Gamma-linolenic acid (GLA) is an omega-6 fatty acid that is a precursor to prostaglandin, a compound that is synthesized at the site of an infection or injury to mediate inflammation, fight cell damage, and regulate pain as part of the healing process. GLA has been touted for a variety of uses, from rheumatoid arthritis (RA) to diabetic neuropathy and beyond.
In addition to preventing or treating certain diseases and conditions like these, some say that GLA can work as a complement to other drugs to help alleviate symptoms.
Hemp seed oil, evening primrose oil, borage seed oil, and blackcurrant oil are among some of the highest sources of GLA. Available as a dietary supplement, GLA can also be found in significant quantities in oats, barley, spirulina, and hemp seeds.
What Is Gamma-Linolenic Acid Used For?
Practitioners of alternative medicine believe that gamma-linolenic acid can improve overall health by reducing the level of inflammatory proteins, known as cytokines, in the body.
Cytokines are essential to triggering inflammation, a natural immune response used to neutralize infections and heal injuries. However, if cytokine levels persistent—as can happen with obesity, high blood pressure, autoimmune diseases, and other chronic disorders—the unrelenting inflammation can cause progressive damage to cells and tissues.
In alternative medicine, GLA is believed to prevent or treat a wide range of unrelated health conditions, including:
- Asthma
- Atherosclerosis
- Cancer
- Diabetic neuropathy
- Eczema
- Chronic fatigue syndrome
- Depression
- High cholesterol
- Menopause symptoms
- Metabolic syndrome
- Psoriasis
- Rheumatoid arthritis
Few of these claims are strongly supported by research. Furthermore, most of the current research involves the use of primrose oil or borage oil rather than GLA supplements.
With that being said, there have been some promising findings. Here is some of what the current research says.
Eczema
Eczema is an umbrella term used to describe a group of skin conditions that occur in episodes and cause itching, redness, bumps, and scaling. Atopic dermatitis is one of the more common forms of eczema, alongside contact dermatitis and seborrheic dermatitis.
According to a 2014 study published in Advances in Therapy, a 4- to 6-gram (g) dose of evening primrose oil taken daily decreased the severity and recurrence of atopic dermatitis in 21 adults after 12 weeks of use. Higher doses conferred to better results, with 6 g of primrose oil delivering no less than 480 milligrams (mg) of GLA per day.
While promising, the conclusions were somewhat limited by the lack of a matched set of participants provided a placebo. Further research is needed.
Rheumatoid Arthritis
RA is an autoimmune form of arthritis characterized by persistent inflammation and the progressive damage of joints and other tissues. It is believed that, by tempering the underlying autoimmune inflammation, GLA may reduce the progression or severity of the disease.
According to the 2014 study in Evidence-Based Complementary and Alternative Medicine, the daily use of borage oil (on its own or with fish oil) reduced the need for disease-modifying antirheumatic drugs (DMARDs) commonly used to treat rheumatoid arthritis.
The 18-month trial involved 150 adults with rheumatoid arthritis who were assigned a daily dose of either borage oil capsules (corresponding to 1.8 g of GLA), fish oil capsules, or both. At the end of the study period, all three groups responded positively to therapy, with marked reductions in both disease activity and DMARD use.
Diabetic Neuropathy
Diabetic neuropathy is a nerve disorder characterized by painful pins-and-needles sensations. The condition is caused by the persistent inflammation associated with diabetes which gradually wears away the outer insulating membrane of nerve cells called the myelin sheath.
According to 2007 study in the Journal of Nutrition, mice with chemically-induced diabetes experienced better nerve function (including nerve signal velocity and blood flow to nerve cells) when given GLA for eight weeks compared to mice given docosahexaenoic acid found in fish oil. (Fish oil is a common complementary therapy for people with early-stage diabetic neuropathy.)
Interestingly, lower doses of GLA corresponded to better results. If the results can be replicated in humans, GLA could be considered a means of preventing a neurological condition that affects one in four people with type 2 diabetes.
Menopause
Borage oil and primrose oil have both been used for centuries to treat menopause symptoms. There is some evidence, albeit slight, of such benefits.
According to a 2013 study in Advanced Pharmaceutical Bulletin, female rats that had their ovaries removed experienced vaginal cornification after receiving GLA supplements for 21 days. Vaginal cornification occurs when rising levels of estrogen cause surface cells to become larger and flatter as part of the menstrual cycle.
This indicates that GLA has estrogen-like effects and suggests that GLA supplements may alleviate symptoms of menopause by overcoming low estrogen levels.
Further research is needed to establish whether the same dose used in rats—10 milligrams per kilogram (mg/kg) per day—might trigger the same effect in menopausal women. (For a 100-pound woman, that would translate to roughly 550 mg per day.)
Possible Side Effects
Gamma-linolenic acid is generally considered safe for use. Common side effects, which can particularly occur when first starting treatment, include:
- BelchingFlatulenceSoft stoolsDiarrhea
Symptoms tend to be mild and gradually resolve on their own as the body adapts to treatment. Persistent symptoms can usually be relieved by reducing the dose.
That said, you should avoid GLA is you have pre-existing diarrhea or any condition characterized by chronic diarrhea, such as diarrhea-predominant irritable bowel syndrome (IBS-D).
The safety of GLA in babies and younger children has not been established. As such, it best to avoid GLA while breastfeeding or in children under 7.
Interactions
Gamma-linolenic acid is known to slow blood clotting and may amplify the effects of blood thinners such as Coumadin (warfarin) and Plavix (clopidogrel), causing easy bruising and bleeding.
Due to its estrogen-like effects, GLA supplements should be avoided during pregnancy at they may increase the risk of miscarriage.
Whether you take these drugs or not, stop taking GLA supplements at least two weeks before a scheduled surgery to avoid excessive bleeding.
Taking GLA with phenothiazines used to treat schizophrenia and bipolar disorder may cause spontaneous seizures. Avoid GLA if you are taking Mellaril (thioridazine), Prolixin (fluphenazine), Stelazine (trifluoperazine), Thorazine (chlorpromazine), or any other phenothiazine-class antipsychotic.
If taking you are interested in taking GLA supplements for a specific health concern, let your healthcare provider know so that you can be monitored for side effects or interactions. Doing so also allows you to discuss other treatments that may be more appropriate for you as an individual.
Always advise your healthcare provider about any medications or other supplements you are taking, whether they are prescription, over-the-counter, nutritional, herbal, or recreational.
Dosage and Preparation
Most GLA supplements are available as soft gelatin capsules with doses ranging from 240 to 300 mg per capsule.
There are no universal guidelines for the appropriate use of gamma-linolenic acid. Dosages of up to 1,800 mg have been used with few notable side effects for up to 18 months in adults.
It should not be assumed that everyone needs such high doses of GLA or that lower doses are any less effective. As a rule of thumb, start with the lowest possible dose and increase gradually week-on-week as tolerated.
It is best to consult a pediatrician for a recommended dose for children.
What to Look For
Dietary supplements are not strictly regulated in the United States, making it hard to know which brands are good and which fall short. To better ensure quality and safety, opt for brands that have been voluntarily submitted for testing by an independent certifying body like the U.S. Pharmacopeia (USP), NSF International, or ConsumerLab.
Buying GLA supplements can often be confusing since the milligrams listed on the product label do not always correspond to the amount of GLA in the supplement.
For example, a product labeled “borage oil concentration GLA 1,000 mg” doesn’t necessarily mean that there are 1,000 milligrams of GLA in each capsule. Check the ingredient label; more often than not, it means that there are 1,000 milligrams of borage oil corresponding to around 240 mg of GLA.
If you are strictly vegetarian or vegan, check that the gelcap is made with a vegetable-based gelatin rather than one derived from beef or pork cartilage.
Always read the ingredient panel to ascertain how much GLA is delivered per capsule in milligrams—not percentages.
Most GLA supplements can be stored safely at room temperature or in the refrigerator. Keep the supplements away from direct sunlight, which can oxidize the fatty acids, and dispose of any gelcaps that are leaking or misshapen. Never use a supplement after its expiration date.
Other Questions
I saw “linoleic acid” on a supplement label. Is that the same thing as GLA?No. Most omega-6 fatty acids are derived from vegetable oils in the form of linoleic acid (LA). Once ingested, your body converts the LA to GLA, which is then converted into arachidonic acid and broken down into prostaglandins.
Do not confuse linoleic acid with gamma-linolenic acid. The amount of linoleic acid in each capsule is no indication of the amount of gamma-linolenic acid your body will render during metabolization.
Generally speaking, only GLA supplements will provide with you the exact amount of gamma-linolenic acid in milligrams per dose.
