Gamma-linolenic acid (GLA) is an omega-6 fatty acid. The body converts linoleic acid to gamma-linolenic acid and then to arachidonic acid (AA). 

You can get gamma-linolenic acid from several plant-based oils, including evening primrose oil (EPO), borage oil, and black currant seed oil. Most of these oils also contain some linoleic acid.

Gamma-linolenic acid contains 18 carbons and 3 double bonds. It is synthesized from linoleic acid 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.

What are Omega-6 fatty acids?

Omega-6 fatty acids are considered essential fatty acids. They are necessary for human health, but the body cannot make them. You have to get them through food. Along with omega-3 fatty acids, omega-6 fatty acids play a crucial role in brain function, and normal growth and development. Also known as polyunsaturated fatty acids (PUFAs), they help stimulate skin and hair growth, maintain bone health, regulate metabolism, and maintain the reproductive system.

There are several different types of omega-6 fatty acids. Most omega-6 fatty acids in the diet come from vegetable oils in the form of linoleic acid (LA). 

Balance of omega-3 and omega-6 fatty acids:

A healthy diet contains a balance of omega-3 and omega-6 fatty acids. Omega-3 fatty acids help reduce inflammation while some omega-6 fatty acids promote inflammation. The typical American diet contains 14 to 25 times more omega-6 fatty acids than omega-3 fatty acids. Many physicians blame this high rate of omega-6 to omega-3 fatty acids for the large number of inflammatory diseases in the American population.

Not all omega-6 fatty acids behave the same. Linoleic acid and arachidonic acid (AA) tend to promote inflammation. Gamma-linolenic acid, on the other hand, may actually reduce inflammation. Some studies even suggest that GLA protects DNA.

The body converts much of the gamma-linolenic acid to a substance called DGLA that fights inflammation. Having enough of certain nutrients in the body (including magnesium, zinc, and vitamins C, B3, and B6) helps promote the conversion of gamma-linolenic acid to DGLA.

Many experts find the science supporting the use of omega-3 fatty acids to reduce inflammation and prevent diseases to be much stronger than that supporting gamma-linolenic acid.

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Possible treatment options:

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.

Questions and concerns:

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:

- https://pubmed.ncbi.nlm.nih.gov/17168669/
- https://pubmed.ncbi.nlm.nih.gov/23460824/
- https://pubmed.ncbi.nlm.nih.gov/9732298/
- https://pubmed.ncbi.nlm.nih.gov/27083549/