Introduction

GLA is derived from linoleic acid, also known as omega-6 fatty acid, which is present in many common vegetable oils like safflower and sunflower. GLA is the precursor for many important prostaglandins, which are hormone-like substances that may affect blood thickness, skin and joint health, cholesterol levels, dilation and constriction of blood vessels, inflammation, and more. While omega-6 is readily available in the diet and consumed in large quantities in the American diet, many people are still deficient in GLA. Scientists think this is explained by the fact many oils containing omega-6 are hydrogenated, which can inhibit the conversion of omega-6 to GLA.

The primary dietary sources of GLA are borage oil, black currant seed oil, and evening primrose oil. GLA can also be produced in the body from omega-6 fatty acids.

Dosage Info

Dosage Range

Variable depending on the type of oil being used: evening primrose oil, 2 to 6 grams/day; borage oil, 1 to 6 grams/day; black currant seed oil, 2 to 10 grams/day.

Most Common Dosage

500-1,000mg daily.

Dosage Forms

Capsules or bottles of liquid oils.

Interactions and Depletions

Interactions

• mineral oil
• Bile acid sequestrants
• orlistat
• chitosan
• olestra
• Lipase inhibitor supplements
• Anticoagulant medications

Reported Uses

Because GLA is involved in the production of important prostaglandins, it may have a number of clinical applications. GLA supplementation may support alcoholics during withdrawal. Scientists believe alcohol blocks the enzymatic conversion of omega-6 to GLA. (1) Meanwhile, GLA may benefit diabetics. More specifically, it may stimulate the flow of blood to, and healthy function of nerves – thus reducing the risk of nervous disorders associated with diabetes. (2) , (3) GLA may effect growth and neurodevelopment, with no adverse effects in preterm infants. (4)

GLA may also help lower cholesterol levels. (5) Scientists have noted that GLA may be as much as 170 times more effective at lowering cholesterol than its precursor, omega-6. (6) Additionally, studies suggest that GLA may also support joint health and treat some symptoms of rheumatoid arthritis. (7) , (8) GLA may be useful in the treatment of several kinds of cancer. (9) , (10) , (11)

An inability to convert omega-6 to GLA may be linked to eczema. (12) , (13) Supplementation may reduce common symptoms such as itching, inflammation, scaling and dryness. (14) Finally, studies suggest that GLA may be an effective treatment for depression, irritability, breast pain and tenderness, and fluid retention associated with premenstrual syndrome. (15)

Toxicities & Precautions

Introduction

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General

People who take supplemental GLA are advised to take additional antioxidants, especially vitamin E, to protect against free radical damage to GLA in the body. (16)

Pregnancy / Breast Feeding

To date, the medical literature has not reported any adverse effects related to fetal development during pregnancy or to infants who are breast-fed. Yet little is known about the use of this dietary supplement while pregnant or breast-feeding. Therefore, it is recommended that you inform your healthcare practitioner of any dietary supplements you are using while pregnant or breast-feeding.

Age Limitations

To date, the medical literature has not reported any adverse effects specifically related to the use of this dietary supplement in children. Since young children may have undiagnosed allergies or medical conditions, this dietary supplement should not be used in children under 10 years of age unless recommended by a physician.

References

1. View Abstract: Horrobin DF. A biochemical basis for alcoholism and alcohol-induced damage including the fetal alcohol syndrome and cirrhosis: interference with essential fatty acid and prostaglandin metabolism. Med Hypotheses. Sep1980;6(9):929-42.
2. Jamal GA, et al. Gamma-linolenic acid in diabetic neuropathy. Lancet. 1986;Vol 1:1098.
3. View Abstract: Cameron NE, Cotter MA. Metabolic and vascular factors in the pathogenesis of diabetic neuropathy. Diabetes. Sep1997;46(Suppl 2):S31-7.
4. View Abstract: Fewtrell MS, Abbott RA, Kennedy K, et al. Randomized, double-blind trial of long-chain polyunsaturated fatty acid supplementation with fish oil and borage oil in preterm infants. J Pediatr. Apr2004;144(4):471-9.
5. View Abstract: Ishikawa T, et al. Effects of gammalinolenic acid on plasma lipoproteins and apolipoproteins. Atherosclerosis. Feb1989;75(2-3):95-104.
6. View Abstract: Horrobin DF, Manku MS. How do polyunsaturated fatty acids lower plasma cholesterol levels? Lipids. Aug1983;18(8):558-62.
7. View Abstract: Zurier RB, et al. Gamma-Linolenic acid treatment of rheumatoid arthritis. A randomized, placebo-controlled trial. Arthritis Rheum. Nov1996;39(11):1808-17.
8. View Abstract: Leventhal, et al. Treatment of rheumatoid arthritis with gammalinolenic acid. Ann Intern Med. Nov1993;119(9):867-73.
9. View Abstract: Das UN. Occlusion of infusion vessels on gamma-linolenic acid infusion. Prostaglandins Leukot Essent Fatty Acids. Jan2004;70(1):23-32.
10. View Abstract: Agombar A, Cooper AJ, Johnson CD. An aqueous formulation of gamma-linolenic acid with anti-proliferative action on human pancreatic cancer cell lines. Anticancer Drugs. Feb2004;15(2):157-60.
11. View Abstract: Karia C, Harwood JL, Morris AP, Heard CM. Simultaneous permeation of tamoxifen and gamma linolenic acid across excised human skin. Further evidence of the permeation of solvated complexes. Int J Pharm. Mar2004;271(1-2):305-9.
12. View Abstract: Manku MS, et al. Reduced levels of prostaglandin precursors in the blood of atopic patients: defective delta-6-desaturase function as a biochemical basis for atopy. Prostaglandins Leukot Med. Dec1982;9(6):615-28.
13. View Abstract: Horrobin DF. Essential fatty acid metabolism and its modification in atopic eczema. Am J Clin Nutr. Jan2000;71(1 Suppl):367S-72S.
14. View Abstract: Kerscher MJ, Korting HC. Treatment of atopic eczema with evening primrose oil: rationale and clinical results. Clin Investig. Feb1992;70(2):167-71.
15. View Abstract: Horrobin DF. The role of essential fatty acids and prostaglandins in the premenstrual syndrome. J Reprod Med. Jul1983;28(7):465-8.
16. View Abstract: Mainou-Fowler T, et al. Gamma-linolenic acid induces apoptosis in B-chronic lymphocytic leukaemia cells in vitro. Leuk Lymphoma. Jan2001;40(3-4):393-403.