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
The body makes GLA from linoleic acid taken 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+]:
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 may have 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
The body takes the linoleic acid obtained 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].
Possibly Effective for:
1) 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 [17, 18, 19].
A similar treatment also including oral GLA was effective in 3 trials on 84 people with an autoimmune disease that causes dry eye (Sjögren’s syndrome) [20, 21, 22].
In another trial on 76 women, oral evening primrose oil improved eye dryness from contact lens use [23].
While promising, the evidence to claim that GLA helps with dry eye is still limited. These results should be replicated in larger, more robust clinical trials.
2) 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 [24, 25, 26, 27, 28, 29].
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 [30, 31, 32, 33].
A meta-analysis concluded that GLA may reduce pain and disability in people suffering from rheumatoid arthritis [34].
Again, the evidence to support the use of GLA in people with rheumatoid arthritis is promising but limited and includes a few studies with mixed results. Additional clinical research is required.
Insufficient Evidence for:
1) 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 [35, 36].
The results are promising but insufficient to back this health benefit. More clinical trials on larger populations are needed to confirm them.
2) Weight Loss
In a clinical trial on 50 formerly obese people, GLA prevented the “yo-yo effect,” or regaining weight after giving up low-calorie diets [37].
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 [38+, 39].
Taken together, the evidence supporting the role of GLA in weight loss is insufficient. Further clinical research is required.
3) Skin Conditions
Acne
GLA supplements reduced acne severity in a clinical trial on 45 people with mild acne [40].
It probably worked by blocking the enzyme 5 alpha-reductase, which transforms testosterone into the acne-stimulating dihydrotestosterone (DHT). GLA also inhibited an acne-causing microbe (Propionibacterium acnes) [41, 42, 43].
The evidence to claim that GLA improves acne is insufficient. More clinical trials are needed.
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 [44+, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54].
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 [55, 56, 57, 58, 59, 51, 60].
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 [61, 62, 63, 64].
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 [65, 66].
Because the results are mixed, we cannot conclude for certain that GLA helps with eczema. More robust research is needed.
4) 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 [67, 68].
However, GLA with EPA alone didn’t improve walking distance in those with cut-off leg blood flow and muscle cramps (intermittent claudication) [69].
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 [70, 71].
To sum up, very limited evidence suggests that GLA may help lower blood pressure and prevent clogged arteries. Further clinical research is needed to confirm this potential health benefit.
5) Asthma
Evening primrose oil increased blood GLA and DGLA but had no effect on asthmatic symptoms in 2 trials on 41 people. In contrast, it helped as an add-on to asthma management programs in 3 trials on almost 100 people [72, 73, 74, 75, 76].
The existing evidence suggests that GLA may help only in combination with conventional therapies for asthma, but more clinical trials are needed.
6) Cancer
In 3 small trials on 30 people with brain cancer, GLA infused directly into the brain slightly reduced tumor size and increased survival [77, 78, 79].
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 [80].
In a trial on 38 women with breast cancer, oral GLA improved the effectiveness of the anticancer drug tamoxifen [81].
Larger, more robust clinical trials are needed before we can conclude for certain that GLA has any value in anticancer therapy.
Lack of Evidence for:
Hair Loss
As previously described, GLA blocks the enzyme that makes DHT, a hormone that is also responsible for male-pattern baldness [41, 82+].
A liposomal lotion with elongated GLA (DGLA) and a compound from soybeans (equol) reduced hair loss in 60 people, more so in women [83].
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 [84, 85].
Because the studies tested formulations mainly containing other fatty acids, there is no evidence to support the benefits of GLA in preventing hair loss.
Possibly Ineffective for:
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 [86, 87].
In contrast, 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 [88].
Taken together, GLA is possibly ineffective to improve multiple sclerosis or prevent its worsening.
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 [25+, 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 [71, 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
Because GLA is not approved for any conditions, there is no official dose. Users and supplement manufacturers have established unofficial doses based on their experience.
The GLA oral doses used in clinical trials were:
- Weight loss: 890 mg/day [37]
- Diabetic nerve damage: 360-480 mg/day [35, 36]
- Autoimmune and inflammatory diseases: 1,400-2,800 mg/day [86, 87+, 24, 25]
- Dry eyes: 30-50 mg/day [17+, 23+]
- Eczema: 160-480 mg/day (adults) and 80-320 mg/day (children) [64+]
- Heart disease: 240-560 mg/day [71+, 68+]
Forms of Supplementation
GLA supplements are available as pure GLA or seed oils from borage, evening primrose, and black currant. However, they are not approved by the FDA for any conditions due to the lack of solid clinical research. Regulations set manufacturing standards for supplements but don’t guarantee that they are safe or effective. Talk to your doctor before using GLA supplements for any conditions to avoid unexpected interactions.
Oral supplements come as softgels or capsules.
Topical GLA forms include:
- Oils
- Lotions
- Creams
- Shampoos
- Eyedrops
User Experiences
The opinions expressed in this section are solely those of GLA users who may or may not have medical or scientific training. Their reviews do not represent the opinions of SelfHacked. SelfHacked does not endorse any specific product, service, or treatment.
Do not consider user experiences as medical advice. Never delay or disregard seeking professional medical advice from your doctor or other qualified healthcare providers because of something you have read on SelfHacked. We understand that reading individual, real-life experiences can be a helpful resource, but it is never a substitute for professional medical advice, diagnosis, or treatment from a qualified healthcare provider.
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.
Takeaway
Gamma-linoleic acid or GLA is an omega-6 fatty acid with potential 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. Promising but insufficient evidence supports its use for skin problems. It may 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.
