Gamma linolenic acid (GLA) is a dietary omega-6 fatty acid found in many plant oil extracts. Commercial products are typically made from seed extracts from evening primrose (average oil content 7-14%), blackcurrant (15-20%), borage oil (20-27%) and fungal oil (25%). GLA is not found in high levels in the diet. It has been suggested that some individuals may not convert the omega-6 fatty acid linoleic acid to longer chain derivatives, such as GLA, efficiently. Thus, supplementation with GLA-containing oils, such as borage oil and evening primrose oil, is occasionally recommended to increase GLA levels in the body.
GLA is available commonly as a dietary supplement and is sold over the counter in capsules or oil to treat a variety of conditions such as eczema, oral mucoceles (mucus polyps), hyperlipidemia (high cholesterol), depression, postpartum depression, chronic fatigue syndrome (CFS), psoriasis (chronic skin disease), muscle aches, and menopausal flushing.
There is currently good evidence for GLA treatment in rheumatoid arthritis, acute respiratory distress syndrome, and diabetic neuropathy (nerve damage). Little or no effect has been found in treatment of atopic dermatitis, attention deficit hyperactivity disorder (ADHD), cancer prevention, menopausal flushing, systemic sclerosis, and hypertension (high blood pressure). GLA has also been used to help with the body's response to tamoxifen in breast cancer patients.
Today, production and extraction of oil from evening primrose and borage is done by companies primarily in China, New Zealand, and England. Pharmaceutical licensing for GLA oil products has had only limited success worldwide.
Blackcurrant berry, blackcurrant dried leaf, blackcurrant oil, blackcurrant seed oil, borage oil (Borago officinalis), borage seed oil, BSO, bugloss, burage, burrage, casis, cassis, cureall EPO, Efamol, European black currant, European blackcurrant, evening primrose oil, fever plant, fungal oil, king's grosellero negro, hempseed oil, huile de hourrache, huile d'onagre, n-6 essential fatty acids, night willow-herb (Oenothera biennis), omega-6, omega-6 fatty acids, omega 6 oil, omega-6 oil, polyunsaturated fatty acid, primrose, PUFA, quinsy berries, ribes nero, ribes nigri folium (Ribes nigrum), scabish, siyah frenkuzumu (Turkish), squinancy berries, starflower, starflower oil, sun drop, zwarte bes.
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Diabetic neuropathy is a degenerative state of the nervous system that causes a variety of pain, tingling, burning, numbness and resultant loss of balance. The most common type, which is said to affect nearly half of diabetic patients, is distal polyneuropathy, which affects the peripheral nervous system in the legs, feet, arms, and hands. GLA may be a viable treatment, although additional study is needed in this area to confirm these findings.
Acute respiratory distress syndrome (ARDS)
Acute respiratory distress syndrome is respiratory failure in adults or children resulting in diffuse injury to the alveoli (tiny air scas) and lung capillary endothelium. GLA may promote the production of prostaglandin E1, an eicosanoid with known anti-inflammatory and immunoregulatory properties, which in turn may aid in treating ARDS. Additional study is warranted in this area.
Atopic dermatitis (AD) is one of the most common chronic inflammatory skin diseases, associated with at least 10% of children and 0.5-1% of adults. Studies in the past 20 years reveal minimal therapeutic improvements with GLA as therapy for atopic dermatitis, noted by only marginal to no improvement in inflammation and itching.
Attention deficit hyperactivity disorder (ADHD)
Clinical trials investigating the effect of GLA on symptoms associated with attention-deficit disorder are limited. There is no evidence of effectiveness of treatment with GLA, but more study is needed to confirm these results.
Blood pressure control
Preliminary study has investigated GLA on blood pressure changes. The evidence suggests that GLA may offer benefits in terms of blood pressure reduction; however, better-designed trials are required before definite conclusions can be made.
Cancer treatment (adjunct)
Preliminary study has indicated that GLA may act as a cytotoxic agent or at least as an adjunct agent to a chemotherapy regimen. However, human studies are conflicting and more study is needed before a strong conclusion can be made.
Few clinical trials have investigated the effect of GLA on immune responses in healthy human subjects. GLA, as blackcurrant seed oil, may offer some benefits. Further study is required before a definite conclusion can be made.
Cyclical mastalgia is breast pain experienced by women and typically associated with the menstrual cycle. The pain can vary in severity and usually occurs between ovulation and menstruation. Evidence for efficacy of GLA treatment is very limited, although since the 1990s, GLA has been recommended historically as a therapy.
Menopausal hot flashes
One study has examined the effect of GLA (evening primrose oil) on menopausal flushing. No improvement in the number of flushes was noted as compared with placebo. More clinical trials are needed before a strong recommendation can be made in this area.
Preliminary study has examined the effect of fatty acids, including GLA, on severity, frequency and duration of migraine attacks. Better-designed clinical trials are required before a strong recommendation can be made.
Some evidence from a clinical trial and observations of clinicians and dieticians has suggested that GLA and eicosapentaenoic acid (EPA) enhance the effects of calcium supplementation in elderly patients with senile osteoporosis. More clinical studies are required to produce results to determine effectiveness in diverse elderly and middle-age populations.
A study of GLA plus fish oil suggests there is a potential for benefit of edema (sweeling) in pregnancy. Clinical trials investigating the effects of GLA alone is required before a strong recommendation can be made.
Premenstrual syndrome (PMS)
A study using Efamol (containing GLA) suggests there may be benefit in terms of premenstrual syndrome symptoms. More information is needed in this area before a firm recommendation can be made.
Abnormalities of plasma fatty acids may be associated with pruritus (severe itching) in patients undergoing hemodialysis. GLA as evening primrose oil may improve skin conditions in these patients. Further clinical trials are required before a strong recommendation can be made.
Several clinical studies indicate significant therapeutic improvements in rheumatoid arthritis symptoms through reductions in scores on joint tenderness, joint swelling, physician global assessment and pain. Some studies also suggest that GLA may be a more tolerable alternative to the standard pain-reduction therapies, such as COX / COX2 inhibitors, and NSAIDs and their adverse events. However, there is some concern on dosage control and additional study is needed to make a strong recommendation in this area.
Currently, there is limited evidence showing that GLA is effective in treating Sjogren's syndrome. Additional study is needed before a firm recommendation can be made.
Currently, there is insufficient available evidence supporting the use of gamma linolenic acid for ulcerative colitis. Additional study is warranted.