Gamma-linolenic acid (GLA) is an essential fatty acid (EFA) in the omega-6 family that is found primarily in plant-based oils. EFAs are essential to human health but cannot be made in the body. For this reason, they must be obtained from food. EFAs are needed for normal brain function, growth and development, bone health, stimulation of skin and hair growth, regulation of metabolism, and maintenance of reproductive processes.

Linoleic acid (LA), another omega-6 fatty acid, is found in cooking oils and processed foods and converted to GLA in the body. GLA is then broken down to arachidonic acid (AA) and/or another substance called dihomogamma-liolenic acid (DGLA). AA can also be consumed directly from meat, and GLA is available directly from evening primrose oil (EPO), black currant seed oil, and borage oil. Most of these oils also contain some linoleic acid.

The average North American diet provides more than 10 times the necessary amount of linoleic acid and tends to have too much omega-6 fatty acids compared to omega-3 fatty acids, another important class of EFAs. In fact, for optimum health, the ratio of omega-6 to omega-3 fatty acids should be between 1:1 and 4:1. The typical North American and Israeli diets are usually in the range of 11:1 to 30:1. This imbalance contributes to the development of long-term diseases such as heart disease, cancer, asthma, arthritis, and depression as well as, possibly, increased risk of infection.

Interestingly, not all omega-6 fatty acids behave the same. Linoleic acid (not to be confused with alpha-linolenic acid, which is in the omega-3 family) and arachidonic acid (AA) tend to be unhealthy because they promote inflammation, thereby increasing the risk of the diseases mentioned when consumed in excess. In contrast, GLA may actually reduce inflammation.

Much of the GLA taken from the oils mentioned or as a supplement is not converted to AA, but rather to DGLA. DGLA competes with AA and prevents the negative inflammatory effects that AA would otherwise cause in the body. Having adequate amounts of certain nutrients in the body (including magnesium, zinc, and vitamins C, B3, and B6) helps to promote the conversion of GLA to DGLA rather than AA.

It is important to know that many experts feel that the science supporting the use of omega-3 fatty acids to reduce inflammation and prevent diseases is much stronger than the information regarding use of GLA for these purposes.

GLA is the result of the body's first biochemical step in the transformation of the main essential fatty acid LA into important prostaglandins. Prostaglandins are essential to the proper functioning of each cell, while essential fatty acids formed from GLA are required for each cell's structure. Nature's most potent concentration of GLA comes in the form of borage seed oil (24%). A great deal of scientific research has been conducted with supplements rich in GLA, resulting in significant interest regarding the aforementioned health ailments, as well as those affected by pre-menstrual syndrome, benign breast disease, eczema, psoriasis, obesity, and vascular disorders.

GLA is found in the plant seed oils of evening primrose, black currant, borage, and fungal oils. Spirulina (often called blue-green algae) also contains GLA.

Because of the potential for side effects and interactions with medications, dietary supplements should be taken only under the supervision of a knowledgeable healthcare provider. Omega-6 supplements, including GLA and EPO, should not be used if you have a seizure disorder because there have been reports of these supplements inducing seizures. Borage seed oil, and possibly other sources of GLA, should not be used during pregnancy because they may be harmful to the fetus and induce early labor.Doses of GLA greater than 3,000 mg per day should be avoided because, at that point, production of AA (rather than DGLA) may increase.