Cold-Pressed Seed Oil
Oil extracted from the seeds by cold pressing, preserving its fatty acid profile.
Cold-Pressed Oil
Onagraceae · North American Native
Biological Overview
Oenothera biennis is a biennial plant native to North America, quite widespread across Mediterranean and Atlantic coastal zones. It has a stem spotted with red, lanceolate leaves arranged along the stem, and yellow flowers with four petals.
HabitBiennial
Native RangeNorth America
Seed Oil ContentUp to 25% of seed weight
GLA Content8–14% of seed oil
Botanical Classification
Taxonomy & Identification
- Latin Name
- Oenothera biennis L.
- Family
- Onagraceae
- Common Names
- Evening Primrose, Onagra
- Parts Used
- Seeds and cold-pressed seed oil
- Flowering Habit
- Yellow flowers, 4 petals, open in evening
- Origin
- North America; naturalized on Mediterranean and Atlantic coasts
Ethnobotany & Traditional Use
History & Tradition
Evening primrose is native to North America and naturalized along the Mediterranean and Atlantic coasts of Europe. Its name reflects the plant's pale yellow flowers, which open only in the evening.
Evening primrose's modern reputation rests almost entirely on 20th-century research into its seed oil, which contains an unusually high proportion of gamma-linolenic acid (GLA) — a relatively rare omega-6 fatty acid that positioned the oil as a subject of extensive clinical research into inflammatory and hormonal conditions.
Clinical interest has focused most heavily on cyclical breast pain and non-hormonal menopause symptom relief, while systematic reviews have found no demonstrated benefit for the plant's once-popular use around labor induction. 6910
⚠ Not the Same as Primrose (Primula)
Despite the similar name, evening primrose (Oenothera biennis) is unrelated to primrose (Primula species) — different families entirely, with different constituents and uses.
The Key Compound
Gamma-Linolenic Acid (GLA) — Deep Dive
The rare omega-6 fatty acid behind evening primrose oil's anti-inflammatory and mammary-supportive reputation.
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A Rare Omega-6 Precursor
GLA makes up 8–14% of the seed oil, alongside linoleic acid (65–80%) and oleic acid (6–11%). 1
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Direct Precursor to PGE1
Gamma-linolenic acid is a direct precursor of prostaglandin E1 (PGE1), a key anti-inflammatory eicosanoid.
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Linoleic Acid's Cholesterol-Lowering Threshold
A diet exceeding 12% of total caloric intake from linoleic acid lowers HDL-cholesterol via LDL cholesterol-ester depletion and inhibition of hepatic apo-B-rich lipoprotein synthesis.
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Favorable Mammary Gland Action
The seed oil shows a notably favorable action on the mammary gland, underlying its use for cyclical breast pain.
⚠ Omega-6:Omega-3 Balance Matters
Context matters more than the isolated supplement alone.
GLA and linoleic acid are both omega-6 fatty acids. An ideal dietary ratio of roughly 1:6 between omega-3 and omega-6 is recommended — evening primrose oil's benefit is best considered within this broader dietary context, not as an isolated supplement.
Pharmaceutical Preparations
Parts Used
The seeds and their cold-pressed oil are used medicinally, prepared as a single documented form.
Clinical Dosimetry
Dosages
No standardized usual dosage has been established for evening primrose oil generally; dosing should be guided by a qualified practitioner.
Phytochemistry
Composition
Seed composition only — no gemmotherapy (bud) or essential-oil fraction is documented for this species; the seed's fixed oil is the plant's primary active preparation.
Seed — Primary Constituents
Fixed OilFatty oil content of the seed
Up to 25%
Gamma-Linolenic AcidOmega-6 fatty acid, the signature marker compound 1
8–14%
Linoleic AcidLeading omega-6 fatty acid in the oil
65–80%
Oleic AcidMonounsaturated fatty acid
6–11%
SterolsStructural plant constituents
Present
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Anti-inflammatory
Attributed to GLA's role as a direct precursor of prostaglandin E1. 2
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Antioxidant
Radical-scavenging activity documented for both the oil and its polyphenol content. 35
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Favorable Mammary Gland Action
A notably favorable effect on the mammary gland, relevant to its use for cyclical breast pain.
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Antitumor (Preliminary)
The seed shows preliminary antitumor properties in a gallic-acid-containing phenolic fraction. 4
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Cyclooxygenase & Elastase Inhibiting
Constituents inhibit cyclooxygenase and neutrophil elastase alongside their radical-scavenging activity. 3
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Cholesterol-Modulating (Dose-Dependent)
High linoleic acid intake (above 12% of total calories) lowers HDL-cholesterol via LDL cholesterol-ester depletion.
Clinical Applications
Clinical Indications
Evening primrose oil's best-studied use is cyclical breast pain, extending to menopause, skin conditions, and joint health.
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Breast & Menstrual Health
Primary Indication
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Menopause
Traditional / Clinical Indication
- Non-Hormonal Symptom Relief: used as a non-hormonal approach to menopausal (climacteric) symptoms. 9
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Skin & Joint Conditions
Traditional / Clinical Indication
- Skin Conditions: eczema, ichthyosis, and psoriasis.
- Rheumatoid Arthritis: studied at 2.8 mg of GLA daily in a randomized, placebo-controlled trial. 13
- Wrinkle Prevention: traditionally used for this purpose.
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Use Considerations
Clinical Precautions
Pharmacodynamics
Mode of Action
Evening primrose oil's effects converge on GLA's role in eicosanoid synthesis, framed within its broader omega-6 dietary context.
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Omega-3:Omega-6 Dietary Balance
An ideal dietary ratio of roughly 1:6 between omega-3 and omega-6 fatty acids should be maintained; evening primrose oil's omega-6 contribution is best considered within this broader balance.
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GLA as a Direct PGE1 Precursor
Gamma-linolenic acid serves as a direct precursor to prostaglandin E1, a key anti-inflammatory eicosanoid.
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Cyclooxygenase & Neutrophil Elastase Inhibition
Constituents in evening primrose oil show radical-scavenging, cyclooxygenase-inhibiting, and neutrophil elastase-inhibiting activity. 3
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Dose-Dependent Lipoprotein Effects
At high dietary intake (above 12% of total calories), linoleic acid lowers HDL-cholesterol via depletion of LDL cholesterol esters and inhibition of hepatic apo-B-rich lipoprotein synthesis.
Risk Profile
Safety & Interactions
Evening primrose oil has a notably clean safety record — no adverse effects are specifically documented, with only general dietary considerations around omega-6 intake.
Adverse Effects
- None Specifically Documented: no adverse effects are documented specifically for evening primrose oil.
- Dose-Dependent Lipid Effect: high intake of linoleic acid (above 12% of total daily calories) can lower HDL-cholesterol — a general dietary consideration rather than a documented supplement-specific adverse effect.
Contraindications & Interactions
- No Documented Contraindications: none are specifically documented for this plant.
- Not Proven for Labor Induction: despite historical use, systematic reviews found no demonstrated benefit for labor induction or cervical ripening in pregnant women. 101112
- Omega-6 Balance: consider alongside overall dietary omega-3 intake given evening primrose oil's exclusively omega-6 fatty acid profile.
Clinical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice. Consult a qualified healthcare provider before starting evening primrose oil, particularly during pregnancy or alongside other supplements affecting hormone levels.
Common Questions
Frequently Asked Questions
What is evening primrose oil used for?
Evening primrose oil is used for mastopathies, cyclical breast pain, and premenstrual syndrome, as a non-hormonal option for menopausal symptoms, for hypercholesterolemia, eczema, ichthyosis, psoriasis, and rheumatoid arthritis, and as a dietary adjunct in multiple sclerosis.
How does evening primrose oil work?
Its gamma-linolenic acid (GLA) serves as a direct precursor to prostaglandin E1, an anti-inflammatory eicosanoid. Constituents in the oil also show radical-scavenging, cyclooxygenase-inhibiting, and neutrophil elastase-inhibiting activity.
What is the typical evening primrose oil dosage?
No standardized usual dosage has been established for evening primrose oil generally. A randomized, placebo-controlled trial for rheumatoid arthritis used 2.8 mg of GLA daily.
Does evening primrose oil help with breast pain (mastalgia)?
Yes, it's one of its best-studied uses. Multiple clinical studies have compared evening primrose oil to other treatments for mastalgia and examined factors affecting its therapeutic efficacy in benign breast disease.
Can evening primrose oil induce labor?
No. Despite historical popularity for this use, systematic reviews and randomized trials have found no demonstrated benefit for oral evening primrose oil in inducing labor or ripening the cervix in pregnant women.
Is evening primrose oil safe?
No adverse effects are specifically documented for evening primrose oil. As a general dietary consideration, high linoleic acid intake above 12 percent of total daily calories can lower HDL-cholesterol.
What is gamma-linolenic acid (GLA)?
GLA is a relatively rare omega-6 fatty acid making up 8 to 14 percent of evening primrose seed oil. It acts as a direct precursor to prostaglandin E1, an anti-inflammatory compound, and underlies most of the oil's studied effects.
Is evening primrose the same as primrose (Primula)?
No. Despite the similar name, evening primrose (Oenothera biennis) is unrelated to primrose (Primula species) — different families entirely, with different constituents and uses.
Sources
Bibliography
↑1. Hudson BJF. Evening primrose (Oenothera spp.) oil and seed. J Am Oil Chem Soc. 1984;61(3):540–543.
↑2. Knorr R, Hamburger M. Quantitative analysis of anti-inflammatory and radical scavenging triterpenoid esters in evening primrose oil. J Agric Food Chem. 2004;52(11):3319–3324.
↑3. Hamburger M, Riese U, Graf H, et al. Constituents in evening primrose oil with radical scavenging, cyclooxygenase, and neutrophil elastase inhibitory activities. J Agric Food Chem. 2002;50(20):5533–5538.
↑4. Dalla Pellegrina C, Padovani G, Mainente F, et al. Anti-tumour potential of a gallic acid-containing phenolic fraction from Oenothera biennis. Cancer Lett. 226(1):17–25.
↑5. Shahidi F, Amarowicz R, He Y, Wettasinghe M. Antioxidant activity of phenolic extracts of evening primrose (Oenothera biennis): a preliminary study. J Food Lipids. 1997;4(2):75–86.
↑6. Adhikary OD, Maulik D, Sarkar A. Comparison of effectiveness among Centchroman, Danazol & Evening primrose oil for the management of mastalgia in benign breast diseases. IOSR J Dental Med Sci. 2018;17:1–5.
↑7. Thakur N, Nazeer N, Wani R, Parray F. Evening primrose oil and vitamin E in mastalgia — which is better. J Med Sci Clin Res. 2016;4(11):13999–14003.
↑8. Balci FL, Uras C, Feldman S. Clinical factors affecting the therapeutic efficacy of evening primrose oil on mastalgia. Ann Surg Oncol. 2020;27(12):4844–4852.
↑9. Albertazzi P. Non-estrogenic approaches for the treatment of climacteric symptoms. Climacteric. 2007;10(Suppl 2):115–120.
↑10. Moradi M, Niazi A, Heydarian Miri H, Lopez V. The effect of evening primrose oil on labor induction and cervical ripening: a systematic review and meta-analysis. Phytother Res. 2021.
DOI: 10.1002/ptr.7147 →
DOI: 10.1002/ptr.7147 →
↑11. Bayles B, Usatine R. Evening primrose oil. Am Fam Physician. 2009;80(12):1405–1408.
PubMed: PMID 20000302 →
PubMed: PMID 20000302 →
↑12. Kalati M, Kashanian M, Jahdi F, Naseri M, Haghani H, Sheikhansari N. Evening primrose oil and labour, is it effective? A randomised clinical trial. J Obstet Gynaecol. 2018;38(4):488–492.
PubMed: PMID 29426270 →
PubMed: PMID 29426270 →
↑13. Zurier RB, Rossetti RG, Jacobson EW, et al. Gamma-linolenic acid treatment of rheumatoid arthritis. A randomized, placebo-controlled trial. Arthritis Rheum. 1996;39(11):1808–1817.
PubMed: PMID 8912502 →
PubMed: PMID 8912502 →
Additional Sources
Mukherjee KD, Kiewitt I. Formation of gamma-linolenic acid in the higher plant evening primrose (Oenothera biennis L.). J Agric Food Chem. 1987;35(6):1009–1012.
Wettasinghe M, Shahidi F, Amarowicz R. Identification and quantification of low molecular weight phenolic antioxidants in seeds of evening primrose (Oenothera biennis L.). J Agric Food Chem. 2002;50(5):1267–1271.