Seed oil with the highest gamma-linolenic acid content of any commercial source, typically 20–24% GLA. GLA is an omega-6 fatty acid one step past linoleic acid.
The appeal of GLA is that it can be elongated to dihomo-gamma-linolenic acid, the precursor to the anti-inflammatory 1-series prostaglandins, which is an unusual thing for an omega-6 to do. Trials in rheumatoid arthritis at 1.4–2.8 g GLA/day reported reduced tender joint counts and less non-steroidal anti-inflammatory drug use, and a Cochrane review judged that evidence potentially useful but low quality. The eczema literature, which is where borage oil is most sold, is clearly negative: a Cochrane review of oral evening primrose and borage oil found no benefit for eczema and recommended no further trials.
Sold as
Softgel, Liquid oil
Standardised to
Usually 20–24% GLA; dose should be read as mg GLA rather than mg oil — a product without this marker may not resemble what was studied.
Regulation: Sold as a dietary supplement with no pre-market efficacy or safety review. Borage plant material contains pyrrolizidine alkaloids and only oil certified as alkaloid-free should be used internally; several European regulators set limits on pyrrolizidine alkaloid content in supplements.
What the research used
The amounts, forms and durations published trials of Borage oil (GLA) actually administered.
These are the amounts published trials administered — not a recommendation, and not a dose to copy. Trial participants were screened, supervised and given a characterised preparation. What is in a retail bottle is frequently not what was studied, and the amount that suits one person is not general advice.
Studied for Rheumatoid arthritis
1.4–2.8 g
Limited
GLA daily, roughly 6–14 g of borage oil · 6–12 months
Reaching these GLA doses takes far more oil than a typical 1,000 mg capsule supplies — often ten or more capsules a day. Trials are small and a Cochrane review rated the evidence low quality.
Studied for Atopic dermatitis
0.3–0.9 g
Not enough
GLA daily · 12–24 weeks
Recorded because it is what trials used, not because it worked. Pooled analysis found oral GLA oils no better than placebo for eczema symptoms.
This is general information about food, not medical advice. It cannot diagnose, treat or replace guidance from a clinician who knows your history.
When it was taken
Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.
None of the timings below were directly compared in a trial. They reflect how the research happened to dose, or what the pharmacology implies — which is not the same as a timing being better.
🍽️With food
Not enough
Taken with food for absorption and tolerability, as with any oil. No timing comparison has been run.
Timing was not directly compared. This reflects convention or how the compound behaves in the body, not a trial showing this window works better.
The evidence in depth
Best supported: Not enough
What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how promising the supplement sounds. How we rate evidence.
Trials of high-dose GLA in rheumatoid arthritis report reductions in tender and swollen joint counts and in painkiller use over six months or more. The trials are few, small and mostly decades old, and a systematic review rated the evidence low quality.
What may be going on: GLA is elongated to dihomo-gamma-linolenic acid, which competes with arachidonic acid and yields the less inflammatory 1-series prostaglandins.
Not enough evidence. Not enough human research to say anything useful yet.
No source is attached to this association yet, so it is rated not enough evidenceby default. It is listed because people commonly ask about it — not because there is evidence for it.
A Cochrane review of oral borage and evening primrose oil for eczema concluded they were no more effective than placebo, and that further trials of this question were not warranted. This is one of the clearer negative findings in the supplement literature.
Not enough evidence. Not enough human research to say anything useful yet.
Systematic review · BMC complementary medicine and therapies · 2024 · PMID 38360611
Deep research mode adds each paper’s own conclusion and stated limitations.
Things to know
Interactions, contraindications and dose limits, most serious first. Concentrated extracts interact with medication in ways the whole plant does not, so this section carries more weight here than it does on a food page.
Worth knowing
Pyrrolizidine alkaloids and liver toxicity
Borage plant material contains hepatotoxic pyrrolizidine alkaloids. Refined seed oil sold as alkaloid-free should not, but the assurance depends on the manufacturer, and unrefined or home-prepared borage preparations are a genuine liver risk.
Case reports link GLA-rich oils to seizures, particularly alongside phenothiazine antipsychotics or in people with existing epilepsy. The mechanism is not established but the caution is standard.
Interaction
Bleeding risk and antiplatelet effects
Interacts withWarfarin, direct oral anticoagulants, aspirin, clopidogrel
GLA-rich oils have been reported to inhibit platelet aggregation, and additive effects with anticoagulant and antiplatelet drugs are plausible. Stopping before surgery is the usual advice.
Worth knowing
Pregnancy
Borage has traditional use as a uterine stimulant and the pyrrolizidine alkaloid issue is more consequential in pregnancy. It is generally avoided during pregnancy and breastfeeding.
In the food catalogue
The whole-food form, where one exists. The evidence for a concentrated extract rarely transfers to the food, or the other way round — these are cross-links, not equivalents.