and pain associatedwith Crohn’s disease. In one study of 96 patients, individuals who received 4.5 g of omega-3 fatty acids required significantly less steroids to control symptoms. In another study of 78 Crohn’s disease patients, 59%of individuals who received 2.7 g of omega-3 fatty acids daily did not have any disease flare-ups for at least one year compared to 26% recurrence rate in patients who were not given fish oil. Omega-3 fatty acids also are effective in preventing reappearance of Crohn’s disease after surgery to remove sections of diseased bowel.
Taking high dose omega-3 fatty acids can reduce inflammation of the airways and reduce asthma attacks. According to Donald Rudin, the author of Omega-3 Oils, allergic disorders such as asthma may be triggered by too much omega-6 and too little omega- 3 fats in the body. Excessive amounts of omega-6 prostaglandins cause the body to produce antibodies that cause allergic reactions. Flaxseed or fish oil supplements can keep the omega-6 fats in check and decrease the inflammatory reactions associated with asthma.
- Berger’s disease (Immunoglobulin A nephropathy)
Omega-3 fats may be effective in treating this autoimmune disease, in which kidney function fails over time, with few treatment options available. In a large, randomized study of 150 patients, those who received 3 g of omega-3 fatty acids daily for two years had significantly less reduction in renal function than those treated with placebo. Therefore, omega-3 fatty acids appear to have protective effects and may stabilize renal function in these patients.
- Raynaud’s disease
There have been few studies evaluating the effects of omega-3 fatty acids in treating Raynaud’s disease; however, it appears that fish oil supplements may alleviate some blood-clotting disorders.
- Mental disorders
According to some studies, many common mental disorders, such as depression, bipolar disorder (manic-depression), attention-deficit hyperactive disorder (ADHD), anxiety, and schizophrenia, may be triggered by deficiencies of omega-3 fatty acids and/or B vitamins. The rates of depression are low in countries where people eat a lot of fish, while the rate of depression steadily rises in the United States as Americans eat increasingly more processed food and less fresh fish and vegetables containing omega-3 fats.
- Acquired immunodeficiency syndrome (AIDS)
In a study of 20 AIDS patients, those who received fish oil supplements at a dosage of 10 g of omega-3 fatty acids per day for 30 days gained more weight (2.4 kg) and significantly lowered their concentrations of tumor necrosis factor, which is believed to cause wasting in AIDS patients, compared to those who did not.
- Cancer prevention
Omega-3 fatty acids inhibit tumor growth when injected into animals. Flaxseed oil, which is a plant source of omega-3 fatty acids, has been shown to prevent cancer of the breast, colon, and prostate. The Mediterranean diet, which is heart healthy, also can decrease risk of getting cancer. Omega-3 fats, it seems, strengthen the immune systems and inhibit the inflammation and blood circulation of the tumors.
Macronutrients, such as the omega-3 fatty acids, are not assigned recommended daily allowance (RDA) levels, as are micronutrients like vitamins and minerals. However, the U.S. Food and Nutrition Board does establish adequate intake (IA) levels for macronutrients, such as the omega-3 fatty acids, including alpha linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Those recommendations differ according to age and sex and for women who are pregnant or lactating. For men over the age of 14, the AI for ALA (the only omega-3 fatty acid for which an AI exists) is 1.6 grams per day; for women in the same age range, the AI for ALA is 1.1 grams per day.
The best way to achieve this dietary requirement is by eating fatty fish two or three times a week and/or eating vegetables and oils containing omega-3 fatty acids. Omega-3 fatty acids can be found naturally in the oil of cold-water fish, such as mackerel, salmon, sardines, anchovies, and tuna, or as extracted oils from plants, such as flaxseed, canola (rapeseed), or soybean. If fish oil supplement is preferred, then one to two 1-g capsules a day is sufficient. Each 1 g fish oil capsule typically contains 180 mg of EPA and 120 mg of DHA. Vitamin E is often added to fish oil supplements to prevent spoilage and vitamin-E deficiency, which may occur with high dose fish-oil consumption. Patients should take supplements containing omega-3 fatty acids only under professional supervision to prevent an overdose, adverse reactions, or interactions with other medications. For treatment of diseases, flaxseed oil should be the first choice because it is the richest source of omega-3 fatty acids, relatively safe, and inexpensive.
The safest and most effective way to get omega-3 fatty acids is through diets of at least three fish meals a week. Fish oil or flaxseed oil supplements should be taken only under a physician’s supervision. Although fish oils can be helpful in relieving arthritic symptoms, patients still may need antiinflammatory medications to adequately control the disease. Taking any medication during pregnancy is not recommended. Women who are pregnant or breastfeeding should talk to their doctor before taking fish oil supplements or any other medications.