Gamma-linoleic acid or GLA is among nature’s top beauty remedies. It’s an anti-inflammatory omega-6 fatty acid, famous for enhancing weight loss and soothing irritated skin. A number of traditionally-used herbs are rich in it. Read on to find out if GLA lives up to its reputation and how to get more of it from food.

What Is GLA?

Gamma-linolenic acid (GLA) is an omega-6 polyunsaturated fatty acid mainly found in plant seeds. Although sometimes called essential, you don’t need to get it from food since your body can make it from linoleic acid [1+, 2+].

Researchers first discovered GLA in a North American plant (evening primrose) used by the natives as a food and remedy for laziness, obesity, piles, and boils. Early settlers took it to Europe, where it became a popular remedy known as “King’s cure-all” [3+].

Uses

The FDA doesn’t approve GLA for any conditions, but considers it generally recognized as safe (GRAS). GLA and oils containing it are mainly used for [4+]:

  • Weight loss
  • Eczema, acne, and skin care
  • Inflammatory conditions
  • Dry eyes
  • Hair and nail care

Some people also recommend GLA for the following conditions, although evidence goes against them:

Food Sources of GLA

Your body makes GLA from the linoleic acid you take in through food. Most adults on a typical Western diet get enough linoleic acid from vegetable oils, nuts, and seeds [2+]:

However, some people have trouble converting linoleic acid to GLA, including the elderly and those with [2+]:

  • Nutritional deficiencies
  • Inflammatory conditions
  • Hormonal imbalances
  • High blood pressure
  • Diabetes
  • Stress
  • Excessive intake of trans fats and alcohol

If any of the above factors apply to you, getting more pure GLA might be a good idea.

GLA is found in small amounts in organ meat, especially liver, but its main sources are seed oils of [1+]:

  • Borage (18-26% GLA)
  • Black currant (15-20%)
  • Evening primrose (7-10%)
  • Hemp (3%)

Babies usually get enough fatty acids from breast milk, which contains both GLA (0.1-0.9%) and linoleic acid (6-17%) [10+].

Gamma Linolenic Acid vs Conjugated Linoleic Acid

Don’t confuse GLA with conjugated linoleic acid or CLA. Although it sounds similar, CLA is linoleic acid with different orientation in space. As such, it has distinct health effects. CLA is found in meat and dairy products, but is better known as a weight-loss supplement for bodybuilders [11+, 12+].

Health Benefits of GLA

How it Works

Your body takes the linoleic acid you get from food and turns it into GLA. Next, GLA is transformed into a longer molecule (DGLA), which is stored in cell membranes [2+].

DGLA stays in cell membranes until a signal triggers its release: inflammation, and an enzyme called phospholipase A2. The cue splits DGLA into two anti-inflammatory molecules: PGE1 and thromboxane A1 [13, 2+].

These two molecules block a long list of pro-inflammatory pathways and messengers (NF-kB, AP-1, ERK, JNK, IL-1beta, leukotrienes, arachidonic acid) [14, 15, 16].

1) May Help You Lose Weight

In a clinical trial on 50 formerly obese people, GLA prevented the “yo-yo effect,” or regaining weight after giving up low-calorie diets [17].

GLA promoted a slight weight loss in a clinical trial on 47 people, especially in those with obese parents. However, it failed to do so in another trial on 100 obese women who had unsuccessfully tried other remedies [18+, 19].

GLA might help you lose a few pounds, but don’t expect drastic results.

2) May Improve Skin Conditions

Acne

GLA supplements reduced acne severity in a clinical trial on 45 people with mild acne [20].

It works by blocking the enzyme 5 alpha-reductase, which transforms testosterone into the acne-stimulating dihydrotestosterone (DHT). GLA also inhibits an acne-causing microbe (Propionibacterium acnes) [21, 22, 23].

Eczema

In 11 clinical trials on almost 600 people with eczema, oral GLA restored a healthy fatty acid composition in the skin and reduced inflammation, itching, dryness, and rubbing damage. It also prevented the skin from dehydrating, helping to maintain the integrity and strength of the skin barrier [24+, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34].

However, it was ineffective in 5 trials on almost 600 people with eczema and failed to prevent flare-ups in 2 trials on over 200 children [35, 36, 37, 38, 39, 31, 40].

Even the results of meta-analyses are controversial: two concluded GLA doesn’t work, one found slight benefits for mild eczema, and one noticed the benefits weaken in people who also use steroids [41, 42, 43, 44].

Only 2 studies evaluated topical GLA. In a trial on 32 children, undershirts coated with borage oil reduced redness, itching, and skin dehydration in the back area. Borage oil also improved cradle cap – a type of scalp eczema in babies – and reduced skin dryness in a trial on 62 babies [45, 46].

GLA can soothe, hydrate, and help repair irritated and damaged skin in people with acne and eczema. You can take it orally or apply the oil directly to problematic areas.

3) May Prevent Hair Loss

As previously described, GLA blocks the enzyme that makes DHT, a hormone that is also responsible for male-pattern baldness [21, 47+].

A liposomal lotion with elongated GLA (DGLA) and a compound from soybeans (equol) reduced hair loss in 60 people, more so in women [48].

GLA-containing rice bran extract promoted hair growth in mice. However, this extract is <1% GLA and abounds in other beneficial fatty acids (such as linoleic acid & vitamin E). Another study discovered a special gel (niosomes) that increases the penetration of fatty acids from rice in pig skin [49, 50].

GLA might prevent hair loss, but the evidence so far is limited. It might work best combined with other beneficial fatty acids and vitamins.

4) May Improve Dry Eye

In 3 trials on over 150 people with pink eye, oral GLA (combined with other fatty acids and artificial tears) improved eye dryness and inflammation [51, 52, 53].

It was also effective in 3 trials on 84 people with an autoimmune disease that causes dry eye (Sjögren’s syndrome) [54, 55, 56].

In another trial on 76 women, oral evening primrose oil improved eye dryness from contact lens use [57].

GLA helps reduce eye dryness and inflammation, especially in combination with other fatty acids.

5) May Improve Inflammatory & Autoimmune Conditions

Multiple sclerosis

In a clinical trial on over 100 people with multiple sclerosis, GLA with linoleic acid had no effect on the duration and severity of the attacks. It also failed to prevent disease worsening in another trial on 14 people [58, 59].

In turn, evening primrose and hemp oils, along with a special diet, reduced inflammation and repaired nerve damage in a clinical trial on 100 people with multiple sclerosis [60].

Rheumatoid Arthritis

Borage and black currant oil reduced joint inflammation, pain, and stiffness in 4 trials on almost 150 people with rheumatoid arthritis, but low doses of evening primrose oil were ineffective in 2 trials on 58 people [61, 62, 63, 64, 65, 66].

GLA (from borage and evening primrose oil), fish oil (rich in EPA), and their combination reduced rheumatoid arthritis symptoms, painkiller use, and the risk of heart disease in 4 trials on almost 400 people [67, 68, 69, 70].

A meta-analysis concluded that GLA reduces pain and disability those suffering from rheumatoid arthritis [71].

Asthma

Evening primrose oil increased blood GLA and DGLA but had no effect on asthmatic symptoms in 2 trials on 41 people. In turn, it helped as an add-on to asthma management programs in 3 trials on almost 100 people [72, 73, 74, 75, 76].

GLA reduces inflammation and can offer slight benefits to people with arthritis, asthma, and multiple sclerosis. It’s likely to work best added to other anti-inflammatory interventions.

6) May Improve Diabetic Nerve Damage

In 2 clinical trials on over 100 diabetic people with nerve damage, GLA improved nerve function and reduced the symptoms, especially in those with controlled blood sugar [77, 78].

7) May Prevent Heart Disease

Blood Pressure

GLA combined with EPA and DHA (from fish oil) lowered blood pressure in 2 trials on over 100 people. The same combination prevented high blood pressure during pregnancy (pre-eclampsia) in a trial on 150 women [79, 80].

However, GLA with EPA alone didn’t improve walking distance in those with cut-off leg blood flow and muscle cramps (intermittent claudication) [81].

Clogged Arteries

In 2 small trials on 31 people, GLA lowered blood triglycerides, LDL and total cholesterol, and platelet clumping. It was more effective in people with normal triglycerides or taken for at least 4 months [82, 83].

GLA may help lower blood pressure and blood fats, particularly if you use it with omega-3s from fish oil (EPA and DHA).

8) May Help Fight Cancer

In 3 small trials on 30 people with brain cancer, GLA infused directly into the brain slightly reduced tumor size and increased survival [84, 85, 86].

Oral GLA had no effect on survival or tumor size in a small trial on 15 people with liver cancer, but slightly improved liver function [87].

In a trial on 38 women with breast cancer, oral GLA improved the effectiveness of the anticancer drug tamoxifen [88].

A couple of studies suggest GLA has anti-cancer potential, but we’re far from knowing if it can help people with cancer.

Limitations and Caveats

Most studies didn’t use pure GLA but plant oils also containing other fatty acids. In some studies, these were combined with other oils and special diets.

GLA has been widely investigated for eczema but the results are contradictory, possibly due to the design flaws of some studies, different populations, doses, therapies, and the use of other anti-inflammatory oils – such as olive oil – as placebos.

The benefits of GLA on most other conditions have been studied in only a few trials, some of them with opposing results due to the above-mentioned reasons. In the case of hair loss, there are only studies in mice and cells or testing similar compounds in humans.

Overall, larger, better-designed clinical trials are required to confirm most benefits.

GLA Side Effects & Safety

Side Effects

In clinical trials, up to 2.8 g GLA per day was well tolerated and only caused mild adverse effects such as [62+, 89+]:

  • Headache
  • Belching
  • Bloating
  • Loose stools

One woman taking GLA-rich borage oil developed uncontrollable seizures, while another one using evening primrose oil developed serious lung symptoms (lipoid pneumonia) from inadvertently inhaling the oil [90, 91].

A case report warned that long-term GLA use (over 1 year) could cause inflammation, immunosuppression, and blood clots [92+].

Pregnant women should avoid it due to the lack of safety data. Since GLA passes into breast milk, breastfeeding women should consult their doctor before supplementing [93].

Drug Interactions

GLA reduces blood clotting, as seen in human and animal studies. People on blood thinners such as warfarin should avoid GLA to prevent excessive bleeding [83, 94].

Genetics

Two genes are associated with GLA, FAD1, and FAD2. These make the fatty acid desaturase enzymes that are involved in the conversion of linoleic acid into GLA.

Genetic variations for certain single nucleotide polymorphisms (SNPs) for either one of these genes can lead to less GLA being produced in the body.

GLA Dosage & Supplements

Dosage

The GLA oral doses used in clinical trials were:

  • Weight loss: 890 mg/day [17]
  • Diabetic nerve damage: 360-480 mg/day [77, 78]
  • Autoimmune and inflammatory diseases: 1,400-2,800 mg/day [58, 59+, 61, 62]
  • Dry eyes: 30-50 mg/day [51+, 57+]
  • Eczema: 160-480 mg/day (adults) and 80-320 mg/day (children) [44+]
  • Heart disease: 240-560 mg/day [83+, 80+]

Forms of Supplementation

GLA supplements are available as pure GLA or seed oils from borage, evening primrose, and black currant.

Oral supplements come as softgels or capsules.

Topical GLA forms include:

  • Oils
  • Lotions
  • Creams
  • Shampoos
  • Eyedrops

User Experiences

People take GLA for a variety of reasons: weight loss, rheumatoid arthritis, hair loss, dry eyes, skin health, PMS, and menopausal symptoms. Users were generally satisfied and reported improvements.

Dissatisfied users mostly complained that the supplement didn’t work, most frequently in the case of weight loss. A few noticed upset digestion as a side effect. Some users found the pills were difficult to take, and others couldn’t handle the oil’s unpleasant smell.

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Takeaway

Gamma-linoleic acid or GLA is an omega-6 fatty acid with strong anti-inflammatory benefits. You’ll find it in the seeds of several herbs with a long history of use, such as borage, black currant, and evening primrose. 

GLA may help you get rid of a few extra pounds, but the effect is modest. The best evidence supports its use for skin problems. It can soothe irritated skin and strengthen the damaged skin barrier in people with acne and eczema. GLA might also help with other inflammatory and chronic diseases, but the research is limited. 

Supplements with GLA are generally safe, but they can have a strong odor that puts off most users – especially if you plan to use it on your skin. To bypass this, go with the deodorized pure oil or capsules.

About the Author

Carlos Tello, PhD (Molecular Biology)

PhD (Molecular Biology)

Carlos received his PhD and MS from the Universidad de Sevilla.

Carlos spent 9 years in the laboratory investigating mineral transport in plants. He then started working as a freelancer, mainly in science writing, editing, and consulting. Carlos is passionate about learning the mechanisms behind biological processes and communicating science to both academic and non-academic audiences. He strongly believes that scientific literacy is crucial to maintain a healthy lifestyle and avoid falling for scams.

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