Omega-6 fatty acids are considered essential fatty acids: They are necessary for human health but the body can' t make them -- you have to get them through food. Along with omega-3 fatty acids, omega-6 fatty acids play a crucial role in brain function, as well as normal growth and development. Also known as polyunsaturated fatty acids (PUFAs), they help stimulate skin and hair growth, maintain bone health, regulate metabolism, and maintain the reproductive system.
A healthy diet contains a balance of omega-3 and omega-6 fatty acids. Omega-3 fatty acids help reduce inflammation, and some omega-6 fatty acids tend to promote inflammation. In fact, some studies suggest that elevated intakes of omega-6 fatty acids may play a role in Complex Regional Pain Syndrome. The typical American diet tends to contain 14 - 25 times more omega-6 fatty acids than omega-3 fatty acids.
The Mediterranean diet, on the other hand, has a healthier balance between omega-3 and omega-6 fatty acids. Many studies have shown that people who follow this diet are less likely to develop heart disease. The Mediterranean diet does not include much meat (which is high in omega-6 fatty acids, though grass fed beef has a more favorable omega-3 to omega-6 fatty acid ratio) and emphasizes foods rich in omega-3 fatty acids, including whole grains, fresh fruits and vegetables, fish, olive oil, garlic, as well as moderate wine consumption.
There are several different types of omega-6 fatty acids, and not all promote inflammation. Most omega-6 fatty acids in the diet come from vegetable oils, such as linoleic acid (LA). Be careful not to confuse this with alpha-linolenic acid (ALA), an omega-3 fatty acid. Linoleic acid is converted to gamma-linolenic acid (GLA) in the body. It is then further broken down to arachidonic acid (AA). GLA is found in several plant based oils, including evening primrose oil (EPO), borage oil, and black currant seed oil.
GLA may actually reduce inflammation. Much of the GLA taken as a supplement is converted to a substance called DGLA that fights inflammation. Having enough of certain nutrients in the body (including magnesium, zinc, and vitamins C, B3, and B6) helps promote the conversion of GLA to DGLA.
Omega-6 fatty acids may be useful for the following health conditions:
Some studies show that taking gamma linolenic acid (GLA) for 6 months or more may reduce symptoms of nerve pain in people with diabetic neuropathy. People who have good blood sugar control may find GLA more effective than those with poor blood sugar control.
Studies are mixed as to whether evening primrose oil helps reduce symptoms of rheumatoid arthritis. Some preliminary evidence suggests evening primrose oil may reduce pain, swelling, and morning stiffness; but other studies have found no effect. When using GLA for symptoms of arthritis, it may take 1 - 3 months for benefits to appear. It is unlikely that evening primrose oil would help stop progression of the disease, so joint damage would still occur.
Omega-6 fatty acids from food or supplements, such as GLA from evening primrose oil or other sources, have a longstanding history of folk use for allergies. Women who are prone to allergies appear to have lower levels of GLA in breast milk and blood. However, there is no good scientific evidence that taking GLA helps reduce allergy symptoms. Well conducted research studies are needed.
If you decide to try GLA for allergies, work with your health care provider to first determine if it is safe for you. Then follow your allergy symptoms closely for any signs of improvement or lack or improvement.
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. Some studies indicate that taking fish oil (containing omega-3 fatty acids) may help reduce ADHD symptoms, though the studies have not been well designed. Studies that used evening primrose oil have found it was no better than placebo at reducing symptoms.
One study found that women with breast cancer who took GLA had a better response to tamoxifen (a drug used to treat estrogen sensitive breast cancer) than those who took only tamoxifen. Other studies suggest that GLA inhibits tumor activity among breast cancer cell lines. There is some research suggesting that a diet rich in omega-6 fatty acids may promote breast cancer development.
Evidence is mixed as to whether evening primrose oil can help reduce symptoms of eczema. Some early studies found benefit, but they were not well designed. Later studies that examined people who took evening primrose oil for 16 - 24 weeks found no improvement in symptoms. If you want to try evening primrose oil, talk to your health care provider about whether it is safe for you.
High blood pressure (Hypertension)
There is some preliminary evidence that GLA may help reduce high blood pressure, either alone or in combination with omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), found in fish oil. In one study, men with borderline high blood pressure who took 6g of blackcurrant oil had a reduction in diastolic blood pressure compared to those who took placebo.
Another study examined people with intermittent claudication, pain in the legs while walking that is caused by blockages in the blood vessels. Those who took GLA combined with EPA had a reduction in systolic blood pressure compared to those who took placebo.
More research is needed to see whether GLA is truly effective for hypertension.
Evening primrose oil has gained popularity as a way to treat hot flashes associated with menopause, but so far studies have not shown that it works. If you want to try evening primrose oil for hot flashes and night sweats, ask your health care provider whether it is safe and right for you.
Some evidence suggests that evening primrose oil may reduce breast pain and tenderness in people with cyclic mastalgia. It may also help reduce symptoms to a lesser extent in people with non cyclic mastalgia. However, it does not seem to be effective for severe breast pain.
Evening primrose oil has been suggested as an additional treatment (in addition to standard therapy) for multiple sclerosis (MS) although there is no scientific evidence that it works. MS patients who want to add evening primrose oil to their treatment regimens should talk with a health care provider.
Some studies suggest that people who don' t get enough of some essential fatty acids (particularly EPA and GLA) are more likely to have bone loss than those with normal levels of these fatty acids. In a study of women over 65 with osteoporosis, those who took EPA and GLA supplements had less bone loss over 3 years than those who took placebo. Many of these women also experienced an increase in bone density.
Premenstrual syndrome (PMS)
Although most studies have found no effect, some women report relief of PMS symptoms when using GLA. 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.
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 -- and some health educators advocate even lower ratios. The average diet provides plenty of omega-6 fatty acids, so supplements are usually not necessary. People with specific conditions such as eczema or psoriasis, arthritis, diabetes, or breast tenderness (mastalgia) may want to ask their health care providers about taking omega-6 supplements.
Omega-6 fatty acids are 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.
The average diet provides sufficient omega-6 fatty acids, so supplementation is usually not necessary unless you're treating a specific condition, such as eczema or psoriasis, arthritis, diabetes, or breast tenderness (mastalgia).
The dose and form of omega-6 fatty acids to be supplemented depends on many factors, including condition being treated, age, weight, and other medications and supplements being used. Speak to your doctor to determine what form and what dose of omega-6 fatty acids are most appropriate for you.
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.
Do not take omega-6 if you have a seizure disorder because there have been reports of these supplements causing seizures. Several reports describe seizures in people taking evening primrose oil. Some of these seizures developed in people with a previous seizure disorder, or in people taking evening primrose oil in combination with anesthetics. People who plan to undergo surgery requiring anesthesia should stop taking evening primrose oil 2 weeks ahead of time.
Borage seed oil, and possibly other sources of gamma-linolenic acid (GLA), should not be taken during pregnancy because they may harm the fetus and induce early labor.
Avoid doses of GLA greater than 3,000 mg per day. At that level, an increase in inflammation may occur.
Side effects of evening primrose oil can include occasional headache, abdominal pain, nausea, and loose stools. In animal studies, GLA is reported to decrease blood pressure. Early results in human studies do not show consistent changes in blood pressure.
Laboratory studies suggest that omega-6 fatty acids, such as the fat found in corn oil, promote the growth of prostate tumor cells. Until more research is done, health care professionals recommend not taking omega-6 fatty acids, including GLA, if you are at risk of or have prostate cancer.
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 -- People 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.
Ceftazidime -- Gamma linolenic acid (GLA) may increase the effectiveness of ceftazidime. Ceftazidinme, an antibiotic, is used 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 -- Cyclosporine is a medication used to suppress the immune system after organ transplant. Taking omega-6 fatty acids with cyclosporine may increase the immunosuppressive effects of this medication. It may also protect against kidney damage (a potential side effect from this medication).
Phenothiazines -- People taking a class of medications called phenothiazines to treat schizophrenia should not take evening primrose oil. Evening primrose oil may interact with these medications and increase the risk of seizures. The same may be true for other omega-6 supplements. These medications include:
Evening primrose oil; EPO; Linoleic acid; LA
Anandan C, Nurmatov U, Sheikh A. Omega 3 and 6 oils for primary prevention of allergic disease: systematic review and meta-analysis. Allergy. 2009 Jun;64(6):840-8. Epub 2009 Apr 7.
Attar-Bashi NM, Li D, Sinclair AJ. alpha-linolenic acid and the risk of prostate cancer. Lipids. 2004;39(9):929-32.
De Spirt S, Stahl W, Tronnier H, Sies H, Bejot M, Maurette JM, Heinrich U. Intervention with flaxseed and borage oil supplements modulates skin condition in women. Br J Nutr. 2009 Feb;101(3):440-5.
Freeman VL, Meydani M, Hur K, Flanigan RC. Inverse association between prostatic polyunsaturated fatty acid and risk of locally advanced prostate carcinoma. Cancer. 2004;101(12):2744-54.
Geppert J, Demmelmair H, Hornstra G, Koletzko B. Co-supplementation of healthy women with fish oil and evening primrose oil increases plasma docosahexaenoic acid, gamma-linolenic acid and dihomo-gamma-linolenic acid levels without reducing arachidonic acid concentrations. Br J Nutr. 2008 Feb;99(2):360-9.
Harris W. Omega-6 and omega-3 fatty acids: partners in prevention. Curr Opin Clin Nutr Metab Care. 2010; 13(2):125-9.
Kankaanpaa P, Nurmela K, Erkkila A, et al. Polyunsaturated fatty acids in maternal diet, breast milk, and serum lipid fattty acids of infants in relation to atopy. Allergy. 2001;56(7):633-638.
Kast RE. Borage oil reduction of rheumatoid arthritis activity may be mediated by increased cAMP that suppresses tumor necrosis factor-alpha. Int Immunopharmacol. 2001;1(12):2197-2199.
Kenny FS, Pinder SE, Ellis IO et al. Gamma linolenic acid with tamoxifen as primary therapy tn breast cancer. Int J Cancer. 2000;85:643-648.
Kris-Etherton PM, Taylor DS, Yu-Poth S, et al. Polyunsaturated fatty acids in the food chain in the United States. Am J Clin Nutr. 2000;71(1 Suppl):179S-188S.
Kupferer EM, Dormire SL, Becker H. Complementary and alternative medicine use for vasomotor symptoms among women who have discontinued hormone therapy. J Obstet Gynecol Neonatal Nurs. 2009 Jan-Feb;38(1):50-9.
Little C, Parsons T. Herbal therapy for treating rheumatoid arthritis. Cochrane Database Syst Rev. 2001;(1):CD002948.
Manjari V, Das UN. Effect of polyunsaturated fatty acids on dexamethasone-induced gastric mucosal damage. Prostaglandins Leukot Essent Fatty Acids. 2000;62(2):85-96.
Menendez JA, del Mar Barbacid M, Montero S, et al. Effects of gamma-linolenic acid and oleic acid on paclitaxel cytotoxicity in human breast cancer cells. Eur J Cancer. 2001;37:402-413.
Rakel D. Integrative Medicine. 2nd ed. Philadelphia, PA: Saunders, An Imprint of Elsevier: 2007.
Ramsden C, Gagnon C, Graciosa J, et al. Do omega-6 and trans fatty acids play a role in complex regional pain syndrome? A pilot study. Pain Med. 2010; 11(7):1115-25.
Richardson AJ, Puri BK. The potential role of fatty acids in attention-deficit/hyperactivity disorder. Prostaglandins Leukot Essent Fatty Acids. 2000;63(1/2):79-87.
Schirmer MA, Phinney SD. Gamma-linolenate reduces weight regain in formerly obese humans. J Nutr. 2007 Jun;137(6):1430-5.
Senapati S, Banerjee S, Gangopadhyay DN. Evening primrose oil is effective in atopic dermatitis: a randomized placebo-controlled trial. Indian J Dermatol Venereol Leprol. 2008 Sep-Oct;74(5):447-52.
Srivastava A, Mansel RE, Arvind N, Prasad K, Dhar A, Chabra A. Evidence-based management of Mastalgia: a meta-analysis of randomised trials. Breast. 2007 Oct;16(5):503-12. Epub 2007 May 16.
Surette ME, Stull D, Lindemann J. The impact of a medical food containing gamma-linolenic and eicosapentaenoic acids on asthma management and the quality of life of adult asthma patients. Curr Med Res Opin. 2008 Feb;24(2):559-67.
Weaver KL, Ivester P, Seeds M, Case LD, Arm JP, Chilton FH. Effect of dietary fatty acids on inflammatory gene expression in healthy humans. J Biol Chem. 2009 Jun 5;284(23):15400-7. Epub 2009 Apr 9.
Wakai K, Okamoto K, Tamakoshi A, Lin Y, Nakayama T, Ohno Y. Seasonal allergic rhinoconjunctivitis and fatty acid intake: a cross-sectional study in Japan. Ann Epidemiol. 2001;11(1):59-64.
Worm M, Henz BM. Novel unconventional therapeutic approaches to atopic eczema. Dermatology. 2000;201(3):191-195.
© 2011 University of Maryland Medical Center (UMMC). All rights reserved.
UMMC is a member of the University of Maryland Medical System,
22 S. Greene Street, Baltimore, MD 21201. TDD: 1-800-735-2258 or 1.866.408.6885