γ-linolenic acid (GLA) is an omega-6 fatty acid containing 18 carbons and 3 double bonds (18:3n6).
It is synthesized from LA by adding a double bond using the delta-6-desaturase enzyme. This enzymatic reaction is very slow and further impaired in vitamin and mineral deficiencies such as zinc and cobalt.
Stress, smoking, alcohol, and systemic inflammatory conditions can also slow this conversion.
Since the synthesis of GLA is not efficient, dietary intake of organ meats may be considered to raise GLA levels. Also, many people supplement with GLA-containing products such as borage oil, black currant, and evening primrose. Primrose and borage oil supplementation have been studied as an effective treatment for many conditions such as rheumatoid arthritis, dermatitis, and diabetic neuropathy. They have been shown to decrease inflammation, improve bone health, regulate lipid metabolism, and have beneficial effects on the skin.
But, whether it’s the GLA component that is beneficial or GLA’s downstream fatty acid metabolite is difficult to determine.
The clinical importance of GLA is in its rapid conversion to its downstream fatty acid dihomo-gamma-linolenic acid (DGLA) which is anti-inflammatory. GLA itself, however, does have physiologic importance. It has been shown to exert some tumoricidal activity in various cancers and to inhibit metastases.
GLA has been studied for its clinical importance in neurovascular deficits in diabetes and has been shown to normalize nerve conduction velocity and endoneurial blood flow.
There is some concern regarding GLA supplementation leading to rapid conversion through DGLA to arachidonic acid. Supplementing the omega-3s EPA or DHA may help to mitigate the effects since there is enzymatic competition for the delta-5-desaturase enzyme. This enzyme is responsible for both AA production and EPA metabolism.
References:
Das UN. Arachidonic acid in health and disease with focus on hypertension and diabetes mellitus: A review. Journal of advanced research. 2018;11:43-55.
- Kapoor R, Huang Y-S. Gamma linolenic acid: an antiinflammatory omega-6 fatty acid. Current pharmaceutical biotechnology. 2006;7(6):531-534.
- Tasset-Cuevas I, Fernández-Bedmar Z, Lozano-Baena MD, et al. Protective effect of borage seed oil and gamma linolenic acid on DNA: in vivo and in vitro studies. PloS one. 2013;8(2):e56986-e56986.
- Fan Y-Y, Chapkin RS. Importance of Dietary γ-Linolenic Acid in Human Health and Nutrition. The Journal of Nutrition. 1998;128(9):1411-1414.
- Sergeant S, Rahbar E, Chilton FH. Gamma-linolenic acid, Dihommo-gamma linolenic, Eicosanoids and Inflammatory Processes. European journal of pharmacology. 2016;785:77- 86.
g-Linolenic (GLA) 18:3 n6
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