Gamma-linoleic acid

1. What conditions has Gamma-linoleic acid been studied for?

• Acne vulgaris: Studied as a dietary supplement (e.g., borage oil providing 400 mg/day GLA) in a randomized controlled dietary intervention trial; also discussed in a broader diet-and-acne review.

• Dry eye disease (DED): Studied as part of a combined essential fatty acid supplement (EPA + DHA + GLA) in a randomized, double-masked, placebo-controlled trial.

• Cardiovascular-related endpoints in generally healthy adults: Studied as part of a multi-ingredient supplement (curcumin + EPA + astaxanthin + GLA; “CEAG”) assessing blood pressure and inflammatory/endothelial markers.

• Women’s health conditions via evening primrose oil (EPO, contains GLA): A review summarizes clinical studies in PMS, hot flashes, mastalgia, fibroadenomas, gestational diabetes, cervical ripening/dilation (note: this is EPO as a mixture; effects cannot be attributed to GLA alone from this study).

• Metabolic syndrome (MetS) risk biology: Not supplementation, but observational work linking fatty acid profiles and estimated desaturase activity (including Δ6-desaturase, which produces GLA from linoleic acid) with MetS prevalence and risk factors.

2. Does it work in treating those conditions? Summarize the evidence.

• Acne vulgaris: Some evidence of benefit (small RCT).

  • A 10-week randomized controlled parallel dietary intervention (n=45) compared omega-3s, GLA (borage oil, 400 mg GLA), and control. After 10 weeks, the GLA group had significant decreases in inflammatory and non-inflammatory lesion counts, with similar subjective improvement.

  • Histology showed reduced inflammation and reduced immunohistochemical staining intensity for interleukin-8 in acne lesions after omega-3 or GLA supplementation.

  • Limitations from the study: small sample size, short duration, and it is one trial; replication and longer-term outcomes are not established here.

• Dry eye disease: Symptom improvement in a subgroup; signs did not change.

  • In a 3-month prospective randomized double-masked study (n=50 completers), a supplement containing EPA 1200 mg + DHA 300 mg + GLA 150 mg improved symptoms (OSDI) in very symptomatic participants (baseline OSDI ≥52): -20.8 points at 3 months (within-group change reported; abstract notes clinically meaningful improvement in this subgroup).

  • However, objective ocular assessments (tear breakup time, osmolarity, staining, Schirmer, etc.) showed no significant changes at 1 or 3 months.

  • Attribution limitation: because GLA was combined with omega-3s, the study does not isolate GLA’s independent effect.

• Blood pressure/inflammation/endothelial function: Evidence is confounded by combination therapy.

  • A 4-week randomized double-blind placebo-controlled trial of a multi-ingredient supplement including GLA (plus curcumin, EPA, astaxanthin) reported a significant reduction in systolic blood pressure versus placebo (mean reduction ~4.7 mmHg; p=0.002).

  • Attribution limitation: the study does not allow conclusions about GLA alone because multiple active ingredients were used.

• Women’s health conditions (EPO): mixed/uncertain specificity to GLA.

  • A narrative-style review states studies “confirmed” efficacy of evening primrose oil for women’s health issues (with emphasis on mastalgia and PMS) and suggests effects may require 4–6 months of regular use.

  • Limitation: this is not a single controlled trial in the study, and EPO contains mostly linoleic acid plus GLA; the study does not quantify effect sizes or study quality.

3. What health benefits does it have?

• Potential anti-inflammatory effects in skin (acne context):

  • In the acne RCT, GLA supplementation was associated with reduced inflammatory lesions and histologic evidence of reduced inflammation, including reduced IL-8 staining intensity in lesions.

• Symptom relief in dry eye (when combined with omega-3s):

  • In moderate-to-severe DED, the EPA/DHA/GLA combination produced a clinically meaningful symptom improvement in extremely symptomatic participants (OSDI ≥52), though objective signs did not improve.

• Possible cardiovascular benefit signals (in combination):

  • The CEAG combination trial reported a reduction in systolic blood pressure over 4 weeks versus placebo, but the specific contribution of GLA is unknown.

• Dietary pattern relevance in acne:

  • A diet-and-acne review notes studies where increased intake of omega-3 fatty acids and GLA (e.g., fish and healthy oils) was associated with acne benefit, supporting GLA as a candidate adjunct within broader dietary approaches.

4. Does it have any downsides or side effects?

• In the acne RCT (borage oil providing 400 mg/day GLA for 10 weeks), no severe adverse effects were reported. This supports short-term tolerability in that small study, but does not rule out rarer or longer-term adverse effects.

• Allergy risk depends on the source product, not necessarily GLA itself. A case report described anaphylaxis after Spirulina ingestion; Spirulina is noted to contain GLA among other nutrients. Testing implicated Spirulina algae as the allergen. This highlights that “GLA-containing supplements” can carry ingredient-specific allergy risks (e.g., algae), even if GLA is not the allergen.

• Metabolic risk context (not a side effect of supplementation, but relevant biology): In an observational study, higher estimated Δ6-desaturase activity (the enzyme that converts linoleic acid to GLA) was associated with higher prevalence of metabolic syndrome and adverse metabolic risk profiles. This does not prove GLA supplementation causes harm, but suggests fatty-acid metabolism patterns involving the GLA pathway may track with metabolic risk in some populations.

5. Is it beneficial or harmful for any genetic variations (pharmacogenomics)?

• FADS gene cluster variants influence desaturase activity that affects GLA-related pathways. In young Canadian adults of Caucasian and Asian descent, multiple SNPs in FADS1/FADS2 were associated with estimated desaturase activities using fatty-acid ratios, including GLA:LA (a proxy for Δ6-desaturase-related conversion along the n-6 pathway).

• Key finding: The FADS1 rs174547 SNP showed the strongest association with a desaturase activity proxy (AA:LA) in both ethnic groups; carriers of the C allele had lower desaturase activity than carriers of the T allele in both groups (minor allele differed by ethnicity).

• What this means for GLA supplementation: These data suggest people with certain FADS variants may differ in their ability to convert dietary linoleic acid into downstream long-chain fatty acids. However, the study does not test clinical responses to GLA supplementation by genotype, so it cannot conclude that any variant makes GLA supplementation definitively beneficial or harmful—only that fatty-acid metabolism differs by genotype, which could plausibly modify response.

References

1. Effects of Diet on Acne and Its Response to Treatment.
   Hilary Baldwin, Jerry Tan (2021) - American journal of clinical dermatology
2. Plasma fatty acid composition, estimated desaturase activities, and their relation with the metabolic syndrome in a population at high risk of cardiovascular disease.
   Jordi Mayneris-Perxachs, Marcela Guerendiain, Ana I Castellote, Ramón Estruch, María Isabel Covas, Montserrat Fitó, Jordi Salas-Salvadó, Miguel A Martínez-González, Fernando Aros, Rosa M Lamuela-Raventós, M Carmen López-Sabater (2014) - Clinical nutrition (Edinburgh, Scotland)
3. Polymorphisms in FADS1 and FADS2 alter desaturase activity in young Caucasian and Asian adults.
   Diana M Merino, Holly Johnston, Shannon Clarke, Kaitlin Roke, Daiva Nielsen, Alaa Badawi, Ahmed El-Sohemy, David W L Ma, David M Mutch (2011) - Molecular genetics and metabolism
4. Effect of dietary supplementation with omega-3 fatty acid and gamma-linolenic acid on acne vulgaris: a randomised, double-blind, controlled trial.
   Jae Yoon Jung, Hyuck Hoon Kwon, Jong Soo Hong, Ji Young Yoon, Mi Sun Park, Mi Young Jang, Dae Hun Suh (2014) - Acta dermato-venereologica
5. Evening Primrose (Oenothera biennis) Oil in Management of Female Ailments
   Mohaddese Mahboubi (2019)
6. Metabolic Engineering Strategies for Improved Lipid Production and Cellular Physiological Responses in Yeast
   Wei Jiang, Chao Li, Yanjun Li, Huadong Peng (2022) - Journal of fungi (Basel, Switzerland)
7. Effect of a Novel Omega-3 and Omega-6 Fatty Acid Supplement on Dry Eye Disease: A 3-month Randomized Controlled Trial.
   Alison Ng, Jill Woods, Theresa Jahn, Lyndon W Jones, Jenna Sullivan Ritter (2022) - Optometry and vision science : official publication of the American Academy of Optometry
8. Metabolic engineering of soybean seeds for enhanced vitamin E tocochromanol content and effects on oil antioxidant properties in polyunsaturated fatty acid-rich germplasm.
   Anji Reddy Konda, Tara J Nazarenus, Hanh Nguyen, Junsi Yang, Malleswari Gelli, Samantha Swenson, Jamie M Shipp, Monica A Schmidt, Rebecca E Cahoon, Ozan N Ciftci, Chunyu Zhang, Tom Elmo Clemente, Edgar B Cahoon (2020) - Metabolic engineering
9. Anaphylaxis to Spirulina confirmed by skin prick test with ingredients of Spirulina tablets.
   Thuy-My Le, André C Knulst, Heike Röckmann (2014) - Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association
10. A combined effect of Cavacurcumin, Eicosapentaenoic acid (Omega-3s), Astaxanthin and Gamma -linoleic acid (Omega-6) (CEAG) in healthy volunteers- a randomized, double-blind, placebo-controlled study.
    Divya Birudaraju, Lavanya Cherukuri, April Kinninger, Bhanu T Chaganti, Kashif Shaikh, Sajad Hamal, Ferdinand Flores, Sion K Roy, Matthew J Budoff (2020) - Clinical nutrition ESPEN
11. Dioxins levels in human blood after implementation of measures against dioxin exposure in Japan.
    Basilua Andre Muzembo, Miyuki Iwai-Shimada, Tomohiko Isobe, Kokichi Arisawa, Masayuki Shima, Tetsuhito Fukushima, Shoji F Nakayama (2019) - Environmental health and preventive medicine
12. Fatty Acids and Eicosanoids Change during High-Fiber Diet in NAFLD Patients-Randomized Control Trials (RCT).
    Dominika Maciejewska-Markiewicz, Arleta Drozd, Joanna Palma, Karina Ryterska, Viktoria Hawryłkowicz, Patrycja Załęska, Ewa Wunsh, Katarzyna Kozłowska-Petriczko, Ewa Stachowska (2022) - Nutrients
13. The C18:3n6/C22:4n6 ratio is a good lipid marker of chronic kidney disease (CKD) progression.
    Małgorzata Szczuko, Małgorzata Kaczkan, Sylwia Małgorzewicz, Przemysław Rutkowski, Alicja Dębska-Ślizień, Ewa Stachowska (2020) - Lipids in health and disease
14. Associations of Maternal Polyunsaturated Fatty Acids With Telomere Length in the Cord Blood and Placenta in Chinese Population.
    Xuanyi Liu, Qiaoyu Shi, Xiuqin Fan, Hang Chen, Na Chen, Yurong Zhao, Kemin Qi (2021) - Frontiers in nutrition
15. Free radical derivatives formed from cyclooxygenase-catalyzed dihomo-γ-linolenic acid peroxidation can attenuate colon cancer cell growth and enhance 5-fluorouracil's cytotoxicity.
    Yi Xu, Jin Qi, Xiaoyu Yang, Erxi Wu, Steven Y Qian (2014) - Redox biology
16. Omega-3 fatty acids induce Ca(2+) mobilization responses in human colon epithelial cell lines endogenously expressing FFA4.
    Jung-min Kim, Kyoung-pil Lee, Soo-jin Park, Saeromi Kang, Jin Huang, Jung-min Lee, Koichi Sato, Hae-young Chung, Fumikazu Okajima, Dong-soon Im (2015) - Acta pharmacologica Sinica
17. Fatty Acid Levels and Their Inflammatory Metabolites Are Associated with the Nondipping Status and Risk of Obstructive Sleep Apnea Syndrome in Stroke Patients.
    Arleta Drozd, Dariusz Kotlęga, Przemysław Nowacki, Sylwester Ciećwież, Tomasz Trochanowski, Małgorzata Szczuko (2022) - Biomedicines
18. Nutritionally Important Pro-Health Active Ingredients and Antioxidant Properties of Fruits and Fruit Juice of Selected Biennial Fruiting
    Mirosława Chwil, Renata Matraszek-Gawron, Mikołaj Kostryco, Monika Różańska-Boczula (2023) - Pharmaceuticals (Basel, Switzerland)

This article summarizes published research for educational purposes. It is not medical advice. Talk to your doctor before starting, stopping, or changing any supplement or medication.