The Health Benefits of Gamma-Linolenic Acid

A type of omega-6 tatty acid that can help fight inflammation and pain

Gamma-linolenic acid (GLA) is a type of fatty acid found in certain vegetable oils that is believed to have therapeutic properties. Classified as an omega-6 fatty acid, GLA is converted by the body into substances that fight inflammation and cell damage. Hemp seed oil, evening primrose oil, borage seed oil, and blackcurrant oil are among some of the highest sources of GLA.

In the body, GLA is a precursor of a compound known as prostaglandin. Prostaglandins are synthesized at the site of an infection or injury whose role it is to mediate inflammation and pain as part of the healing process.

Some people believe that these properties can prevent or treat certain diseases or work in complement to other drugs to alleviate symptoms. Available as a dietary supplement, GLA can also be found in significant quantities in oats, barley, spirulina, and hemp seeds.

Gamma-linolenic acid softgels
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Health Benefits

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:

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 finding Here is some of what the current research says.


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-gram to 6-gram 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 grams of primrose oil delivering no less than 480 milligrams of GLA per day.

While promising, the conclusions were somewhat by the lack of a control group (a matched set of participants provided a placebo). Further research is needed.

Rheumatoid Arthritis

Rheumatoid arthritis 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 grams 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, it could provide the means to prevent a neurological condition that affects one in four people with type 2 diabetes.


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 were ovariectomized (had their ovaries removed) experience 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 kilograms per day—might trigger the same effect in menopausal women. (For a 100-pound woman, that would translate to roughly 550 milligrams per day.)

Possible Side Effects

Gamma-linolenic acid is generally considered safe for use. Doses of 1,800 milligrams (mg) per day have been used in adults for 18 months with few notable side effects. GLA has also been studied in children as young as seven.

Common side effects include belching, flatulence, soft stools, and diarrhea, particularly when first starting treatment. 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.

Due to its estrogen-like effects, GLA supplements should be avoided during pregnancy at they may increase the risk of miscarriage. The safety of GLA in babies and younger children has also not been established. As such, it best to avoid GLA while breastfeeding or in children under 7.

Avoid any GLA supplement containing borage oil if you are pregnant or trying to get pregnant. Borage oil contains pyrrolizidine alkaloids that are contraindicated in pregnancy due to the risk of birth defects.

You should also avoid GLA is you have diarrhea or any condition characterized by chronic diarrhea, such as diarrhea-predominant irritable bowel syndrome (IBS-D).


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. 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.

To avoid interactions, always advise your doctor about any medications 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 milligrams to 300 milligrams per capsule.

There are no universal guidelines for the appropriate use of gamma-linolenic acid. Dosages of up to 1,800 milligrams have been used safely for us up to 18 months in adults.

This shouldn't suggest that everyone needs such high doses or that lower doses are any less effective than higher ones. As a rule of thumb, start with the lowest possible dose and increase gradually week-on-week as tolerated.

If taking GLA supplements for a specific health concern, let your doctor 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.

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.

Always read the ingredient panel to ascertain how much GLA is delivered per capsule in milligrams (mg) and not percentages.

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.

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

How is gamma-linolenic acid different from linoleic acid?

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.

When reading a product label, 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.

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  1. Raz R, Carasso RL, Yehuda A. The influence of short-chain essential fatty acids on children with attention-deficit/hyperactivity disorder: a double-blind placebo-controlled study. J Child Adol Psychopharmacol. 2009;19(2):167-77. doi:10.1089/cap.2008.070

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