Overview:

Omega-6 fatty acids are considered essential fatty acids (EFAs). They are essential to human health but cannot be made in the body. For this reason, they must be obtained from food. Omega-3 fatty acids are another important group of essential fatty acids. Together, omega-3 and omega-6 fatty acids play a crucial role in brain function as well as normal growth and development. EFAs belong to the class of fatty acids called polyunsaturated fatty acids (PUFAs). They are generally necessary for stimulating skin and hair growth, maintaining bone health, regulating metabolism, and maintaining reproductive capability.

Deficiencies in EFAs can lead to reduced growth, a scaly rash called dermatitis, infertility, and lack of ability to fight infection and heal wounds. Lack of omega-6 fatty acids, however, is extremely rare in diets of those living in certain Western countries, particularly the United States and Israel. In fact, North American and Israeli diets tend to have too much omega-6, particularly in relation to omega-3 fatty acids. This imbalance contributes to long-term diseases, such as heart disease, cancer, asthma, arthritis, and depression. A healthy diet should consist of roughly 2 - 4 times more omega-6 fatty acids than omega-3 fatty acids. The typical American diet tends to contain 14 - 25 times more omega-6 fatty acids than omega-3 fatty acids, and many researchers believe this imbalance is a significant factor in the rising rate of inflammatory disorders in the United States.

In contrast, a Mediterranean diet is made up of a healthier and more appropriate balance between omega-3 and omega-6 fatty acids. The Mediterranean diet includes a generous amount of whole grains, fresh fruits and vegetables, fish, olive oil, and garlic; plus, there is little meat, which is high in omega-6 fatty acids.

There are several different types of omega-6 fatty acids. Most omega-6 fatty acids are consumed in the diet from vegetable oils as linoleic acid (LA). Be careful not to confuse this with alpha-linolenic acid [ALA] which is an omega-3 fatty acid. Linoleic acid is converted to gamma-linolenic acid (GLA) in the body and then further broken down to arachidonic acid (AA). AA can also be consumed directly from meat, and GLA can be ingested from several plant-based oils including evening primrose oil (EPO), borage oil, and black currant seed oil.

Eicosanoids formed from arachidonic acid (AA, the omega-6 family) have the potential to increase blood pressure, inflammation, platelet aggregation, thrombosis, vasospasm, allergic reactions, and cell proliferation (growth). Those formed from eicosapentanoic acid (EPA, the omega-3 family) have opposing affects. Omega-6 and omega-3 fatty acids are not interchangeable, and humans must consume both.

In contrast, gamma-linolenic acid (GLA, the omega-6 family) may actually reduce inflammation. Much of the GLA taken as a supplement is not converted to AA, but rather to a substance called dihomogamma-linolenic acid (DGLA). DGLA competes with AA and prevents the negative inflammatory effects that AA would otherwise cause in the body. In addition, DGLA becomes part of a particular series of substances, called prostaglandins, that can reduce inflammation. Having adequate amounts of certain nutrients in the body (including magnesium, zinc, and vitamins C, B3, and B6) helps promote the conversion of GLA to DGLA rather than to AA that increase inflammation.

It may be more important to supplement the diet with omega-3 fatty acids to reduce inflammation and prevent heart disease than omega-6 fatty acids, as most individuals are not omega-6 deficient.

Uses:

Some clinicians and preliminary clinical research suggests that omega-6 fatty acids may be useful for the following health conditions:

Acne and psoriasis

Early clinical research has reported that dietary linoleic acid (LA, from corn oil and others) may prove beneficial for these skin conditions by replenishing the low levels of LA in these lesions. Further clinical research is needed in this area.

Alcoholism

EPO may help lessen cravings for alcohol and prevent liver damage. Most of this information comes from animal studies, and more research in humans is needed.

Allergies

People who are prone to allergies may require more essential fatty acids (EFAs) and often have difficulty converting LA to GLA. In fact, women and infants who are prone to allergies appear to have lower levels of GLA in breast milk and blood.

The use of EFAs to prevent allergic reactions or reduce their magnitude has had mixed results in clinical studies. There have been some reports of individuals lessening their allergic reaction by taking GLA from EPO. Well-conducted research studies are needed to determine whether EPO can be helpful for large numbers of people with allergies.

A clinical study evaluating the dietary intake of omega-6 fatty acids relative to the risk of having hay fever (or allergic rhinitis) found an increase risk of developing symptoms associated with hay fever (including runny nose, and itchy, watery eyes) when using omega-6 fatty acids.

Omega-6 fatty acids from the diet or supplements, such as GLA from EPO or other sources, have a longstanding history of folk use for allergies. Whether this supplement improves symptoms of the conditions listed above may be very individual. Work with your health care provider to first determine if it is safe for you to try GLA and then follow your allergy symptoms closely for any signs of improvement or lack or improvement.

Anorexia nervosa

Clinical studies suggest that women, and possibly men, with anorexia nervosa have lower than optimal levels of polyunsaturated fatty acids (PUFAs, including omega-6 fatty acids) and display abnormalities in the use of these fatty acids in the body. To prevent the metabolic complications associated with essential fatty acid deficiencies, some recommend that treatment programs for anorexia nervosa include PUFA-rich foods, such as organ meats and fish.

Attention deficit/hyperactivity disorder (ADHD)

Clinical studies suggest that children with ADHD have lower levels of EFAs, both omega-6s and omega-3s. EFAs are important to normal brain and behavioral function. Because of their effects on the brain and nervous system and the low levels of EFAs measured in those with ADHD, scientists have speculated that replacement of EFAs through food or supplements may help lessen the behaviors and symptoms of this condition.

Clinical research to date has suggested an improvement in symptoms and behaviors related to ADHD from omega-3 fatty acids. Results of clinical studies supplying omega-6 fatty acids in the form of gamma-linolenic acid (GLA) to children with ADHD, however, have been mixed and, therefore, not conclusive. More research on GLA for ADHD is needed before conclusions can be drawn. In the meantime, ensuring a healthier balance of omega-3 to omega-6 fatty acids in the diet seems worthwhile for those with this condition.

Cancer

Results of studies looking at the relationship of omega-6 fatty acids to cancer have been mixed. While LA and AA are cancer promoting in studies of colon, breast, and other cancers, GLA and EPO have shown some benefit for breast cancer in certain studies. The information is not conclusive and is somewhat controversial. It may be important to eat a diet with the proper balance of omega-3 to omega-6 fatty acids (see How To Take It), starting from a young age, to try to prevent the development of cancer.

Diabetes

Omega-6 fatty acid supplementation, in the form of GLA from evening primrose oil (EPO) or other sources, may assist nerve function and help prevent nerve disease experienced by those with diabetes (called peripheral neuropathy and felt as numbness, tingling, pain, burning, or lack of sensation in the feet or legs).

Eczema

Several clinical studies suggest that EPO is more beneficial than placebo at relieving symptoms associated with this skin condition such as itching, redness, and scaling. However, other clinical studies have not had the same positive results testing GLA derived from EPO. Talk to your health care provider about the possibility and safety of trying EPO for this eczema.

Eye disease

GLA may be beneficial in dry-eye conditions such as Sjögren's syndrome (a condition with symptoms of dry eyes, dry mouth, and, often, arthritis).

Heart disease and high blood pressure

Animal studies suggest that GLA may lower the blood pressure of hypertensive rats -- either alone or in combination with two important omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), both found in fish and fish oil. Together with EPA and DHA, the GLA helped to prevent the development of heart disease in these animals as well. It is unclear whether these benefits would occur in people.

Peripheral artery disease causes blockages in the blood vessels in the legs from atherosclerosis (hardening of the arteries), causing cramping pain with walking. In one clinical study evaluating individuals with peripheral artery disease, men and women with this condition did experience improvement in their blood pressure from the combination of EPA and GLA. Much more research is needed in people before conclusions can be drawn.

Menopausal symptoms

Although EPO has gained some popularity for treating hot flashes during menopause, the research to date has not demonstrated a benefit of GLA or EPO over taking a placebo. However, there are women who report improvement in symptoms while taking EPO. Talk to your health care professional about whether it is safe for you to try EPO or another form of GLA supplements to alleviate hot flashes.

Multiple Sclerosis

Evening primrose oil (EPO) has a long history of use in treating multiple sclerosis (MS) although some of the clinical research on its effectiveness has been conflicting. MS patients seeking to incorporate the use of EPO in their treatment regimens should consult with a health care provider.

Osteoporosis

A deficiency in essential fatty acids, including GLA and eicosapentaenoic acid (EPA (an omega-3 fatty acid), can lead to severe bone loss and osteoporosis. Clinical studies have reported that supplements of GLA and EPA help maintain or increase bone mass. Essential fatty acids may also enhance calcium absorption, increase calcium deposits in bones, diminish calcium loss in urine, improve bone strength, and enhance bone growth, all of which may contribute to improved bone mass and, therefore, strength.

Premenstrual syndrome (PMS)

Although results of studies have been mixed, some women find relief of their PMS symptoms when using GLA supplements from EPO or another source. The symptoms that seem to be helped the most are breast tenderness and feelings of depression as well as irritability and swelling and bloating from fluid retention. Breast tenderness from causes other than PMS may also improve with use of GLA.

Rheumatoid arthritis

Some preliminary clinical studies suggest that GLA from EPO, borage oil, or black currant seed oil may diminish joint pain, swelling, and morning stiffness. GLA may also allow for reduction in amount of pain medication used by those with rheumatoid arthritis. The clinical studies to date, however, have been small in size. Additional research in this area is needed. When using GLA for symptoms of arthritis, it may take 1 - 3 months for benefits to appear.

Tuberculosis

Animal studies suggest that guinea pigs fed a diet rich in omega-6 fatty acids were better able to fight this infection than guinea pigs fed a diet rich in omega-3 fatty acids. Whether this would help people with tuberculosis is not known.

Ulcers

Preliminary evidence from test tube and animal studies suggest that GLA from EPO may have anti-ulcer properties. It is premature to know how this might apply to people with stomach or intestinal ulcers or gastritis (inflammation of the stomach).

Weight loss

Results of clinical studies regarding use of EPO for weight loss have been mixed and, therefore, use of this type of supplement may not work for everyone. One clinical study suggests that if the supplement is going to work, it does so mainly for overweight individuals for whom obesity runs in the family. In addition, a few other small clinical studies suggest that the more overweight you are, the more likely that EPO will help. In fact, if your body weight is only 10% above normal (for example, 10 - 20 pounds above average), EPO is unlikely to help you lose weight.

Dietary Sources:

The American diet provides more than 10 times the needed amount of omega-6 oils in the form of linoleic acid (LA). This is because it comprises the primary oil ingredient added to most processed foods and is found in commonly used cooking oils, including sunflower, safflower, corn, cottonseed, and soybean oils.

Omega-6 fatty acids in the form of gamma linolenic acid (GLA) and LA are found in the plant seed oils of evening primrose, black currant, borage, and fungal oils.

Arachidonic acid (AA) of the omega-6 series is found in egg yolk, meats in general, particularly organ meats, and other animal-based foods.

Available Forms:

Omega-6 fatty acids are commercially available in supplemental oils that contain linoleic acid (LA) and gamma linolenic acid (GLA), such as evening primrose (Oenothera biennis) and black currant (Ribes nigrum ) oils. Spirulina (often called blue-green algae) also contains GLA.

How to Take It:

For general health, there should be a balance between omega-6 and omega-3 fatty acids. The ratio should be in the range of 2:1 - 4:1, omega-6 to omega-3. The average diet provides sufficient omega-6 fatty acids, so supplementation is usually not necessary unless treating for a specific condition such as eczema or psoriasis, arthritis, diabetes, or breast tenderness (mastalgia).

Pediatric

For nursing infants: Adequate amounts of essential fatty acids are generally supplied in breast milk if the mother is adequately nourished.

For eczema in children 2 - 18 years of age: Evening primrose oil (EPO), 3 grams daily, divided into several smaller doses throughout the day. It is reported that the maximum dose should not be greater than 0.5 gram per kilogram of body weight daily. Consult a health care provider before using supplements in children.

Adult

For eczema or atopic dermatitis: Evening primrose oil (EPO), 4,000 - 8,000 mg daily, or gamma-linolenic acid (GLA), 2,800 mg daily, both divided into several smaller doses throughout the day.

For rheumatoid arthritis: Evening primrose oil (EPO), 3,000 mg daily, or gamma-linolenic acid (GLA), 1,400 mg daily, both divided into several smaller doses throughout the day.

For diabetes: Gamma-linolenic acid (GLA), 480 mg daily, divided into several smaller doses throughout the day.

For breast tenderness (mastalgia) or PMS: Evening primrose oil (EPO), 3,000 - 4,000 mg daily, divided into several smaller doses throughout the day.

Precautions:

Because of the potential for side effects and interactions with medications, dietary supplements should be taken only under the supervision of a knowledgeable health care provider.

Omega-6 should not be used if you have a seizure disorder because there have been reports of these supplements inducing seizures. Several reports describe seizures in individuals taking evening primrose oil (EPO). Some of these seizures developed in people with a previous seizure disorder, or in individuals taking EPO in combination with anesthetics. Based on these reports, people with seizure disorders should not take EPO. Patients who plan to undergo surgery requiring anesthesia should stop taking EPO 2 weeks ahead of time because of the possibility of seizure.

Borage seed oil, and possibly other sources of gamma-linolenic acid (GLA), should not be used during pregnancy because they may be harmful to the fetus and induce early labor.

Doses of GLA greater than 3,000 mg per day should be avoided because, at that point, production of arachidonic acid (AA) increases, which may cause and increase in inflammation.

Side effects of EPO can include occasional headache, abdominal pain, nausea, and loose stools. In animal studies, gamma-linolenic acid (an ingredient of evening primrose oil) is reported to decrease blood pressure. Early results in human studies do not show consistent changes in blood pressure.

Laboratory studies found that omega-6 fatty acids, such as the fat found in corn oil, promote the growth of prostate tumor cells. Until further research is performed in this area, health care professionals recommend not using omega-6 fatty acids, including GLA, if risk or symptoms of prostate cancer exist.

Possible Interactions:

If you are currently being treated with any of the following medications, you should not use omega-6 supplements without first talking to your health care provider.

Blood thinning medications -- Individuals taking blood thinning medications, including warfarin (Coumadin) or clopidogrel (Plavix) should not take omega-6 fatty acid supplements without consulting a health care provider. Omega-6 and omega-3 fatty acids may increase the risk of bleeding in sensitive individuals.

Ceftazidime -- Gamma linolenic acid (GLA) may increase the effectiveness of ceftazidime (an antibiotic in a class known as cephalosporins), against a variety of bacterial infections.

Chemotherapy for cancer -- GLA may increase the effects of anti-cancer treatments, such as doxorubicin, cisplatin, carboplatin, idarubicin, mitoxantrone, tamoxifen, vincristine, and vinblastine.

Cyclosporine -- Taking omega-6 fatty acids during therapy with cyclosporine, a medication used to suppress the immune system after an organ transplant, for example, may increase the immunosuppressive effects of this medication and may protect against kidney damage (a potential side effect from this medication).

Phenothiazines -- Individuals taking a class of medications called phenothiazines, including chlorpromazine (Thorazine), fluphenazine (Stelazine), perphenazine (Trilafon), promethazine (Compazine), and thioridazine (Mellaril) to treat schizophrenia should not take evening primrose oil (EPO) because it may interact with these medications and increase the risk of seizures. The same may be true for other omega-6 containing supplements.

Alternative Names:

Evening primrose oil; EPO; Linoleic acid; LA