Results for omega-3 fatty acid
On this page:
 
Dictionary:

omega-3 fatty acid

  (ō-mĕg'ə-thrē', -mē'gə-, -mā'-) pronunciation
n.

Any of several polyunsaturated fatty acids found in leafy green vegetables, vegetable oils, and fish such as salmon and mackerel, capable of reducing serum cholesterol levels and having anticoagulant properties.


 
 
Oncology Encyclopedia: Omega-3 Fatty Acids

Definition

Essential to human health, omega-3 fatty acids are a form of polyunsaturated fats that are not made by the body and must be obtained from a person's food.

Purpose

Eating foods rich in omega-3 fatty acids is part of a healthy diet and helps people maintain their health.

Description

In recent years, a great deal of attention has been placed on the value of eating a low fat diet. In some cases, people have taken this advice to the extreme by adopting a diet that is far too low in fat or, worse yet, a diet that has no fat at all. But the truth is that not all fat is bad. Although it is true that trans and saturated fats, which are found in high amounts in red meat, butter, whole milk, and some prepackaged foods, have been shown to raise a person's total cholesterol, polyunsaturated fats can actually play a part in keeping cholesterol low. Two especially good fats are the omega-3 fatty acids and the omega-6 fatty acids, which are polyunsaturated.

Two types of omega-3 fatty acids are eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA), which are found mainly in oily cold-water fish, such as tuna, salmon, trout, herring, sardines, bass, swordfish, and mackerel. With the exception of seaweed, most plants do not contain EPA or DHA. However, alpha-linolenic acid (ALA), which is another kind of omega-3 fatty acid, is found in dark green leafy vegetables, flaxseed oil, fish oil, and canola oil, as well as nuts and beans, such as walnuts and soybeans. Enzymes in a person's body can convert ALA to EPA and DHA, which are the two kinds of omega-3 fatty acids easily utilized by the body.

Many experts agree that it is important to maintain a healthy balance between omega-3 fatty acids and omega-6 fatty acids. As Dr. Penny Kris-Etherton and her colleagues reported in their article published in the American Journal of Nutrition an over consumption of omega-6 fatty acids has resulted in an unhealthy dietary shift in the Americandiet. The authors point out that what used to be a 1:1 ratio between omega-3 and omega-6 fatty acids is now estimated to be a 10:1 ratio. This poses a problem, researchers say, because consuming some of the beneficial effects gained from omega-3 fatty acidsare negated by an over consumption of omega-6 fatty acids. For example, omega-3 fatty acids have anti-inflammatory properties, whereas omega-6 fatty acids tend to promote inflammation. Cereals, whole grain bread, margarine, and vegetable oils, such as corn, peanut, and sunflower oil, are examples of omega-6 fatty acids. In addition, people consume a lot of omega-6 fatty acid simply by eating the meat of animals that were fed grain rich in omega-6. Some experts suggest that eating one to four times more omega-6 fatty acids than omega-3 fatty acids is a reasonable ratio. In other words, as dietitians often say, the key to a healthy diet is moderation and balance.

The Health Benefits of Omega-3 Fatty Acids

There is strong evidence that omega-3 fatty acids protect a person against atherosclerosis andtherefore against heart disease and stroke, as well as abnormal heart rhythms that cause sudden cardiac death, and possibly autoimmune disorders, such as lupus and rheumatoid arthritis. In fact, Drs. Dean Ornish and Mehmet Oz, renowned heart physicians, said in a 2002 article published in O Magazine that the benefits derived from consuming the proper daily dose of omega-3 fatty acids may help to reduce sudden cardiac death by as much as 50%. In fact, in an article published by American Family Physician, Dr. Maggie Covington, a clinical assistant professor at the University of Maryland, also emphasized the value of omega-3 fatty acids with regard tocardiovascular health and referred to one of the largest clinical trials to date, the GISSI-Prevenzione Trial, to illustrate her point. In the study, 11,324 patients with coronary heart disease were divided into four groups: one group received 300 mg of vitamin E, one group received 850 mg of omega-3 fatty acids, one group received the vitamin E and fatty acids, and one group served as the control group. After a little more than three years, "The group given omega-3 fatty acids only had a 45% reduction in sudden death and a 20% reduction in all-cause mortality," as stated by Dr. Covington.

According to the American Heart Association (AHA), the ways in which omega-3 fatty acids may reduce cardiovascular disease are still being studied. However, the AHA indicates that research as shown that omega-3 fatty acids:

  • decrease the risk of arrthythmias, which can lead to sudden cardiac death
  • decrease triglyceride levels
  • decrease the growth rate of atherosclerotic plaque
  • lower blood pressure slightly

In fact, numerous studies show that a diet rich in omega-3 fatty acids not only lowers bad cholesterol, known as LDL, but also lowers triglycerides, the fatty material that circulates in the blood. Interestingly, researchers have found that the cholesterol levels of Inuit Eskimos tend to be quite good, despite the fact that they have a high fat diet. The reason for this, research has found, is that their diet is high in fatty fish, which is loaded with omega-3 fatty acids. The same has often been said about the typical Mediterranean-style diet.

Said to reduce joint inflammation, omega-3 fatty acid supplements have been the focus of many studies attempting to validate its effectiveness in treating rheumatoid arthritis. According to a large body of research in the area, omega-3 fatty acid supplements are clearly effective in reducing the symptoms associated with rheumatoid arthritis, such as joint tenderness and stiffness. In some cases, a reduction in the amount of medication needed by rheumatoid arthritis patients has been noted.

More research needs to be done to substantiate the effectiveness of omega-3 fatty acids in treating eating disorders, attention deficit disorder, and depression. Some studies have indicated, for example, that children with behavioral problems and attention deficit disorder have lower than normal amounts of omega-3 fatty acids in their bodies. However, until there is more data in these very important areas of research, a conservative approach should be taken, specially when making changes to a child's diet. Parents should to talk to their child's pediatrician to ascertain if adding more omega-3 fatty acids to their child's diet is appropriate. In addition, parents should take special care to avoid feeding their children fish high in mercury. A food list containing items rich in omega-3 fatty acids can be obtained from a licensed dietitian.

Mercury Levels and Concerns About Safety

A great deal of media attention has been focused on the high mercury levels found in some types of fish. People concerned about fish consumption and mercury levels can review public releases on the subject issued by the U. S. Food and Drug Administration and the Environmental Protection Agency. Special precautions exist for children and pregnant or breastfeeding women. They are advised to avoid shark, mackerel, swordfish, and tilefish. However, both the U.S. Food and Drug Administration and the Environmental Protection Agency emphasis the importance of dietary fish. Fish, they caution, should not be eliminated from the diet. In fact, Robert Oh, M.D., stated in his 2005 article, which was published in The Journal of the American Board of Family Practice "With the potential health benefits of fish, women of childbearing age should be encouraged to eat 1 to 2 low-mercury fish meals per week."

Other concerns regarding fish safety have also been reported. In 2004, Hites and colleagues assessed organic contaminants n salmon in an article published in Science. Their conclusion that farmed salmon had higher concentrations of polychlorinated biphenyls than wild salmon prompted public concerns and a response from the American Cancer Society. Farmed fish in Europe was found to have higher levels of mercury than farmed salmon in North and South America; however, the American Cancer Society reminded the public that the "levels of toxins Hites and his colleagues found in the farmed salmon were still below what the U. S. Food and Drug Administration, which regulates food, considers hazardous." The American Cancer Society still continues to promote a healthy, varied diet, which includes fish as a food source.

Recommended Dosage

The AHA recommends that people eat two servings of fish, such as tuna or salmon, at least twice a week. A person with coronary heart disease, according to the AHA, should consume 1 gram of omega-3 fatty acids daily through food intake, most preferably through the consumption of fatty fish. The AHA also states that "people with elevated triglycerides may need 2 to 4 grams of EPA and DHA per day provided as a supplement," which is available in liquid orcapsule form. Ground or cracked flaxseed can easily be incorporated into a person's diet by sprinkling it over salads, soup, and cereal.

Sources differ, but here are some general examples:

  • 3 ounces of pickled herring = 1.2 grams of omega-3 fatty acids
  • 3 ounces of salmon = 1.3 grams of omega-3 fatty acids
  • 3 ounces of halibut = 1.0 grams of omega-3 fatty acids
  • 3 ounces of mackerel = 1.6 grams of omega-3 fatty acids
  • 1 1/2 teaspoons of flaxseeds = 3 grams of omega-3 fatty acids

Precautions

In early 2004, the U.S. Food and Drug Administration, along with the the Environmental Protection Agency, issued a statement that women who are or may be pregnant, as well as breastfeeding mothers and children, should avoid eating some types of fish thought to contain high levels of mercury. Fish that typically contain high levels of mercury are shark, swordfish, and mackerel, whereas shrimp, canned light tuna, salmon, and catfish are generally thought to have low levels of mercury. Because many people engage in fishing as a hobby, women should be sure before they eat any fish caught by friends and family that the local stream or lake is considered low in mercury.

Conflicting information exists whether it is safe for patients with macular degeneration to take omega-3 fatty acids in supplement form. Until more data becomes available, it is better for people with macular degeneration to receive their omega-3 fatty acids from the food they eat.

Side Effects

Fish oil supplements can cause diarrhea and gas. Also, the fish oil capsules tend to have a fishy aftertaste.

Interactions

Although there are no significant drug interactions associated with eating foods containing omega-3 fatty acids, patients who are being treated with blood-thinning medications shouldn't take omega-3 fatty acid supplements without seeking the advice of their physicians. Excessive bleeding could result. For the same reason, some patients who plan to take more than 3 grams of omega-3 fatty acids in supplement form should first seek the approval of their physicians.

Resources

Periodicals

Albert, C. M., Hennekens, C. H., O'Donnell, C. J., et al. "Fish consumption and risk of sudden cardiac death." Journal of the American Medical Association 279 (1998): 23–28.

Covington, M. B. "Omega-3 Fatty Acids." American Family Physician 70 (2004): 133–140.

Harris, W. S. "N-3 fatty acids and serum lipoproteins: human studies." American Journal of Clinical Nutrition 65 (1997): 1645–1654.

Hites, R. A., Foran, J. A., Carpenter, D. O., et al. W. S. "Global assessment of organic contaminants in farmed salmon." Science 303 (1997): 226–229.

Kris-Etherton, P. M., Harris, W. S., Appel, L. J., and American Heart Association Nutrition Committee. "Fish consumption, fish oil, omega-3 fatty acids, and cardiovascular disease." Circulation 106 (2003): 2747–2757.

Kris-Etherton, P. M., Taylor, D. S., Yu-Poth, S., et al. "Polyunsaturated fatty acids in the food chain in the United States." American Journal of Clinical Nutrition 71 (2000): 1795–1885.

Oh, R. "Practical applications of fish oil (omega-3 fatty acids) in primary." The Journal of the American Board of Family Practice 18 (2005): 28–36.

Ornish, Dean and Oz, Mehmet. "Caution: Strong at Heart." O: The Oprah Magazine November 2002:163–168.

Organization

American Cancer Society. "Is Salmon Safe?" American Cancer Society 28 Jan 2004 American Camcer Society. 24 Feb 2005

American Heart Association. "American Heart Association Recommendation: Fish and Omega-3 Fatty Acids." American Heart Association 2005 American Heart Association. 22 Feb 2005

Health and Age. "Omega-3 Fatty Acids." Health and Age 2005 [cited 22 Feb 2005].

Kris-Etherton, P.M., Harris, W.S., Appel, L.J., and American Heart Association Nutrition Committee. "American Heart Association Statement: New Guidelines Focus on Fish, Fish Oil, Omega-3 Fatty Acids." American Heart Association 18 November 2002 American Heart Association. 22 Feb 2005

U.S. Food and Drug Administration. "What You Need to Know About Mercury in Fish and Shellfish." U.S. Food and Drug Administration. March 2004 U.S. Food and Drug Administration. 22 Feb 2005

—Lee Ann Paradise

 
Food and Nutrition: omega-3 fatty acids

omega-6 fatty acids, or omega-9 fatty acids ω3 fatty acidsThree series of long-chain polyunsaturated fatty acids derived respectively from linolenic, linoleic, and oleic acids. Omega (ω) or n being the position of the first double bond counting from the terminal methyl group.

 
Food and Fitness: omega-3 fatty acids

A group of unsaturated fatty acids found in some fish oils and linseed oil. Omega-3 fatty acids may change the chemistry of blood, reducing the risk of heart disease. Consumption of foods with high levels of these fatty acids may be ‘cardioprotective’ because they help to lower blood cholesterol and prevent arteries from being clogged with cholesterolrich plaques. It has been suggested that one oily-fish meal a week provides the same protection as three or more. Fish oil capsules containing omega-3 fatty acids are now on the market, but according to the American Medical Association, the capsules may not be as effective as eating fish and other oily seafood. It is possible that the fatty acids only work effectively with other components in fish that are absent from the capsules. Moreover, there is insufficient clinical research data to determine the proper dosage of the fish oils. See also cholesterol.

 
Drug Info: Fish Oil, Omega-3 Fatty Acids

Brand names: Dr. Sears® OmegaRx™, Eskimo-3®, Fish Oil, Omega-3 Fatty Acids, Lovaza™, Mega Twin EPA, Natrol® DHA Neuromins™, Natrol® Omega-3, Oleomed™ Heart, Omacor®, Omega-3 Fish Oil Concentrate, Sea-Omega® 30, Sea-Omega® 50, Sea-Omega® 70, ZonePerfect® Omega 3



Fish Oil, Omega-3 Fatty Acids capsules

What are fish oil, omega-3 fatty acids caspules?

FISH OIL, OMEGA-3 FATTY ACIDS ( Omacor® and others) are essential fats obtained from eating fish and other seafood. Only Omacor®, a prescription product, has received FDA approval to help lower triglycerides (a blood fat) in patients with high triglyceride values. The product should be used in conjunction with a diet designed to be heart-healthy.

Fish oil capsules are also often promoted to reduce heart disease risk, to help with symptoms of rheumatoid arthritis, to lower high triglyceride levels, and for many other purposes for which research is not yet substantial enough. Because supplements are still controversial and many health experts do not recommend fish oil capsules as a substitute for fish in the diet at this time. Most fish oil supplements are not officially endorsed by the FDA for any medical uses. Many different brands of fish oil capsules are available.

Fatty fish like albacore tuna, halibut, herring, mackerel, lake trout, salmon, and sardines are high in omega-3 fatty acids. These fish contain roughly 1 gram of omega-3 fatty acids per 3.5 ounces of fish. If you would like to improve your dietary intake of fish oils, many experts recommend eating up to 2 fish servings per week in the diet. Eating fish as part of a low fat diet may improve heart health and have other health benefits.

What should I tell my health care provider before I take this medicine?

It is important for you to tell your prescriber or health care professional or other health care professional that you are using fish oil, omega-3 fatty acids, particularly if you have a chronic health condition.

Talk to your health care provider BEFORE taking fish oil supplements if you have any of the following conditions:
• asthma or other lung disease
• blood vessel disease
• diabetes mellitus or high blood sugar levels
• high blood pressure
• high cholesterol
• history of heart attack or other heart disease
• inflammatory conditions such as rheumatoid arthritis or lupus
• kidney disease
• liver disease
• migraine headaches
• mood disorders like attention-deficit hyperactivity disorder, bipolar disorder or schizophrenia
• an unusual or allergic reaction to fish, seafoods or other medicines, foods, dyes, or preservatives
• pregnant or trying to get pregnant
• breast-feeding

How should I use this medicine?

Fish oil capsules should be taken orally (i.e., swallowed). Swallow capsules with water or other liquid. Taking these products with food or meals may limit stomach discomfort. Omacor® is recommended to be taken with meals. Follow the directions on the prescription or product label, or consult your health care professional for advice.

Contact your pediatrician or health care professional regarding the use of this medicine in children. Special care may be needed. Fish oil supplements should not be used in children without a prescriber's advice.

What drug(s) may interact with fish oil?

• aspirin
• clopidogrel
• cilostazol
• dalteparin, enoxaparin or other injectable blood thinners
• dipyridamole
• heparin
• herbal products like danshen, dong quai, garlic pills, ginger, ginkgo biloba, horse chestnut, willow bark, and others
• medications for high blood pressure
• ticlopidine
• warfarin

For many nutritional supplements, interactions with other medications are unknown. That is why you should always be careful when mixing fish oil supplements with traditional medications. If you take any other medications, consult with your health care professional prior to taking fish oil.

Tell your prescriber or health care professional about all other medicines you are taking, including non-prescription medicines, nutritional supplements, or herbal products. Also tell your prescriber or health care professional if you are a frequent user of drinks with caffeine or alcohol, if you smoke, or if you use illegal drugs. These may affect the way your medicine works. Check with your health care professional before stopping or starting any of your medicines.

What should I watch for while taking fish oil?

Since fish oils are derived from marine life, allergic reactions are possible. Stop using this product if you develop a rash. You may need to see your health care professional, or inform them that this occurred. Report any other unusual side effects promptly.

It may take several weeks of fish oil use before you notice an improvement in your symptoms and/or blood tests that are monitored by your prescriber. You should contact your health care professional for advice prior to prolonged use of fish oils.

Different brands of fish oil might contain different amounts of these oils so you may wish to consistently use the same brand. It is recommended that you use a brand from a reliable manufacturer. Your health care professional or pharmacist can assist you in finding a product.

If you are going to have elective surgery, you may need to stop taking this supplement before the procedure. Let your health care professional know you are taking fish oil capsules prior to scheduling the surgery.

What side effects may I notice from using fish oil?

Side effects that you should report to your prescriber or health care professional as soon as possible:
• changes in your moods or emotions
• easy bruising
• nosebleeds
• skin rash or unusual skin reaction

Side effects that usually do not require medical attention (report to your prescriber or health care professional if they continue or are bothersome):
• bad breath (fishy breath)
• belching
• diarrhea
• heartburn
• nausea
• stomach upset
• weight gain

Where can I keep my medicine?

Keep out of the reach of children.

Store at room temperature between 15—30 degrees C (59—86 degrees F). Do not freeze. Throw away any unused medicine after the expiration date.

GENERAL INFORMATION REGARDING DIETARY SUPPLEMENTS:
Dietary supplements include amino acids, vitamins, minerals, herbs, and other plant-derived substances, and extracts of these substances. Products are easy to identify as they must state 'Dietary Supplement' on the label. A 'Supplement Facts' panel is provided on the label for most products. Supplements are not drugs and are not regulated like pharmaceuticals. You should note that rigid quality control standards are not required for dietary supplements. Differences in the potency and purity of these products can occur. Scientific data to support the use of a dietary supplement for a certain condition may not be available. This product is not intended to diagnose, treat, cure or prevent any disease.

The Food and Drug Administration suggests the following to help consumers protect themselves:
• Always read product labels and follow directions.
• Look for products containing ingredients with the 'USP' notation. This indicates the manufacturer followed the standards of the US Pharmacopoeia.
• 'Natural' doesn't mean a product is safe for humans to consume.
• Supplements produced or distributed by a nationally known food or drug company are more likely to be made under tight controls as these companies have standards in place for their other products. You can write to the company or manufacturer for more information about the conditions under which the products are made.

Last updated: 12/8/2004 2:15:00 PM

Important Disclaimer: The drug information provided here is for educational purposes only. It is intended to supplement, not substitute for, the diagnosis, treatment and advice of a medical professional. This drug information does not cover all possible uses, precautions, side effects and interactions. It should not be construed to indicate that this or any drug is safe for you. Consult your medical professional for guidance before using any prescription or over the counter drugs.

 

Description

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. They are called essential fatty acids (EFAs), which the body cannot make but absolutely needs for normal growth and development. These fats must be supplied by 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 diets 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.

General Use

Heart Disease and Stroke

The American Heart Association (AHA) has endorsed omega-3 fatty acids as good for the heart. The omega-3 oils increase the concentrations of good cholesterol (high density lipoproteins, HDL) while decreasing the concentrations of bad cholesterol (triglycerides). In addition, eating omega-3-rich food will result in a moderate decrease in total cholesterol level. In a clinical 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. They not only relax arteries but also 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, possibly because they have thinner blood, high HDL to LDL cholesterol ratio, and less buildup of fatty deposits (plaques) in the arteries. Two 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, men who ate two to three servings of fatty fish a 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.

Mild Hypertension

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 pre-term 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 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.

Diabetes

Early studies in laboratories indicate that omega-3 fatty acids in fish oils might prolong life in people with automimmune disorders like diabetes. A new study looked at substituting fish oil for corn oil in diets and found a tendency to suppress immune system dysfunction and prolong life. More studies are required to prove the diet's benefits in humans.

Inflammatory Bowel Disease

High-dose fish-oil supplements have shown to decrease abdominal cramping, diarrhea, and pain associated with Crohn's disease. In one study of 96 patients, patients who received 4.5 g of omega-3 fatty acids (15 fish oil capsules) required significantly less steroids to control symptoms. In another study of 78 Crohn's disease patients, 59% of patients who received nine fish oil capsules (2.7g 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. In a clinical trial involving 50 patients, patients who received 2.7 grams of omega-3 fats as fish oil cut their rate of disease reappearance in half compared to patients receiving placebo. However, the effectiveness of omega-3 oils varies depending on the type of omega-3 oils being used, length of use, and the patient's diet.

Asthma

Taking high dose omega-3 fatty acids can reduce inflammation of the airways and reduce asthma attacks. According to Donald Rudin, the author of the book titled Omega-3 Oils, allergic disorders such as asthma may be triggered by too much omega-6 and too little omega-3 fats in our 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, or schizophrenia, may be triggered by deficiencies of omega-3 fatty acids and/or B vitamins. The rates of depression are low in countries that 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. In one study, 53% of bipolar patients on placebo (olive oil) became ill again within four months, while none of the patients who were given 9.6 g daily of omega-3 fatty acids (as fish oil) did. Supplements containing omega-3 fats also reportedly have been effective in children with ADHD precipitated by essential fatty acid deficiencies. Furthermore, a 25% decrease in schizophrenic symptoms was observed in patients receiving eicosapentanoic acid (EPA), one of the omega-3 fatty acids contained in fish oil.

A report in 2001 revealed that omega-3 fatty acids may have effects on stabilizing mood and relieving depression. As studies continue, researchers are finding it more and more evident that omega-3 fatty acids can be effective for treating depression, though they still are un-certain exactly how they work. A 2003 report linked depression to increased risk of sudden cardiac death.

Acquired Immunodeficiency Syndrome (AIDS)

In a small study of 20 AIDS patients, those who received fish oil supplement at 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.

Preparations

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. As of 2001, the U.S. Food and Nutrition Board had not issued the recommended daily allowance (RDA) for omega-3 fatty acids. However, researchers suggest that 100-200 mg daily of docosahexaenoic acid (DHA) and 200-400 mg daily of eicosapentanoic acid (EPA) were adequate for the majority of adults. 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. If fish oil supplement is preferred, then one to two capsules a day is sufficient. Each 1 g fish oil capsule normally contains 180 mg of EPA and 120 mg of DHA. Vitamin E is often contained in 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 overdosage, 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.

Precautions

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 supplements should be taken only under a physician's supervision.

Although fish oils can be helpful in relieving arthritic symptoms, patients still may need anti-inflammatory medications to adequately control the disease.

Taking any medication during pregnancy is not recommended. Women who are pregnant or breastfeeding should talk to doctors before taking fish-oil supplements or any other medications.

Because of its blood thinning activity, those who are on aspirins, nonsteroidal anti-inflammatory drugs (NSAIDS), warfarin, or other anti-clotting medications must consult a physician before using the supplements.

Side Effects

Consuming excessive amounts of fish-oil capsules can result in excessive bleeding, gastrointestinal distress, anemia, or strokes.

Interactions

Because of its blood-thinning activity, fish oil supplements may interact with aspirins, nonsteroidal anti-inflammatory drugs (NSAIDS), warfarin, or other anti-clotting medications to cause excessive bleeding.

Resources

Books

Bloomfield, Harold H. Healing Anxiety with Herbs. New York, NY: HarperCollins Publishers, Inc., 1998.

Feinstein, Alice. Prevention's Healing with Vitamins: The Most Effective Vitamin and Mineral Treatments for Everyday Health Problems and Serious Disease–From Allergies and Arthritis to Water Retention and Wrinkles. Emmaus, PA: Rodale Press, Inc., 1996.

Rudin, Donald, and Clara Felix. Omega-3 Oils: To Improve Mental health, Fight Degenerative Diseases, and Extend your Life. Garden City Park, NY: Avery Publishing Group, 1996.

White, Linda B., and Sunny Mavor. Kids, Herbs, Health: A Parents' Guide to Natural Remedies. Loveland, CO: Interweave Press, 1998.

Periodicals

"AHA Endorsement Boosts Omega-3 Usage." Food Ingredient News (April 2003).

Belluzzi, A., Stefano Boschi, Corrado Brignola, et al. "Polyunsaturated Fatty Acids and Inflammatory Bowel Disease." American Journal of Clinical Nutrition. 71 suppl (2000): 339S-42S.

Christensen, Jeppe Hagstrup, Eva Korup, Jens Aare, et al. "Fish Consumption, n-3 Fatty Acids in Cell Membranes, and Heart Rate Variability in Survivors of Myocardial Infarction with Left Ventricular Dysfunction." American Journal of Cardiolology 79 (June 15, 1997): 1670-2.

Donadio, James V. "Use of Fish Oil to Treat Patients with Immunoglobulin A Nephropathy." American Journal of Clinical Nutrition 71 suppl (2000): 373S-5S.

Harrison, Roger, and Michael Burr. "Diets Containing Oil-rich Fish Confers More Benefits than Some Pharmacological Regimens." eBMJ. 317 (1998): 1152a. http://www.bmj.com/cgi/content/full/317/7166/1152/a.

Kremer, Joel M. "n-3 Fatty Acid Supplements in Rheumatoid Arthritis." American Journal of Clinical Nutrition 71 suppl (2000): 349S-51S.

Nichols, Sonia. "Fish Oil Diets Extend Survival in Autoimmune-Prone Mice." Diabetes Week (November 26, 2001): 3.

"Omega-3 Fatty Acids in the Treatment of Depression." Harvard Mental Health Letter (October 2001).

Oommen, Tom. "Fish Oil and Cardio Protection: Herrings & Red Herrings." eBMJ 317 (1998):1152a. http://www.bmj.com/cgi/eletters/317/7166/1152.

Prichard, B.N.C., C.C.T. Smith, K.L.E. Ling, et al. "Fish Oils and Cardiovascular Disease." eBMJ 310 (April 1, 1995): 819-820. http://www.bmj.com/cgi/content/full/310/6983/819.

Simopoulos, Artemis P. "Essential Fatty Acids in Health and Chronic Disease." American Journal of Clinical Nutrition 70 suppl (1999): 560S-9S.

Willatts, P., J.S. Forsyth, M.K.D. DiModugno, et al. "Effect of Long Chain Polyunsaturated Fatty Acids in Infant Formula on Problem Solving at 10 months of Age." Lancet 352 (Aug 29, 1998): 688-691.

Organizations

American Association of Naturopathic Physicians (AANP). 601 Valley Street, Suite 105, Seattle, WA 98109. (206) 298-0125. http://www.naturopathic.org.

Other

Adam.com News. "Fish Fights Fatal Heart Attack." Adam.com. JAMA. 279 no.1 (1998): 23-28. http://www.adam.com/. (March 6, 2000).

Gassull, MA. "Dietary Lipids in Inflammatory Bowel Disease: Are They of Therapeutic Use?" Medscape. Research and Clinical Forums. 20 no.1 (1998): 197-201. http://www.medscape.com/WellsMedical/RCF/1998/v20.n01/rcf2001.23.gass/. (March 7, 2000).

Grazian, Frank. "Fish Oil Aids Psychiatric Disorders." Alternative Health News Online.http://www.altmedicine.com/. (March 7, 2000).

Graboys, Thomas B. ldquo;Angina Pectoris: Management Strategies and Guide to Interventions. Chapter 16: Dietary Recommendations." Medscape.http://www.medscape.com/PCI/angina/angina.ch16/angina.ch16_01.html. (March 7, 2000).

Moser, Marvin. "Clinical Management of Hypertension. Chapter 3: Lifestyle Modifications in the Management of Hypertension." Medscape.http://medscape.com/clinicalmanagement-hypertension.ch03.html. (March 7, 2000).

Rutz, Dan. "Researchers: Fat in the diet may affect mental ability." CNN Interactive. (September 4, 1996). http://cnn.com/HEALTH/9809/04/fat.brains/index.html

Science briefs. "Flaxseed Lowers Cholesterol." Nutrition Science News online. Nutr Res. 18 no.7 (July 1998):1203-14. http://www.nutritionscience.com. (March 6, 2000).

"The Importance of Omega-3 Fatty Acids for Adults and Children." Flax Nutrition.http://www.flaxcouncil.ca/flaxnut11.htm. (March 7, 2000).

[Article by: Teresa G. Odle]

 
Sports Science and Medicine: omega-3 fatty acids

A group of unsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA) found in some fish oils and linseed oil. They appear to change blood chemistry, reducing blood clotting and may lessen the risk of heart disease.

 
Wikipedia: omega-3 fatty acid
Types of Fats in Food
See Also

Omega-3 fatty acids are a family of polyunsaturated fatty acids which have in common a carbon-carbon double bond in the ω-3 position. (See Nomenclature for terms and discussion of ω (omega) nomenclature.)

Important nutritional essential omega-3 fatty acids are: α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). For a more complete list see List of omega-3 fatty acids. The human body cannot synthesize omega-3 fatty acids de novo, but it can form 20- and 22-carbon unsaturated omega-3 fatty acids from the eighteen-carbon omega-3 fatty acid, α-linolenic acid. These conversions occur competitively with omega-6 fatty acids, which are essential closely related chemical analogues that are derived from linoleic acid. Both the omega-3 α-linolenic acid and omega-6 linoleic acid are essential nutrients which must be obtained from food. Synthesis of the longer omega-3 fatty acids from linolenic acid within the body is competitively slowed by the omega-6 analogues. Thus accumulation of long-chain omega-3 fatty acids in tissues is more effective when they are obtained directly from food or when competing amounts of omega-6 analogs do not greatly exceed the amounts of omega-3.

Chemistry

For detail on omega (ω) nomenclature and numbering, see EFA Nomenclature.
Chemical structure of alpha-linolenic acid (ALA), an essential omega-3 fatty acid, (18:3Δ9c,12c,15c).   Although chemists count from the carbonyl carbon (blue numbering), physiologists count from the omega (ω) carbon (red numbering).  Note that from the omega end (diagram right), the first double bond appears as the third carbon-carbon bond (line segment), hence the name "omega-3"
Enlarge
Chemical structure of alpha-linolenic acid (ALA), an essential omega-3 fatty acid, (18:3Δ9c,12c,15c). Although chemists count from the carbonyl carbon (blue numbering), physiologists count from the omega (ω) carbon (red numbering). Note that from the omega end (diagram right), the first double bond appears as the third carbon-carbon bond (line segment), hence the name "omega-3"


The term omega-3 (aka "n-3", "ω-3") signifies that the first double bond exists as the third carbon-carbon bond from the terminal methyl end (ω) of the carbon chain.

Omega-3 fatty acids which are important in human nutrition are: α-linolenic acid (18:3, ALA), eicosapentaenoic acid (20:5, EPA), and docosahexaenoic acid (22:6, DHA). These three polyunsaturates have either 3, 5 or 6 double bonds in a carbon chain of 18, 20 or 22 carbon atoms, respectively. All double bonds are in the cis-configuration, i.e. the two hydrogen atoms are on the same side of the double bond.

Biological significances

The biological effects of the ω-3 fatty acids are largely mediated by their interactions with the ω-6 fatty acids; see Essential fatty acid interactions for detail.

A 1992 article by biochemist William E.M. Lands[1] provides an overview of the research into omega-3 fatty acids, and is the basis of this section. Extensive details of physiology, metabolism and nutrition are provided in his 2005 book, "Fish, Omega-3 and Human Health". A 2007 book by Evelyn Tribole, "The Ultimate Omega-3 Diet" extends this discussion with food contents and recipes by which people can balance dietary intakes of omega-3 and omega-6 fats.

The 'essential' fatty acids were given their name when researchers found that they were essential to normal growth in young children and animals. (Note that the modern definition of 'essential' is more strict.) A small amount of omega-3 in the diet (~1% of total calories) enabled normal growth, and increasing the amount had little to no additional benefit.

Likewise, researchers found that omega-6 fatty acids (such as γ-linolenic acid and arachidonic acid) play a similar role in normal growth. However, they also found that omega-6 was "better" at supporting dermal integrity, renal function, and parturition. These preliminary findings led researchers to concentrate their studies on omega-6, and it was only in recent decades that omega-3 has become of interest.

In 1963 it was discovered that the omega-6 arachidonic acid was converted by the body into pro-inflammatory agents called prostaglandins. By 1979 more of what are now known as eicosanoids were discovered: thromboxanes, prostacyclins and the leukotrienes. The eicosanoids, which have important biological functions, typically have a short active lifetime in the body, starting with synthesis from fatty acids and ending with metabolism by enzymes. However, if the rate of synthesis exceeds the rate of metabolism, the excess eicosanoids may have deleterious effects. Researchers found that omega-3 is also converted into eicosanoids, but at a much slower rate. Eicosanoids made from omega-3 fats often have opposing functions to those made from omega-6 fats (ie, anti-inflammatory rather than inflammatory). If both omega-3 and omega-6 are present, they will "compete" to be transformed, so the ratio of omega-3:omega-6 directly affects the type of eicosanoids that are produced.

This competition was recognized as important when it was found that thromboxane is a factor in the clumping of platelets, which leads to thrombosis. The leukotrienes were similarly found to be important in immune/inflammatory-system response, and therefore relevant to arthritis, lupus, and asthma. These discoveries led to greater interest in finding ways to control the synthesis of omega-6 eicosanoids. The simplest way would be by consuming more omega-3 and fewer omega-6 fatty acids.

Health benefits

On September 8, 2006, the U.S. Food and Drug Administration gave "qualified health claim" status to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) omega-3 fatty acids, stating that "supportive but not conclusive research shows that consumption of EPA and DHA omega-3 fatty acids may reduce the risk of coronary heart disease."[2] This updated and modified their health risk advice letter of 2001 (see below).

People with certain circulatory problems, such as varicose veins, benefit from fish oil. Fish oil stimulates blood circulation and increases the breakdown of fibrin, a compound involved in clot and scar formation.

A 2006 report in the Journal of the American Medical Association concluded that their review of literature covering cohorts from many countries with a wide variety of demographic characteristics failed to demonstrate a link between omega-3 fatty acids and cancer prevention.[3] This is similar to the findings of a review by the British Medical Journal of studies up to February 2002 that failed to find clear effects of long and shorter chain omega-3 fats on total mortality, combined cardiovascular events and cancer.[4]

In April 2006, a team led by Lee Hooper at the University of East Anglia in Norwich, UK, published a review of almost 100 separate studies into omega-3 fatty acids, found in abundance in oily fish. It concluded that they do not have a significant protective effect against cardiovascular disease.[5] This meta-analysis was controversial and stands in stark contrast with two different reviews also performed in 2006 by the American Journal of Clinical Nutrition[6] and a second JAMA review[7] that both indicated decreases in total mortality and cardiovascular incidents (i.e. myocardial infarctions) associated with the regular consumption of fish and fish oil supplements. In addition Omega-3 has shown to aid in other mental disorders such as aggression and ADHD (Attention Deficit Hyperactive Disorder).

Several studies published in 2007 have been more positive. In the March 2007 edition of the journal Atherosclerosis, 81 Japanese men with unhealthy blood sugar levels were randomly assigned to receive 1800 mg daily of eicosapentaenoic acid (EPA - an omega-3 essential fatty acid from fish oil) with the other half being a control group. The thickness of the carotid arteries and certain measures of blood flow were measured before and after supplementation. This went on for approximately two years. A total of 60 patients (30 in the EPA group and 30 in the control group) completed the study. Those given the EPA had a statistically significant decrease in the thickness of the carotid arteries along with improvement in blood flow. The authors indicated that this was the first demonstration that administration of purified EPA improves the thickness of carotid arteries along with improving blood flow in patients with unhealthy blood sugar levels.[citation needed]

In another study published in the American Journal of Health System Pharmacy March 2007, patients with high triglycerides and poor coronary artery health were given 4 grams a day of a combination of EPA and DHA along with some monounsaturated fatty acids. Those patients with very unhealthy triglyceride levels (above 500 mg/dl) reduced their triglycerides on average 45% and their VLDL cholesterol by more than 50%. VLDL is a bad type of cholesterol and elevated triglycerides can also be deleterious for cardiovascular health.[citation needed]

There was another study published on the benefits of EPA in the prestigious journal The Lancet in March 2007. This study involved over 18,000 patients with unhealthy cholesterol levels. The patients were randomly assigned to receive either 1,800 mg a day of EPA with a statin drug or a statin drug alone. The trial went on for a total of five years. It was found at the end of the study those patients in the EPA group had superior cardiovascular function. Non-fatal coronary events were also significantly reduced in the EPA group. The authors concluded that EPA is a promising supplement for promoting cardiovascular health.[citation needed]

Another study regarding fish oil was published in the journal Nutrition in April 2007. Sixty four healthy Danish infants received either cow's milk or infant formula alone or with fish oil from nine to twelve months of age. It was found that those infants supplemented with fish oil had improvement in immune function maturation with no apparent reduction in immune activation.[citation needed]

There was yet another study on omega-3 fatty acids published in the April 2007 Journal of NeuroScience. A group of mice were genetically modified to develop accumulation of amyloid and tau proteins in the brain similar to that seen in people with poor memory. The mice were divided into four groups with one group receiving a typical American diet (with high ratio of omega-6 to omega-3 fatty acids being 10 to 1). The other three groups were given food with a balanced 1 to 1 omega 6 to omega 3 ratio and two additional groups supplemented with DHA plus long chain omega-6 fatty acids. After three months of feeding, all the DHA supplemented groups were noted to have a lower accumulation of beta amyloid and tau protein. It is felt that these abnormal proteins may contribute to the development of memory loss in later years.[citation needed]

Finally, there was a study published regarding omega-3 supplementation in children with learning and behavioral problems. This study was published in the April 2007 edition of the Journal of the Developmental and Behavioral Pediatrics (5), where 132 children, between the ages of seven to twelve years old, with poor learning, participated in a randomized, placebo-controlled, double-blinded interventional trial. A total of 104 children completed the trial. For the first fifteen weeks of this study, the children were given polyunsaturated fatty acids (omega-3 and omega-6, 3000 mg a day), polyunsaturated fatty acids plus multi-vitamins and minerals or placebo. After fifteen weeks, all groups crossed over to the polyunsaturated fatty acids (PUFA) plus vitamins and mineral supplement. Parents were asked to rate their children's condition after fifteen and thirty weeks. After thirty weeks, parental ratings of behavior improved significantly in nine out of fourteen scales. The lead author of the study, Dr. Sinn, indicated the present study is the largest PUFA trial to date with children falling in the poor learning and focus range. The results support those of other studies that have found improvement in poor developmental health with essential fatty acid supplementation.[8]

Research in 2005-06 has suggested that the in-vitro anti-inflammatory activity of omega-3 acids translates into clinical benefits. Cohorts of neck pain patients and of rheumatoid arthritis sufferers have demonstrated benefits comparable to those receiving standard NSAIDs [citation needed]. Those who follow a Mediterranean-style diet tend to have less heart disease, higher HDL ("good") cholesterol levels [9] and higher proportions of omega-3 in tissue highly unsaturated fatty acids [10]. Similar to those who follow a Mediterranean diet, Arctic-dwelling Inuit - who consume high amounts of omega-3 fatty acids from fatty fish - also tend to have higher proportions of omega-3, increased HDL cholesterol and decreased triglycerides (fatty material that circulates in the blood) and less heart disease. Eating walnuts (the ratio of omega 3 to omega 6 is circa 1:4 respectively [11] [12] ) (which have several-fold more omega-3 ALA than omega-6 LA[citation needed]) was reported to lower total cholesterol by 4% relative to controls when people also ate 27% less cholesterol.[13]

Health risks

In a letter dated October 31, 2000 entitled Letter Regarding Dietary Supplement Health Claim for omega-3 Fatty Acids and Coronary Heart Disease, the United States Food and Drug Administration Center for Food Safety and Applied Nutrition, Office of Nutritional Products, Labeling, and Dietary Supplements noted that the known or suspected risks of EPA and DHA omega-3 fatty acids may include:

  • There have been reports that increased bleeding can occur if overused (normally over 3 grams per day) by a patient who is also taking aspirin or coumadin (warfarin). However, this is disputed.[1]
  • The possibility of hemorrhagic stroke.
  • Oxidation of omega-3 fatty acids forming biologically active oxidation products.
  • Reduced glycemic control among diabetics.
  • Suppression of immune and inflammation responses, and consequently, decreased resistance to infections and increased susceptibility to opportunistic bacteria.
  • An increase in concentration of LDL cholesterol in some individuals.

Subsequent advices from the FDA and national counterparts have permitted health claims associated with heart health.

Warning for persons with Congestive Heart Failure (CHF)

Persons with congestive heart failure, chronic recurrent angina or evidence that their heart is receiving insufficient blood flow are advised to talk to their doctor before taking omega-3 fatty acids. It may be prudent for such persons to avoid taking omega-3 fatty acids or eating foods that contain them in substantial amounts.[14]

In congestive heart failure, cells that are only barely receiving enough blood flow become electrically hyperexcitable. This, in turn, can lead to increased risk of irregular heartbeats, which, in turn, can cause sudden cardiac death. Omega-3 fatty acids seem to stabilize the rhythm of the heart by effectively preventing these hyperexcitable cells from functioning by increasing the blood flow, thereby reducing the likelihood of irregular heartbeats and sudden cardiac death. For most people, this is obviously beneficial and would account for most of the large reduction in the likelihood of sudden cardiac death.

Research frontiers

Autism

According to an Internet survey, approximately 30% of parents use omega-3 supplements as a therapy for children with autism.[15] There are currently only a few studies on the effectiveness of essential fatty acid supplementation as a treatment of autism and none of these has been well-controlled.[16][17][18][19] Bell and colleagues reported that parents of 18 children with autism who had been supplemented with fish oil for six months described improvements in overall health, cognition, sleep patterns, social interaction, and eye contact.[20] Another case report found that a child with autism given 540 mg of EPA per day over a four week period experienced a complete elimination of his previous anxiety about everyday events as reported by his parents and clinician.[21]

Low birth weight

In a study of nearly 9,000 pregnant women, researchers found women who ate fish once a week during their first trimester had 3.6 times less risk of low birth weight and premature birth than those who ate no fish. Low consumption of fish was a strong risk factor for preterm delivery and low birth weight.[22] However, attempts by other groups to reverse this increased risk by encouraging increased pre-natal consumption of fish were unsuccessful.[23]

Psychological disorders

Omega-3s are known to have membrane-enhancing capabilities in brain cells.[5] One medical explanation is that omega-3s play a role in the fortification of the myelin sheaths. Not coincidentally, omega-3 fatty acids comprise approximately eight percent of the average human brain according to Dr. David Horrobin, a pioneer in fatty acid research. Ralph Holman of the University of Minnesota, another major researcher in studying essential fatty acids, who gave it the name, surmised how omega-3 components are analogous to the human brain by stating that "DHA is structure, EPA is function."

A benefit of omega-3s is helping the brain to repair damage by promoting neuronal growth.[5] In a six-month study involving people with schizophrenia and Huntington's disease who were treated with EPA or a placebo, the placebo group had clearly lost cerebral tissue, while the patients given the supplements had a significant increase of grey and white matter.[24]

In the prefrontal cortex (PFC) of the brain, low brain omega-3s are thought to lower the dopaminergic neurotransmission in this brain area, possibly contributing to the negative and neurocognitive symptoms in schizophrenia. This reduction in dopamine system function in the PFC may lead to an overactivity in dopaminergic function in the limbic system of the brain which is suppressively controlled by the PFC dopamine system, causing the positive symptoms of schizophrenia (Ohara, 2007). This mechanism may explain why omega-3 supplementation shows effects against both positive, negative and neurocognitive symptoms in schizophrenia.

Consequently, the past decade of omega-3 fatty acid research has procured some Western interest in omega-3s as being a legitimate 'brain food.' Still, recent claims that one's intelligence quotient, psychological tests measuring certain cognitive skills, including numerical and verbal reasoning skills, are increased on account of omega-3s consumed by pregnant mothers remain unreliable and controversial. An even more significant focus of research, however, lies in the role of omega-3s as a non-prescription treatment for certain psychiatric and mental diagnoses and has become a topic of much research and speculation.

In 1998, Andrew L. Stoll, MD and his colleagues at Harvard University conducted a small double-blind placebo-controlled study in thirty patients diagnosed with bipolar disorder. Over the course of nine months, he gave 15 subjects capsules containing olive oil, and another 15 subjects capsules containing nine grams of pharmaceutical-quality EPA and DHA. In doing so, he was able to make the general distinction between the placebo group failing to improve while the Omega-3 group experienced a noticeable degree of recovery. Though Stoll believes that the 1999 experiment was not as optimal as it could have been and has accordingly pursued further research, the foundation has been laid for more researchers to explore the theoretical association between absorbed omega-3s and signal transduction inhibition in the brain.[25]

"Several epidemiological studies suggest covariation between seafood consumption and rates of mood disorders. Biological marker studies indicate deficits in omega-3 fatty acids in people with depressive disorders, while several treatment studies indicate therapeutic benefits from omega-3 supplementation. A similar contribution of omega-3 fatty acids to coronary artery disease may explain the well-described links between coronary artery disease and depression. Deficits in omega-3 fatty acids have been identified as a contributing factor to mood disorders and offer a potential rational treatment approach." (American Journal of Psychiatry 163:1098-1100, June 2006)

In 2006, a review of published trials in the American Journal of Clinical Nutrition found that "the evidence available provides little support" for the use of fish or the n–3 long-chain polyunsaturated fatty acids contained in them to improve depressed mood. The study used results of twelve randomized controlled trials in its meta-analysis. The review recommended that "larger trials with adequate power to detect clinically important benefits" be performed. [26]

Short bowel syndrome

Case reports show that an omega-3 rich emulsion, Omegaven, reduced the risk of liver damage in this condition.

Dietary sources

Daily values

As macronutrients, fats are not assigned recommended daily allowances. Macronutrients have AI (Acceptable Intake) and AMDR (Acceptable Macronutrient Distribution Range) instead of RDAs. The AI for n-3 is 1.6 grams/day for men and 1.1 grams/day for women[27] while the AMDR is 0.6% to 1.2% of total energy.[28]

"A growing body of literature suggests that higher intakes of α-linolenic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) may afford some degree of protection against coronary heart disease. Because the physiological potency of EPA and DHA is much greater than that for α-linolenic acid, it is not possible to estimate one AMDR for all n-3 fatty acids. Approximately 10 percent of the AMDR can be consumed as EPA and/or DHA."[28]

There was insufficient evidence as of 2005 to set a UL (upper tolerable limit) for n-3 fatty acids.[27]

Researchers believe the ideal omega-6 intake should be no more than 4-5 times that of our omega-3 intake. The National Institutes of Health recently published recommended daily intakes of fatty acids, specific recommendations include 650 mg of EPA and DHA, 2.22 g/day of alpha-linolenic acid and 4.44 g/day of linoleic acid. [citation needed]

A perceived risk of fish oil omega-3 supplementation has been heavy metal poisoning by the body's accumulation of traces of heavy metals, in particular mercury, lead, nickel, arsenic and cadmium as well as other contaminants (PCBs, furans, dioxins), which potentially might be found especially in less-refined fish oil supplements.[citation needed]. The fish oil industry has successfully improved the quality of fish oils on the market. An independent test in 2006 of 42 fish oils on the US market by www.consumerlab.com found that all of the products exceeded safety standards for potential contaminants.[29] The FDA recommends that total dietary intake of omega-3 fatty acids from fish not exceed 3 grams per day, of which no more than 2 grams per day are from nutritional supplements.[2]

Historically, the Council for Responsible Nutrition (CRN) and the World Health Organization (WHO) have published acceptable standards regarding contaminants in fish oil. The most stringent current standard is the International Fish Oils Standard (IFOS). Fish oils that typically make this highest grade are those that are molecularly distilled under vacuum, and have virtually no measurable level of contaminants (measured parts per billion and parts per trillion).

Omega supplementation in food has been a significant recent trend in food fortification, with global food companies launching omega-3 fortified bread, pizza, yogurt, orange juice, children's pasta, milk, confections and infant formula.

Fish

Early humans ate inter-tidal shellfish, while living a shoreline existence in Africa.[30] Now, as then, inter-tidal herbivorous shellfish such as mussels and clams can help people reach a healthy balance of omega-3 and omega-6 fats in their diets.[30][31]

The most widely available source of EPA and DHA is cold water oily fish such as wild salmon, herring, mackerel, anchovies and sardines. Oils from these fish have a profile of around seven times as much omega-3 as omega-6. Farmed salmon, being grain fed, have a higher proportion of omega-6 than wild salmon. Other oily fish such as tuna also contain omega-3 in somewhat lesser amounts. Consumers of oily fish should be aware of the potential presence of heavy metals and fat-soluble pollutants like PCBs and dioxins which may