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.
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,
- 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.
Decreased intake of the essential LA can result in low levels. Also decreased conversion by the delta-6-desaturase enzyme can result in low levels of GLA due to lack of vitamin and mineral cofactors or SNPs in the enzyme.
Potential treatment options:
The competition for use of delta-6-desaturase by the omega-3s should also be considered. Due to the important clinical implications of GLA and subsequent DGLA formation as outlined, supplementation with evening primrose, borage oil, and black currant may be beneficial.
Signs and symptoms of alpha or gamma linolenic acid insufficiency:
- growth retardation
- impairment of vision
- learning disability
- poor coordination
- tingling in arms/legs
- behavioral changes
- mental disturbances
- low metabolic rate
- high blood pressure
- immune dysfunction
Elevations are seen with supplementation of borage oil, primrose, and black currant. Additionally, the conversion to DGLA requires the elongase enzyme. Lack of vitamin and mineral cofactors, enzymatic SNPs, or competition for use of the enzyme by omega-3 fatty acids may contribute to elevated GLA. It should also be emphasized that smoking, alcohol, and systemic inflammation can slow the elongase enzyme and conversion to DGLA.
As noted above, GLA has important clinical implications. The issues of safety have been investigated and GLA appears to be nontoxic. Limited cases of soft stools, belching, and abdominal bloating have been reported. Long-term human studies show that up to 2.8 g/d are well tolerated. However, the possibility exists that GLA will be metabolized through to DGLA and then increase arachidonic acid causing inflammation.
The addition of EPA or DHA may help to mitigate these effects.
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