Borage (Borago officinalis L.): A Comprehensive Reference
1. Identity, Botanical Classification, and Forms
1.1 Nomenclature and Taxonomy
Borage (Borago officinalis), also known as starflower, is an annual herb in the flowering plant family Boraginaceae, native to the Mediterranean region. Other common names recorded in the literature include common borage, bee flower, bee plant, and talewort. The plant's family name reflects its place within the borage family (Boraginaceae). B. officinalis has 2n = 2x = 16 chromosomes.
The word "borage" has two competing etymologies in the historical literature. The name "borage" derives from the medieval Latin burra, meaning rough-coated, which refers to the plant's hairs. An alternative explanation suggests it is a corruption of the Latin corago (courage), as in Gerard's rhyme ego borago gaudia semper ago ("I, borage, bring always courage"), in line with its reputation as an herb to dispel melancholy.
1.2 Botanical Description
B. officinalis grows to a height of 60 centimetres (2 feet), and is bristly or hairy all over the stems and leaves; the leaves are alternate, simple, and 5–15 cm long. The flowers are complete, perfect with five narrow, triangular-pointed petals. It features large rough oblong leaves that have a cool cucumber-like aroma and taste. The flowers are borne on red stalks and have five bright yellow stamens that form a cone.
1.3 Geographic Range and Cultivation
The native range of borage includes Northern Africa, the Asia-Temperate region, and Europe. Borage is a naturalised annual plant which has grown wild or in gardens for many centuries. Commercially, borage is grown as an annual herbaceous plant in North America. Traditionally this plant was cultivated for culinary and medicinal uses, although today commercial cultivation is mainly as an oilseed which contains gamma-linolenic acid (GLA) and other fatty acids.
1.4 Plant Parts Used and Common Preparations
The whole plant of borage — stem, leaves, flowers, and seeds — is a source of essential fatty acids (EFAs), but their quality and amount available in the seed oil are richer. Each part of the plant is associated with distinct applications:
- Seed oil (borage seed oil / starflower oil): Cold-pressed or solvent-extracted from the seeds; supplied as soft-gel capsules or liquid oil; the primary commercial supplement form.
- Dried herb (leaves and flowers): Available as plant parts such as the leaf and flower. Used in teas, infusions, and topical preparations.
- Fresh plant: Borage is used as either a fresh vegetable or a dried herb; as fresh borage has a cucumber-like taste, it is often used in salads or as a garnish.
- Culinary use of flowers: The flower has a sweet, honey-like taste and may be used to decorate desserts and cocktails, and is sometimes frozen inside ice cubes.
Vegetable use of borage is common in Germany, in the Spanish regions of Aragón and Navarre, on the Greek island of Crete, and in the northern Italian region of Liguria. In Persian cuisine, borage tea using the dried flowers is called gol gâvzabân ("cow's-tongue-flower").
2. Traditional and Historical Uses
2.1 Antiquity and the Greco-Roman World
Borage is a native annual plant in the Mediterranean region that has been used since ancient times for culinary and medicinal purposes, for the treatment of swelling and inflammation, respiratory complaints and melancholy — epitomised by the old verse Ego borago gaudia semper ago ("I, Borage, bring always courage").
Borage leaves have been used as a potherb and in European herbal medicine since the Middle Ages, and are mentioned by Pliny, Dioscorides, and Galen. Greek physicians like Dioscorides mentioned borage as "brathium," recommending it to "gladden the heart and lift the spirits." Many ancient Romans used borage leaves in wine, believing it promoted courage and dissipated melancholy. Pliny the Elder believed it to be anti-depressant, and it has long been thought to give courage and comfort to the heart.
Already in antiquity, borage did not appear in the most ancient writings of the Greek scientific and medical corpus; it cannot be traced in the collection of writings transmitted under the name of Hippocrates (460–between 375 and 350 BCE), and neither in the founding treatises of botany by Theophrastus.
2.2 Medieval Europe
Indications recorded in medieval literature are numerous: against choleric conditions (bilious conditions), humours (secretions) in the lungs (that is, expectorant), sciatica, hangover, and quartan fever, in addition to inducing joyfulness according to the ancient tradition.
In European traditional medicine, the heart was believed to store the vital spirit and circulate it around the body via the arteries; thus heart medicines were usually medicines for the spirit — for depression and confusion. Borage was much favoured to protect the heart from excess heat in high fevers.
The 12th–15th century English herbal text Agnus castus described borage thus: "This herb grows in gardens, it has a sharp leaf and a blue flower. The property of this plant is that it cleans the red spot in the face. Also, this herb mixed in wine will make men happy and cheerful. It is also good in potage as it is wholesome for the body. This plant is warm and humid."
2.3 Persian and Unani Medicine
In Persian cuisine and medicine, borage tea using the dried purple flowers is called gol gâvzabân. In traditional Unani medicine as practised in parts of India, the leaves were used topically to soothe swellings and furuncles.
2.4 Traditional Preparations and Applications
Traditionally, Borago officinalis has been used to treat hyperactive gastrointestinal, respiratory and cardiovascular disorders, such as gastrointestinal conditions (colic, cramps, diarrhoea), airways conditions (asthma, bronchitis), cardiovascular conditions (cardiotonic, antihypertensive, and blood purifier), and urinary conditions (diuretic and kidney/bladder disorders).
Health properties such as anti-obesity, diuretic, emollient, lenitive, laxative, anti-anaemic, menstrual analgesic, and antipyretic properties are also recorded in the traditional literature.
Borage leaves have been used for rheumatism, colds, and bronchitis, as well as to increase lactation in women; infusions of the leaves were used to induce sweating and diuresis.
Before the invention of ice, borage was used in a cooling drink called a "cool tankard" or "claret cup" consisting of wine, water, lemon, sugar, and borage leaves and flowers.
Borage's popularity as a medicinal herb waned by the early 1900s but revived in the mid-20th century when scientists discovered its GLA-rich seed oil.
3. Chemical Constituents and Active Compounds
3.1 Seed Oil Fatty Acid Profile
Borage oil is the richest plant source of gamma-linolenic acid (GLA), an essential and unusual fatty acid. Borage seeds contain about 30–40% oil, of which GLA constitutes approximately 20–30%. The amount of GLA present in borage is around twice that of evening primrose oil.
A detailed fatty acid profile of borage seed oil shows: not less than 22% C18:3 gamma-linolenic acid (GLA), between 9 and 12% C16:0 palmitic acid, between 3 and 5% C18:0 stearic acid, between 15 and 20% C18:1 oleic acid, between 35 and 42% C18:2 linoleic acid, between 3 and 5% C20:1 eicosenoic acid, and between 1 and 4% C22:1 docosenoic acid.
The seeds of borage contain approximately 38% oil with a GLA content of 20–25%. The oil is made up of 95.7% neutral lipids, 2.0% glycolipids, and 2.3% phospholipids.
Tocopherols (vitamin E) are also natural effective antioxidants, and borage species contain high amounts of δ-tocopherols. According to compositional data, borage seed oil contains approximately 1,320 mg/kg of δ-tocopherol. Additional fatty acids in borage oil include linoleic, oleic, palmitic, stearic, eicosenoic, and erucic acids.
3.2 Pyrrolizidine Alkaloids
Borage plant parts contain pyrrolizidine alkaloids (PAs) that are toxic to the liver and lungs and possibly carcinogenic. The herb contains toxic pyrrolizidine alkaloids (lycopsamine, supinidine, amabiline, and intermedine), mainly affecting the liver parenchyma.
The amount present in these plant parts is considered to be low — less than 0.001% dry weight — but borage leaf teas may contain very high, possibly unsafe levels of pyrrolizidine alkaloids according to the EFSA (2016). Borage flower contains the pyrrolizidine alkaloid thesinine, which is considered to be nontoxic. Pyrrolizidine alkaloids in borage are not extracted with borage seed oil, and for this reason, products made from the oil would not be expected to contain PAs.
3.3 Phenolic Compounds
Apart from fatty acids and pyrrolizidine alkaloids, Borago officinalis also contains flavonoids, mucus compounds (mucilage), tannins, mineral salts, organic acids, saponins, vitamins, and essential oil.
Using high-performance liquid chromatography (HPLC), six phenolic acids have been detected in borage seed extract, namely chlorogenic, trans-cinnamic, gallic, rosmarinic, p-coumaric, and syringic acids, while rosmarinic acid comprises the majority of the polyphenolics.
The presence of four flavonoids — astragalin, kaempferol 4-glucoside, rutoside, and vitexin — and eight phenolic acids — caffeic, chlorogenic, 3,4-dihydroxyphenylacetic, ferulic, p-hydroxybenzoic, protocatechuic, rosmarinic, and syringic acids — has been confirmed in B. officinalis extracts by HPLC-DAD analysis.
Phenolic characterisation of borage by-product extracts has further identified nine compounds, with epigallocatechin and rosmarinic acid as the major constituents.
3.4 Other Constituents
Several additional metabolites have been reported, including resins, tannins, ascorbic acid, niacin, beta-carotene, riboflavin, silicic acid, thiamine, choline, arabinose, and polyphenolics.
The mucilage constituent has an expectorant-like action, and malic acid has a mild diuretic effect. The tannin constituent may have mild astringent and constipating actions.
The wound-healing properties of Borago officinalis are attributed to bioactive compounds such as mucilage, allantoin, and phenolic antioxidants.
4. Mechanisms of Action
4.1 The GLA–DGLA–Eicosanoid Pathway
The principal proposed mechanism of borage's pharmacological activity centres on the metabolism of GLA to anti-inflammatory mediators. GLA is further elaborated to the 20-carbon fatty acid dihomo-gamma-linolenic acid (DGLA), a key metabolite for the synthesis of the anti-inflammatory prostaglandins of the 1-series (e.g., PGE1) and 15-(S)-hydroxy-8,11,13-eicosatrienoic acid (15-HETrE) by different types of cells. Theoretically, supplementation with GLA might bypass the rate-limiting step in biosynthesis, providing more of these anti-inflammatory modulators.
GLA is metabolised to dihomo-gamma-linolenic acid (DGLA; 20:3 omega-6), the immediate precursor of prostaglandin E1 (PGE1), an eicosanoid with anti-inflammatory and immunoregulatory properties. In addition, GLA cannot be converted to inflammatory leukotrienes by 5-lipoxygenase.
Instead, GLA is converted to 15-hydroxy DGLA, which has the virtue of suppressing 5-lipoxygenase activity. GLA and DGLA also modulate immune responses in an eicosanoid-independent manner by acting directly on T lymphocytes, and GLA suppresses acute and chronic inflammation, including arthritis, in animal models.
4.2 TNF-α Suppression via cAMP
GLA can increase cAMP levels, which suppress synthesis of TNF-alpha, an inflammatory mediator linked to rheumatoid arthritis. GLA is metabolised to DGLA, the immediate precursor of PGE1, an eicosanoid signalling molecule with immunoregulatory and anti-inflammatory properties. Elevating PGE1 levels leads to enhanced cyclic adenosine monophosphate (cAMP) activity, which suppresses the inflammatory cytokine TNF-α.
4.3 Blocking Pro-inflammatory Arachidonic Acid Cascades
GLA can be converted to the prostaglandin precursor DGLA, and DGLA can block the transformation of arachidonic acid to leukotrienes and other prostaglandins. Under physiological conditions, the conversion of GLA into DGLA not only acts as the precursor of anti-inflammatory compounds but also inhibits the formation of pro-inflammatory eicosanoids from arachidonic acid (AA).
4.4 Delta-6 Desaturase Bypass
Although direct proof is lacking, it has been hypothesised that patients with atopic dermatitis have impaired activity of the delta-6 desaturase enzyme, affecting metabolism of linoleic acid to GLA. Dietary supplementation with borage oil provides pre-formed GLA, bypassing the rate-limiting delta-6 desaturase step.
4.5 Skin-Related Mechanisms
EFAs play a vital role in skin structure and physiology. EFA deficiency replicates the symptoms of atopic dermatitis, and patients with atopic dermatitis have been reported to have imbalances in EFA levels.
4.6 Genetic Variation in Response
Individual genetic variation in fatty acid desaturase has been proposed as a gene–diet interaction to explain the heterogeneity of anti-inflammatory effects seen in clinical trials. One study demonstrated that borage oil elevated serum GLA and DGLA in an rs174537 genotype-dependent manner, suggesting that "one size fits all" supplementation may not be appropriate.
5. Scientific Evidence by Health Area
5.1 Rheumatoid Arthritis
In several randomised, placebo-controlled trials in RA patients, GLA in borage or primrose seed oils reduced synovitis and the need for nonsteroidal anti-inflammatory agents. Multiple studies demonstrate significant improvements in morning stiffness, joint pain, and overall disease activity with GLA supplementation at 1.4–2.8 g daily.
Some clinical trials suggest borage oil may help reduce inflammation and pain associated with arthritis. A key double-blind, randomised, placebo-controlled trial (Zurier et al., Arthritis & Rheumatism, 1996) is frequently cited in this context. The amounts of GLA from borage used in successful double-blind trials were 1.4–2.8 grams daily for at least two months.
Some evidence exists for the use of borage in inflammatory diseases such as rheumatoid arthritis. Borage has been promoted for rheumatoid arthritis, skin inflammation, diabetic nerve pain, menopausal symptoms, and gastrointestinal issues, but research shows only moderate support for its use to relieve rheumatoid arthritis symptoms. Overall, rheumatoid arthritis represents the application area with the strongest available clinical evidence for borage oil, though the body of evidence is still limited in size and methodological quality.
5.2 Atopic Dermatitis and Skin Disorders
Borage oil is of interest for atopic dermatitis because it contains two to three times more GLA than evening primrose oil. A published systematic review identified 12 clinical trials of oral or topical borage oil for treatment of atopic dermatitis and one preventive trial.
The results of studies of borage oil for the treatment of atopic dermatitis were highly variable, with the effect reported to be significant in five studies, insignificant in five studies, and mixed in two studies. Borage oil given to at-risk neonates did not prevent the development of atopic dermatitis. However, the majority of studies showed at least a small degree of efficacy or were not able to exclude the possibility that the oil produces a small benefit. Overall, the data suggest that nutritional supplementation with borage oil is unlikely to have a major clinical effect but may be useful in some individual patients with less severe atopic dermatitis who are seeking an alternative treatment.
Several clinical studies have shown the oil to be ineffective at treating atopic eczema; its efficacy to treat eczema was not better than placebo when taken orally. Two clinical trials do not support its use for skin inflammation such as atopic dermatitis.
Applying borage oil in infants and children with seborrheic dermatitis or atopic dermatitis also normalised their skin barrier function, based on a 2018 study. Overall, the evidence for atopic dermatitis is mixed and currently insufficient to support a strong clinical recommendation.
5.3 Acute Respiratory Distress Syndrome (ARDS)
There is some evidence that borage seed oil, when taken by mouth in combination with eicosapentaenoic acid (EPA), might reduce the number of days spent in the intensive care unit (ICU) and the length of time a breathing machine is needed by patients with acute respiratory distress syndrome (ARDS).
Borage oil might reduce the number of days that patients with (or at risk for) ARDS spend in intensive care. A study conducted on 146 patients in teaching hospitals across the US found that those who were tube fed an EPA+GLA diet showed greater improvements and shorter ICU stays than patients fed a standard diet.
However, more recent evidence is less favourable: more recent prospective, randomised trials of fish oils and borage oil in ARDS have shown no benefit. The evidence in ARDS is therefore considered preliminary and contradictory.
5.4 Asthma and Respiratory Function
In a small study, a borage extract improved some asthma symptoms, including cough. Additional studies are needed.
In human studies, dietary supplementation with borage and echium seed oils produced anti-inflammatory effects in mild asthmatics by altering polyunsaturated fatty acid levels and attenuating leukotriene production. Evidence in asthma remains preliminary and limited to small studies.
5.5 Preterm Infant Development
Infant formula supplemented with fatty acids from borage oil and fish oils seems to improve growth and development of the nervous system in infants born early, especially boys. A study published in the Journal of Pediatrics showed that preterm infants given formula that included borage oil and fish oils showed greater improvement than those given standard formula. This evidence is preliminary and based on a small number of trials.
5.6 Premenstrual Syndrome and Hormonal Symptoms
GLA controls the body's production of prostaglandins, which are chemical messengers that regulate processes such as the reproductive cycle as well as female hormonal balance. Research suggests that symptoms of premenstrual syndrome (PMS) may be the consequence of dysfunctional prostaglandin regulation and that women with PMS may have abnormal sensitivities to normal prolactin levels, a phenomenon related to low PGE1 levels. Evidence specifically for borage oil in PMS from controlled clinical trials is limited.
5.7 Seborrhoeic Dermatitis in Infants
Tollesson and Frithz (1993), published in the British Journal of Dermatology, reported topical borage oil as an effective treatment for infantile seborrhoeic dermatitis. Applying borage oil in infants and children with seborrhoeic dermatitis also normalised skin barrier function. Evidence is limited to a small number of studies.
5.8 Cancer Prevention: Preclinical Evidence Only
Preclinical studies suggest antimutagenic, cytotoxic, and chemopreventive effects. One published PMC study reports the first evidence proving the antigenotoxic and anticarcinogenic properties of two B. officinalis varieties (wild and cultivated), as well as of their major phenolics: rosmarinic, syringic, and sinapic acids. B. officinalis exerts DNA protection and anticarcinogenic effects as do its component rosmarinic acid and the mixture of the main phenolics presented in the plant. This evidence is confined to in vitro and in vivo preclinical models; no human clinical trials have been conducted.
5.9 Mood and Depression
No scientific evidence supports the use of borage for treating depression. The traditional association between borage and mood elevation has no verified clinical trial evidence.
5.10 Diuretic and Expectorant Effects
Borage plant parts have been used as a mild diuretic, expectorant, and to induce sweating, and in proprietary mixtures promoted to increase milk supply; however, no scientifically valid clinical trials support these uses.
6. Body Systems Associated with Borage
- Musculoskeletal and inflammatory: Several animal and clinical trials have suggested the protective role of borage oil and GLA in the treatment of non-communicable diseases, possibly due to their antioxidative and anti-inflammatory activities.
- Dermatological: Some clinical studies suggest that borage oil supplementation may support skin health, especially in conditions like atopic dermatitis and eczema, by improving skin barrier function and reducing dryness.
- Respiratory: The mucilage constituent has an expectorant-like action.
- Cardiovascular: Borage oil, containing 20–26% GLA, has paradoxical anti-inflammatory properties that complement omega-3 fish oils through distinct prostaglandin pathways. While fish oils enhance PG3 production, GLA specifically promotes PGE1 synthesis.
- Reproductive and hormonal: GLA and DGLA influence prostaglandin-mediated reproductive and menstrual physiology.
- Tissue repair and wound healing: The wound-healing properties of Borago officinalis are attributed to bioactive compounds such as mucilage, allantoin, and phenolic antioxidants. These constituents stimulate fibroblast proliferation, angiogenesis, and collagen synthesis — key processes in tissue regeneration.
- Serotonergic: Although aerial parts of borage demonstrate affinity for the serotonin transporter, toxicity profiles preclude its further development as an herbal drug.
7. Dosage Forms and Doses Reported in Clinical Studies
Important note: The doses below are those reported in published research and clinical trial contexts; they are not prescriptive recommendations.
- Rheumatoid arthritis: The amounts of GLA from borage used in successful double-blind trials were 1.4–2.8 grams daily for at least two months.
- Atopic dermatitis (oral): 360 mg of GLA daily from borage oil has been used in clinical attempts to treat people with eczema, though controlled research has not supported consistent benefit at this dose.
- Seizure case report dose: A case of continuous seizure activity was reported in a healthy 41-year-old woman with short-term use (one week) of borage oil at 1,500 to 3,000 mg per day.
- UPA safety threshold: Consumption of 1–2 g of borage seed oil daily can result in an intake of toxic unsaturated pyrrolizidine alkaloids (UPAs) approaching 10 μg. The German Federal Health Agency specifies consumption to be limited to 1 μg of UPA daily.
8. Safety Considerations and Drug Interactions
8.1 Pyrrolizidine Alkaloids: Hepatotoxicity
Borage plant parts contain pyrrolizidine alkaloids that are toxic to the liver and lungs and possibly carcinogenic. Borage oil may contain the pyrrolizidine alkaloid amabiline, which is hepatotoxic, leading to a risk of liver damage. Patients should use borage oil that is certified free of toxic unsaturated pyrrolizidine alkaloids (UPAs).
Borage oil products should be certified free of toxic UPAs, with no more than 0.5–1 microgram of UPAs per gram of borage oil. The German Federal Health Agency recommends that consumption of UPAs should be limited to no more than 1 microgram daily.
Bioactivation of pyrrolizidine alkaloids occurs mostly in the liver, and for this reason, this organ is the most affected by toxicity. Based on EFSA data, the UK's Food Standards Agency recommends that borage leaf teas be avoided.
8.2 Pregnancy and Breastfeeding
Borage oil may be unsafe during pregnancy because preliminary studies suggest borage oil has a teratogenic effect and that its prostaglandin E agonist action may cause premature labour. Pyrrolizidine alkaloids might be excreted into breastmilk. Borage seed oil is generally well tolerated in adults; however, only products certified as pyrrolizidine alkaloid-free should be used.
8.3 Seizure Risk
A case report describes the development of seizures ultimately progressing to continuous seizures in an otherwise previously healthy 41-year-old woman, with short-term use (1 week) of borage oil at 1,500 to 3,000 mg/day. Seizures have been reported as a complication of ingestion of borage oil in doses of 1,500 to 3,000 mg daily, although a mixed review of borage oil's effect on seizure thresholds indicates that borage oil quality varies.
8.4 Blue Baby Syndrome (Methaemoglobinaemia)
Multiple cases in Spain have clearly linked blue baby syndrome (an infant blood disorder) to ingestion of borage, which was tested as a purée and is high in nitrates. Breastfeeding was also a contributing factor. Infants are unable to process large amounts of nitrates.
8.5 Mistaken Identity Risk
Near-fatal poisoning from mistaken plant identity has been recorded: borage was confused with the toxic plant foxglove, causing accidental poisoning in an otherwise healthy 58-year-old woman.
8.6 Drug Interactions
Hepatotoxic drugs: Because borage contains low concentrations of substances that have been associated with liver damage, it should not be used with drugs that could affect the liver, such as anabolic steroids, phenothiazine, or ketoconazole. The levels of hepatotoxic PA metabolites may be increased when borage is used with CYP3A4 inducers such as carbamazepine, phenytoin, and rifampin.
Anticoagulants and antiplatelets: In a small study of humans on several months of supplementation with GLA from evening primrose oil, 9 of 12 patients had a significant increase in bleeding time. By extension, caution should be taken as borage oil is approximately 25% GLA, while evening primrose oil is about 10% GLA.
Anticonvulsants and CNS drugs: Borage may lower the seizure threshold and should not be used with drugs that can also have this effect, such as tricyclic antidepressants and phenothiazines. Concomitant use with phenothiazines and tricyclic antidepressants may increase seizure risk, and dosage requirements of antiepileptics may need to be increased.
NSAIDs: Theoretically, concomitant use of NSAIDs would decrease the effects of borage oil, as NSAIDs interfere with prostaglandin E synthesis.
General GLA interaction with anticoagulants: Borage oil's GLA content may enhance the effects of blood-thinning medications, increasing bleeding risk.
8.7 General Tolerability
Borage oil is well tolerated in the short-term in most adults when PA-free products are used. Common side effects can include digestive issues such as bloating, nausea, and diarrhoea. Borage seed oil can have toxic effects on the liver; its chronic use should be avoided, especially by patients with liver disease or women who are pregnant or breastfeeding.
References
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