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+].
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
- 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+]:
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+].
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 .
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].
2) May Improve Skin Conditions
GLA supplements reduced acne severity in a clinical trial on 45 people with mild acne .
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].
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].
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].
3) May Prevent Hair Loss
A liposomal lotion with elongated GLA (DGLA) and a compound from soybeans (equol) reduced hair loss in 60 people, more so in women .
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].
4) May Improve Dry Eye
In another trial on 76 women, oral evening primrose oil improved eye dryness from contact lens use .
5) May Improve Inflammatory & Autoimmune Conditions
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 .
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 .
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].
6) May Improve Diabetic Nerve Damage
7) May Prevent Heart Disease
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) .
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].
8) May Help Fight Cancer
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 .
In a trial on 38 women with breast cancer, oral GLA improved the effectiveness of the anticancer drug tamoxifen .
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
- 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 .
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
The GLA oral doses used in clinical trials were:
- Weight loss: 890 mg/day 
- 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:
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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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.