Gamma-Linolenic acid

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The correct title of this article is gamma-Linolenic acid. The initial letter is shown capitalized due to technical restrictions.

gamma-Linolenic acid (GLA, C₁₈H₃₀O₂) is an omega-6 fatty acid that exists primarily in plant fats. In physiological literature, it is given the name 18:3 omega-6. Its systematic chemical name is all-cis-6,9,12-octadecatrienoic acid). Chemically, GLA is a carboxylic acid with an 18-carbon chain and three cis double bonds; the first double bond is located at the sixth carbon from the omega end. It is also sometimes called gamolenic acid.

GLA is a precursor of prostaglandin E1, which has a role in regulation of immune system function. It should not be confused with alpha-linolenic acid which is the omega-3 fatty acid found in flax seed.

The chemical structure of GLA showing physiological numbering (red) and chemical numbering (blue) conventions.

1 Sources
2 Benefits
3 History
4 References
5 See also

[edit] Sources

GLA is found in oenothera (evening primrose) oil, blackcurrant seed oil, borage oil, hemp seed oil, and Spirulina. Each contains varying amounts of the fatty acid, with borage oil usually being the most heavily concentrated form. All are widely available in pharmacies, health food stores, or online shops.

GLA is converted to dihomo-gamma-linolenic acid (DGLA), which is a precursor in the production of prostaglandins. Prostaglandins have a variety of roles in maintaining normal body function.

The belief that most people lack GLA is incorrect. GLA is produced by the body naturally from linoleic acid (LA). LA is consumed sufficiently in most diets, from such abundant sources as cooking oils and meats. However, a lack of GLA can occur when people grow older and their bodies become unable to produce it in sufficient quantities, or due to specific dietary deficiencies.

GLA can also form a lithium salt, increasing its solubility in water. The resulting compound is Li-GLA, also called lithium gammalinolenate. Li-GLA is currently in phase II clinical trials to determine whether it is useful in the treatment of HIV infections, since it has the ability to destroy HIV-infected T cells in vitro. It has a number of side-effects, including a reduction in hemoglobin, hematuria, gastrointestinal disturbance, fatigue and headache.

[edit] Benefits

Although GLA is an ω-6 fatty acid (which are generally pro-inflammatory) it is reported to have anti-inflammatory properties; see discussion at Essential fatty acid interactions#The paradox of dietary GLA.

As to health benefits, GLA is sometimes prescribed in the belief that has anti-inflammatory properties lacking some of the common side effects of other anti-inflammatory drugs. Herbal medicine advocates recommend GLA for autoimmune disorders, arthritis, eczema and PMS with noticeable results not expected for months. Research is ongoing, investigating GLA as a potential anticancer agent. Conflicting data is found for GLA in the treatment of eczema.^{[citation needed]} It is strongly advised that people should not take GLA together with anticonvulsant medication. It is also discouraged to take GLA over any sort of long term due to studies showing that it can lead to inflammation and other problems.^{[citation needed]} GLA is unique among the omega-6 polyunsaturated fatty acids (linoleic acid, GLA and arachidonic acid) in its potential to suppress tumor growth and metastasis. (Fan 1998)

[edit] History

In the Middle Ages, a folk remedy would be to take borage for any problems from rheumatism to heart disease.

Although there are alpha- and gamma- forms of linolenic acid, there is no beta form. One was once identified but it turned out to be an artifact of the original analytical process. (Gunstone)

[edit] References

Essential fatty acid metabolism and its modification in atopic eczema American Journal of Clinical Nutrition, Vol. 71, No. 1, 367S-372s, January 2000.

British Medical Journal summary of current findings on Evening Primrose Oil in the treatment of eczema

Obituary of David Horrobin - passionate promoter of evening primrose oil and author of the American Journal Clinical Nutrition report cited above.

Primrose Oil and Eczema: How Research Was Promoted and Suppressed Critical summary on Quackwatch of research on and marketing for evening primrose oil.

British Medical Journal: Efficacy and tolerability of borage oil in adults and children with atopic eczema.

Fan, Yang-Yi and Chapkin, Robert S. Importance of Dietary gamma-Linolenic Acid in Human Health and Nutrition A review article at The American Society for Nutrition; 9 September 1998. URL Retrieved 3 February 2006
Gunstone, Frank, Personal Communication at Peter Lapinskas' pages; URL Retrieved 3 February 2006