Gamma-Linolenic Acid (GLA) Usage

GLA has shown some promise for the treatment of diabetic neuropathy , ¹ a complication of diabetes . This condition consists of pain and/or numbness due to progressive nerve damage. However, supporting evidence that GLA is effective for this use is quite limited.

Perhaps the most common use of GLA has been as a treatment for eczema . It was once widely dispensed for this purpose by the British healthcare system, but the balance of the evidence indicates that for eczema, GLA is just a placebo treatment. ² GLA is also a popular treatment for cyclic mastalgia (breast pain that cycles with the menstrual period), but the evidence regarding its effectiveness is more negative than positive. ³ GLA is additionally said to be useful for general premenstrual syndrome (PMS) symptoms, but the supporting evidence for this use is very weak. ⁴ Despite many positive anecdotes, ⁵ GLA has failed to prove effective for attention deficit and hyperactivity disorder (ADHD) . ⁶ One study that used GLA plus fish oil did find weak evidence of benefits. ⁷ Extremely weak evidence hints that evening primrose oil might be more effective for ADHD if combined with zinc, but this is more of an untested hypothesis than a conclusion. ⁸ GLA has been studied for numerous other conditions, such as rheumatoid arthritis , ^{9 10 11} Raynaud's phenomenon (a condition in which the fingers and toes react to cold in an exaggerated way), ¹² weight loss , ¹³ ulcerative colitis , ¹⁴ kidney stones , ¹⁵ multiple sclerosis , ¹⁶ and increasing the effectiveness of the drug tamoxifen in the treatment of breast cancer . ¹⁷ Note: Individuals undergoing treatment for cancer should not take GLA (or any other supplement) except under physician supervision.

Other studies have investigated the potential benefits of combination treatment using GLA and fish oil. Conditions studied include osteoporosis , ¹⁸ chronic fatigue syndrome , ¹⁹ periodontitis (gum disease), ²⁰ and Huntington’s disease. In these trials, some promising (but far from definitive) results have been seen. However, this combination therapy has failed to prove effective for cyclic mastalgia . ²¹ GLA is sometimes suggested as a treatment for tardive dyskinesia , but two double-blind studies have failed to find it helpful for this disorder. ²² GLA has also failed to prove effective for the itching caused by kidney dialysis. ²³ There is some evidence that GLA may benefit patients with eye problems. One randomized trial indicated that orally administered evening primrose oil was more effective than olive oil (placebo) at reducing dry eye symptoms and improving comfort in users of soft contact lens. ²⁴ In addition, Sjogren's syndrome , an autoimmune condition in which the immune system destroys moisture-producing glands, often causes dry eyes due to lack of tears. One small double-blind study found that a combination of GLA and the omega-6 fatty acid linoleic acid (found in many vegetable oils) may improve dry eye symptoms in Sjogren's. ²⁵ Finally, patients who undergo laser surgery for vision correction (photorefractive keratectomy) are sometimes left with a hazy appearance to their cornea. Another small randomized trial found some potential benefit of a supplement containing omega-6 fatty acids in preventing this complication. ²⁶ Thus far, we've mentioned only a fraction of the conditions for which GLA has been proposed as a treatment. Others include: asthma , allergies , bursitis , endometriosis , heart disease , irritable bowel syndrome , prostate cancer , benign prostatic hyperplasia (BPH) , and Sjogren's disease . However, none of these potential uses has as yet been scientifically evaluated to any significant extent.