Omega-6 fatty acids are essential fatty acids. They are necessary for human health, but the body cannot 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, and normal growth and development. As a type of polyunsaturated fatty acid (PUFA), omega-6s 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 to 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. Studies show that people who follow a Mediterranean-style 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), not to be confused with alpha-linolenic acid (ALA), which is an omega-3 fatty acid. Linoleic acid is converted to gamma-linolenic acid (GLA) in the body. It can then break down further 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.
Rheumatoid arthritis (RA)
Studies are mixed as to whether evening primrose oil (EPO) helps reduce symptoms of RA. Preliminary evidence suggests EPO 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 to 3 months for benefits to appear. It is unlikely that EPO 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 EPO 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.
Before you try GLA for allergies, work with your doctor to determine if it is safe for you. Then follow your allergy symptoms closely for any signs of 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. Most studies that used EPO 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. DO NOT add fatty acid supplements, or any supplements, to your breast cancer treatment regimen without your doctor's approval.
Evidence is mixed as to whether EPO can help reduce symptoms of eczema. Preliminary studies showed some benefit, but they were not well designed. Later studies that examined people who took EPO for 16 to 24 weeks found no improvement in symptoms. If you want to try EPO, talk to your doctor about whether it is safe for you.
High blood pressure (hypertension)
Preliminary evidence suggests that GLA may help reduce high blood pressure, either alone or in combination with omega-3 fatty acids found in fish oil, namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). 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, which is 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.
EPO has gained popularity as a way to treat hot flashes associated with menopause. But so far studies have been inconclusive. If you want to try EPO for hot flashes and night sweats, ask your doctor whether it is safe and right for you.
Breast pain (mastalgia)
Some evidence suggests that EPO may reduce breast pain and tenderness in people with cyclic mastalgia. It may also help reduce symptoms to a lesser extent in people with noncyclic mastalgia. However, it does not seem to be effective for severe breast pain.
Multiple sclerosis (MS)
EPO has been suggested as an additional treatment (along with standard therapy) for MS, although there is no scientific evidence that it works. People with MS who want to add EPO to their treatment regimens should talk with a health care provider.
Some studies suggest that people who do not get enough 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 improve 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 to 4:1, omega-6 to omega-3, and some health educators advocate even lower ratios. Omega-6 fatty acids can be found in sunflower, safflower, soy, sesame, and corn oils. The average diet provides plenty of omega-6 fatty acids, so supplements are usually not necessary. People with specific conditions, such as eczema, psoriasis, arthritis, diabetes, or breast tenderness (mastalgia) may want to ask their doctors about taking omega-6 supplements.
Omega-6 fatty acids are available in supplemental oils that contain linoleic acid (LA) and GLA, such as EPO (Oenothera biennis) and black currant (Ribes nigrum) oils. Spirulina (often called blue-green algae) also contains GLA.
How to Take It
The average diet provides sufficient omega-6 fatty acids, so supplementation is usually not necessary unless you are treating a specific condition, such as:
- Breast tenderness (mastalgia)
The dose and form of omega-6 fatty acids to be supplemented depends on many factors, including:
- The condition being treated
- 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, you should take dietary supplements only under the supervision of a knowledgeable health care provider.
DO NOT take omega-6 fatty acids if you have a seizure disorder because there have been reports of these supplements causing seizures. Several reports describe seizures in people taking EPO. Some of these seizures developed in people with a previous seizure disorder, or in people taking EPO in combination with anesthetics. People who plan to undergo surgery requiring anesthesia should stop taking EPO 2 weeks ahead of time.
Borage seed oil, and possibly other sources of 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 EPO 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 fats found in corn oil, promote the growth of prostate tumor cells. Until more research is done, health 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 talking to your health care provider first.
Blood-thinning medications: People taking blood thinners, including warfarin (Coumadin) or clopidogrel (Plavix), should not take omega-6 fatty acid supplements without a doctor's supervision. Omega-6 and omega-3 fatty acids may increase the risk of bleeding.
Ceftazidime: GLA may increase the effectiveness of ceftazidime. Ceftazidime, 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 transplantation. Taking omega-6 fatty acids with cyclosporine may increase the immunosuppressive effects of this medication. It may also protect against kidney damage, which is a potential side effect from cyclosporine.
Phenothiazines: People taking a class of medications called phenothiazines to treat schizophrenia should not take EPO. EPO may interact with these medications and increase the risk of seizures. The same may be true for other omega-6 supplements. These medications include:
- Chlorpromazine (Thorazine)
- Fluphenazine (Stelazine)
- Perphenazine (Trilafon)
- Promethazine (Compazine)
- Thioridazine (Mellaril)
Allen KL, Mori TA, Beilin L, Byrne SM, Hickling S, Oddy WH. Dietary intake in population-based adolescents: support for a relationship between eating disorder symptoms, low fatty acid intake and depressive symptoms. J Hum Nutr Diet. 2013;26(5):459-69.
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 Lorgeril M, Salen P. New insights into the health effects of dietary saturated and omega-6 and omega-3 polyunsaturated fatty acids. BMC Med. 2012;10:50.
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. 3rd ed. Philadelphia, PA: Elsevier Saunders; 2012.
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.
Simopoulos AP. Evolutionary aspects of diet: the omega-6/omega-3 ratio and the brain. Mol Neurobiol. 2011;44(2):203-15.
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.
Sumich AL, Matsudaira T, Heasman B, et al. Fatty acide correlates of temperament in adolescent boys with attention deficit hyperactivity disorder. Prostaglandins Leukot Essent Fatty Acids. 2013;88(6):431-6.
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.
Townsend. Sabiston Textbook of Surgery. 19th ed. Philadelphia, PA: Elsevier Saunders; 2012.
Vanhala M, Saltevo J, Soininen P, et al. Serum omega-6 polyunsaturated fatty acids and the metabolic syndrome: a longitudinal population-based cohort study. Am J Epidemiol. 2012;176(3):253-60.
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.