Omega-6 polyunsaturated fatty acids (linoleic acid and GLA)

Essential polyunsaturated fatty acids

ATC code: A11JA (Other vitamins, minerals, and nutraceuticals (local hierarchy))

Mechanism of action

Linoleic acid is an essential omega-6 PUFA, a precursor of arachidonic acid and series-2 eicosanoids: prostaglandins E2, thromboxanes, and leukotrienes. Gamma-linolenic acid (GLA) from borage and evening primrose oil bypasses the delta-6 desaturase bottleneck and converts to dihomo-gamma-linolenic acid – the source of the anti-inflammatory prostaglandin E1. set an adequate intake for linoleic acid at 4 % of daily energy (about 10 g for an adult).

Indications

Rheumatoid arthritis

Adjunct

Gamma-linolenic acid (GLA) from borage or evening primrose oil at 1.4–2.8 g/day delivered modest reductions in pain and morning stiffness in small randomised trials in rheumatoid arthritis. The Cochrane review CD002948 (2011) rated the effect as weak, inconsistent, and insufficient to replace disease-modifying therapy. Current 2023 and SER 2024 guidelines build treatment on methotrexate, biologics, and targeted JAK inhibitors. GLA can be considered as an adjunct to mainstay therapy after agreement with a rheumatologist, never as a substitute.

Sources

Cochrane: Herbal therapy for treating rheumatoid arthritis (2011)

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

Cardiovascular prevention through supplements

Not recommended

Omega-6 is sold as part of "omega 3-6-9" complexes on the idea of "balanced fats for the heart." The reality is different: nearly everyone gets linoleic acid in excess from sunflower, corn, and soybean oil, and adults on a standard diet do not develop deficiency. The 2017 Presidential Advisory and the 2010 Opinion both recommend meeting linoleic acid needs through food, not capsules. If the goal is cardiovascular protection, omega-3 (EPA+DHA) and the Mediterranean diet do the work – not omega-3-6-9 combinations. Buying these supplements means less EPA+DHA per capsule at a higher price than pure omega-3. If a clinician proposes such a supplement for cardiovascular prevention, consider seeking a second opinion.

Sources

Severe atopic dermatitis

Not recommended

Evening primrose oil and borage oil – the main sources of gamma-linolenic acid – have been marketed for decades to treat atopic dermatitis. The Cochrane review CD004416 pooled 27 randomised trials and concluded that oral GLA oils do not reduce itch or improve atopic dermatitis severity compared with placebo. The UK regulator MHRA withdrew evening primrose oil licences back in 2002 precisely because of the lack of efficacy evidence. If evening primrose or borage oil was prescribed for atopic dermatitis, consider seeking a second opinion – effective options exist (topical calcineurin inhibitors, dupilumab, JAK inhibitors).

Sources

Cochrane: Oral evening primrose oil and borage oil for eczema (2013)

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Safety

Contraindications

Allergy to a component (fish, nuts, soy, the source plant oil)
Active bleeding or history of haemorrhagic stroke
Epilepsy (high-dose GLA may lower the seizure threshold)

Common adverse effects

Belching with an oily aftertaste, mild loose stool
Headache at the start of supplementation

PregnancyFDA N

On a usual diet, pregnant women get enough linoleic acid from vegetable oils and nuts. Standalone high-dose gamma-linolenic acid (GLA) supplements were not studied in pregnancy, so AEMPS and Cochrane advise against borage and evening primrose oil unless prescribed.

Breastfeeding

Linoleic acid reaches breast milk through the maternal diet and is required for the infant's neural development. A nursing mother on a usual diet does not need standalone omega-6 capsules; borage and evening primrose oils should not be taken without medical advice.

Calculate RID

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Frequently asked

What is Omega-6 polyunsaturated fatty acids (linoleic acid and GLA) used for?

Omega-6 polyunsaturated fatty acids (linoleic acid and GLA) is evaluated for the following indications with varying evidence strength: Rheumatoid arthritis (evidence tier C), Cardiovascular prevention through supplements (evidence tier D), Severe atopic dermatitis (evidence tier D). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Omega-6 polyunsaturated fatty acids (linoleic acid and GLA)?

Common side effects of Omega-6 polyunsaturated fatty acids (linoleic acid and GLA) (≥ 1 in 100): Belching with an oily aftertaste, mild loose stool, Headache at the start of supplementation. See the Safety section for uncommon and serious reactions.

Is Omega-6 polyunsaturated fatty acids (linoleic acid and GLA) safe during pregnancy?

FDA category N. On a usual diet, pregnant women get enough linoleic acid from vegetable oils and nuts. Standalone high-dose gamma-linolenic acid (GLA) supplements were not studied in pregnancy, so AEMPS and Cochrane advise against borage and evening primrose oil unless prescribed.

Is Omega-6 polyunsaturated fatty acids (linoleic acid and GLA) compatible with breastfeeding?

Who should not take Omega-6 polyunsaturated fatty acids (linoleic acid and GLA)?

Omega-6 polyunsaturated fatty acids (linoleic acid and GLA) is contraindicated in: Allergy to a component (fish, nuts, soy, the source plant oil); Active bleeding or history of haemorrhagic stroke; Epilepsy (high-dose GLA may lower the seizure threshold). Full list in the Safety section.

Mechanism of action

Indications

Rheumatoid arthritis

Adjunct

Sources

Cochrane: Herbal therapy for treating rheumatoid arthritis (2011)

Safety

Contraindications

Allergy to a component (fish, nuts, soy, the source plant oil)
Active bleeding or history of haemorrhagic stroke
Epilepsy (high-dose GLA may lower the seizure threshold)

Common adverse effects

Belching with an oily aftertaste, mild loose stool
Headache at the start of supplementation

PregnancyFDA N

Breastfeeding

Calculate RID

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Frequently asked

What is Omega-6 polyunsaturated fatty acids (linoleic acid and GLA) used for?

What are the side effects of Omega-6 polyunsaturated fatty acids (linoleic acid and GLA)?

Is Omega-6 polyunsaturated fatty acids (linoleic acid and GLA) safe during pregnancy?

Is Omega-6 polyunsaturated fatty acids (linoleic acid and GLA) compatible with breastfeeding?

Who should not take Omega-6 polyunsaturated fatty acids (linoleic acid and GLA)?