Gamma-Linolenic Acid (GLA)
• Omega-6 Oil(s), Omega-6 Fatty Acids, Sources of GLA Include: Black Currant Seed Oil, Borage Oil, Evening Primrose Oil
• GLA Alone:
GLA (gamma-linolenic acid) is one of the two main types of
essential fatty acids
These are "good" fats that are as necessary for your health as vitamins. Specifically, GLA is an omega-6 fatty acid. (For more information on the other major category of essential fatty acids, omega-3, see the article on
The body uses essential fatty acids to make various prostaglandins and leukotrienes. These substances influence inflammation and pain; some of them increase symptoms, while others decrease them. Taking GLA may swing the balance over to the more favorable prostaglandins and leukotrienes, making it helpful for diseases that involve inflammation.
There is some evidence that GLA may be helpful for
The body ordinarily makes all the GLA it needs from linoleic acid, an omega-6 essential fatty acid found in many foods. In certain circumstances, however, the body may not be able to convert linoleic acid to GLA efficiently. These include advanced age, diabetes, high alcohol intake, eczema, cyclic mastitis, viral infections, excessive saturated fat intake, elevated cholesterol levels, and deficiencies of vitamin B 6 , zinc, magnesium, biotin, or calcium. 1-5
Very little GLA is found in the diet. Borage oil is the richest supplemental source (17% to 25% GLA), followed by black currant oil (15% to 20%) and evening primrose oil (7% to 10%). Borage and evening primrose are the most common sources used in studies.
It is commonly stated that people require a certain optimum ratio of omega-3 to omega-6 fatty acids in the diet; however, there is no real evidence that this is true, and some evidence that it is false.
The typical dosage of GLA when it is used in hopes of alleviating cyclic mastalgia or eczema is about 200 to 400 mg daily (about 2 to 4 g of evening primrose oil or 1 to 2 g borage oil). Diabetic neuropathy is typically treated with about 400 to 600 mg daily (about 4 to 6 g of evening primrose or 2 to 3 g of borage oil), and in rheumatoid arthritis doses as high as 2,000 to 3,000 mg have been tried. (Doses this high can only be obtained from purified GLA, as one would need impractically high doses of evening primrose oil or borage oil to get enough).
GLA should be taken with food. Full benefits (if there are any) may take more than 6 months to develop.
GLA has shown some promise for the treatment of
Perhaps the most common use of GLA has been as a treatment for
GLA is also a popular treatment for
Despite many positive anecdotes,
GLA has been studied for numerous other conditions, such as
Other studies have investigated the potential benefits of combination treatment using GLA and fish oil. Conditions studied include
GLA is sometimes suggested as a treatment for tardive
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.
Thus far, we've mentioned only a fraction of the conditions for which GLA has been proposed as a treatment. Others include:
What Is the Scientific Evidence for Gamma-Linolenic Acid?
is a gradual degeneration of nerves caused by diabetes. There is some evidence that GLA can be helpful, if you give it long enough to work. In one double-blind, placebo-controlled study, 111 people with mild diabetic neuropathy received either 480 mg daily of GLA or placebo.
Despite the fact that GLA (usually as evening primrose oil) is widely used in Europe to treat
A 1989 review of the literature found significant benefit in the 9 double-blind controlled studies performed to that date, all involving evening primrose oil.
Improvements in symptoms were also seen in a later double-blind study of 48 children with eczema.
However, more recent and better conducted research has failed to find any benefit. For example, a 16-week, double-blind study involving 58 children with eczema found no difference between the effects of evening primrose oil and placebo (substantial improvements were seen, but to the same extent for placebo and evening primrose oil).
GLA taken orally from borage oil has also failed to prove effective. In a 24-week, double-blind study of 160 adults with eczema, the treatment provided no greater benefits than placebo.
Finally, in a double-blind, placebo-controlled study of 118 infants at high risk for developing eczema in the future, a GLA supplement made from borage oil failed to provided a significant protective effect.
However, an interesting double-blind study tested the use of undershirts coated with borage oil for treatment of
We do not know the cause of cyclic mastalgia, but some researchers believe that it is associated with an imbalance of fatty acids in the body.
The main supporting evidence comes from three controlled studies that appeared to find benefit.
Other Premenstrual Symptoms
Although several small studies suggest that GLA as evening primrose oil is helpful in reducing overall
According to many studies, fish oil, a source of omega-3 essential fatty acids, improves symptoms of
Other small studies have found similar results.
High dosages of evening primrose oil may be useful for
There is some evidence that essential fatty acids may enhance the effectiveness of calcium for the treatment or prevention of
However, a 12-month, double-blind trial of 42 postmenopausal women found no benefit.
The explanation for the discrepancy may lie in the differences between the women studied. The first study involved women living in nursing homes, while the second studied healthier women living on their own. The latter group of women may have been better nourished and already received enough essential fatty acids in their diet.
Attention Deficit and Hyperactivity Syndrome
Based on evidence that essential fatty acids are necessary for the proper development of brain function in growing children, essential fatty acids have been tried for the treatment of
Evening primrose oil by itself was found no better than placebo in a double-blind, placebo-controlled trial.
A 12-week, double-blind study that enrolled 100 significantly
Another double-blind trial, involving 47 people, tested the unusual hypothesis that evening primrose might only work in individuals with a family history of obesity.
Considering the contradictory nature of this evidence, more research is necessary to determine whether evening primrose oil is really useful for weight loss.
Most of the safety information we have regarding GLA comes from experience with evening primrose oil.
Animal studies suggest that evening primrose oil is completely nontoxic and noncarcinogenic. 77
Early reports suggested the possibility that GLA might worsen temporal lobe epilepsy, but there has been no later confirmation.
The maximum safe dosage of GLA for young children, pregnant or nursing women, or those with severe liver or kidney disease has not been established.
8. Mansel RE, Gateley CA, Harrison BJ, et al. Effects and tolerability of n-6 essential fatty acid supplementation in patients with recurrent breast cysts—a randomized double-blind placebo-controlled trial. J Nutr Med. 1990;1:195-200.
14. Morse PF, Horrobin DF, Manku MS, et al. Meta-analysis of placebo-controlled studies of the efficacy of Epogam in the treatment of atopic eczema. Relationship between plasma essential fatty acid changes and clinical response. Br J Dermatol. 1989;121:75-90.
20. Yoshimoto-Furuie K, Yoshimoto K, Tanaka T, et al. Effects of oral supplementation with evening primrose oil for six weeks on plasma essential fatty acids and uremic skin symptoms in hemodialysis patients. Nephron. 1999;81:151-159.
38. Warren G, McKendrick M, Peet M. The role of essential fatty acids in chronic fatigue syndrome. A case-controlled study of red-cell membrane essential fatty acids (EFA) and a placebo-controlled treatment study with high dose of EFA. Acta Neurol Scand. 1999;99:112-116.
41. Bassey EJ, Littlewood JJ, Rothwell MC, et al. Lack of effect of supplementation with essential fatty acids on bone mineral density in healthy pre- and postmenopausal women: two randomized controlled trials of EfacalŴ v. calcium alone. Br J Nutr. 2000;83:629-635.
42. Richardson AJ, McDaid AM, Calvin CM, et al. Reduced behavioural and learning problems in children with specific learning difficulties after supplementation with highly unsaturated fatty acids: a randomized double-blind placebo-controlled trial. Presented at: 2nd Forum of European Neuroscience Societies; July 24-28, 2000; Brighton, United Kingdom.
47. Mansel RE, Gateley CA, Harrison BJ, et al. Effects and tolerability of n-6 essential fatty acid supplementation in patients with recurrent breast cysts—a randomized double-blind placebo-controlled trial. J Nutr Med. 1990;1:195-200.
53. Stevens EJ, Lockett MJ, Carrington AL, et al. Essential fatty acid treatment prevents nerve ischaemia and associated conduction anomalies in rats with experimental diabetes mellitus. Diabetologia. 1993;36:397-401.
57. Morse PF, Horrobin DF, Manku MS, et al. Meta-analysis of placebo-controlled studies of the efficacy of Epogam in the treatment of atopic eczema. Relationship between plasma essential fatty acid changes and clinical response. Br J Dermatol. 1989;121:75-90.
59. Biagi PL, Bordoni A, Hrelia S, et al. The effect of gamma-linolenic acid on clinical status, red cell fatty acid composition and membrane microviscosity in infants with atopic dermatitis. Drugs Exp Clin Res. 1994;20:77-84.
65. Yoshimoto-Furuie K, Yoshimoto K, Tanaka T, et al. Effects of oral supplementation with evening primrose oil for six weeks on plasma essential fatty acids and uremic skin symptoms in hemodialysis patients. Nephron. 1999;81:151-159.
73. Bassey EJ, Littlewood JJ, Rothwell MC, et al. Lack of effect of supplementation with essential fatty acids on bone mineral density in healthy pre- and postmenopausal women: two randomized controlled trials of EfacalŴ v. calcium alone. Br J Nutr. 2000;83:629-635.
74. Richardson AJ, McDaid AM, Calvin CM, et al. Reduced behavioural and learning problems in children with specific learning difficulties after supplementation with highly unsaturated fatty acids: a randomized double-blind placebo-controlled trial. Presented at: 2nd Forum of European Neuroscience Societies; July 24-28, 2000; Brighton, United Kingdom.
82. Middleton SJ, Naylor S, Woolner J, et al. A double-blind, randomized, placebo-controlled trial of essential fatty acid supplementation in the maintenance of remission of ulcerative colitis. Aliment Pharmacol Ther. 2002;16:1131-1135.
83. Mansel RE, Pye KJ, Hughes LE. A controlled trial of evening primrose oil (Efamol) in cyclic premenstrual matalgia. Abstract 47. Proceedings of the 2nd International Symposium on Premenstrual, Postpartum, and Meonopausal Mood Disorders; 1987; Kiawah Island, SC.
85. Blommers J, De Lange-De Klerk ES, Kuik DJ, et al. Evening primrose oil and fish oil for severe chronic mastalgia: A randomized, double-blind, controlled trial. Am J Obstet Gynecol. 2002;187:1389-1394.
86. Van Gool CJ, Thijs C, Henquet CJ, et al. Gamma-Linolenic acid supplementation for prophylaxis of atopic dermatitis—a randomized controlled trial in infants at high familial risk. Am J Clin Nutr. 2003;77:943-951.
87. Takwale A, Tan E, Agarwal S, et al. Efficacy and tolerability of borage oil in adults and children with atopic eczema: randomised, double blind, placebo controlled, parallel group trial. BMJ. 2003;327:1385.
89. Arnold LE, Pinkham SM, Votolato N. Does zinc moderate essential fatty acid and amphetamine treatment of attention-deficit/hyperactivifty disorder? J Child Adolesc Psychopharmacol. 2000;10:111-117.
92. Kanehara S, Ohtani T, Uede K, et al. Clinical effects of undershirts coated with borage oil on children with atopic dermatitis: A double-blind, placebo-controlled clinical trial. J Dermatol. 2007;34:811-815.
Last reviewed April 2009 by EBSCO CAM Review Board
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