Plant Profiler

Borage seed oil (Borago officinalis)

Borage seed oil (Borago officinalis) Image
Synonyms / Common Names / Related Terms
Borage, borage oil, Borago officinalis, borage seed, gamma-linolenic acid (GLA), Glandol®, n-6 polyunsaturated fatty acids (PUFA), n-6 PUFA, starflower, starflower oil.

Mechanism of Action


  • Constituents: Borage's main constituent of interest is gamma-linolenic acid (GLA), which is responsible for most of the pharmacological effects below.5 Borage oil also contains the microsomal desaturase, Delta6-fatty acid desaturase, which shows homology to the small hemoprotein cytochrome (Cyt) b5.15
  • Antibacterial activity: In an in vitro study of 25 botanical aqueous extracts, borage was one of the most efficient antibacterial extracts against Helicobacter pylori.4
  • Antihyperlipidemic effects: According to a study of GLA in humans, GLA (source unspecified) decreased plasma triglyceride levels and increased HDL-cholesterol concentration.12
  • Anti-inflammatory effects: Based on recent research, Kast et al. hypothesized that borage oil's anti-inflammatory effects may be due to the gamma-linolenic acid component of borage oil, which suppresses tumor necrosis factor-alpha synthesis by increasing prostaglandin E and cAMP levels.9 The authors continued that if this biochemical path is correct, then "concomitant non-steroidal anti-inflammatory drug use would tend to undermine borage oil effects, and borage oil would be contraindicated in pregnancy given the teratogenic and labor inducing effects of prostaglandin E agonists."
  • Antiplatelet effects: According to a review article and a study on GLA (source unspecified), borage seed oil may potentially increase the risk of bleeding or potentiate the effects of warfarin therapy.6,12 However, in a study of healthy volunteers, the therapeutic dosage of 3g daily of borage oil supplementation did not affect platelet aggregation.13
  • Cardiovascular effects: In a randomized, double-blind study, normotensive subjects ingested 4.5mL daily for four weeks to assess the effects of dietary safflower (control, N=10), borage (N=9), and fish oil (N=10) on cardiovascular responses to lower-body negative pressure.14 Borage oil significantly altered plasma norepinephrine and vasoconstrictor responses to -40 mmHg lower-body negative pressure, as well as the reflex vasodilation on its cessation. The authors hypothesize that borage oil may augment arterial baroreflex control of vascular resistance.
  • Dermatologic activity: In a study of the influence of nine lipids on normal skin and skin irritated by sodium lauryl sulfate, a single application of borage oil had no effect on irritation.16
  • Fatty acid activity: Various studies have been conducted to elucidate the effect that borage oil or its primary constituent, gamma-linolenic acid (GLA), has on serum and cellular fatty acids. According to studies in humans, ingestion of GLA increases its metabolite dihomo-gamma-linolenic acid (DGLA).5,11,1,17,18 The increase of DGLA in turn increases the level of its metabolite 15-hydroxyeicosatrienoic acid (15-HETrE) and other chemicals, which are known anti-inflammatories and antiproliferatives.5,1 GLA also slightly increases arachidonic acid (AA) levels.17,19,11 However, some researchers hypothesize that GLA should increase arachidonic acid levels much higher, and thus, arachidonic acid may be inhibited by eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA). Nonetheless, this interaction does not seem to be occurring, and GLA has a limited impact on arachidonic acid levels.19,11,18 Interestingly, GLA consumed with alpha-linolenic acid (ALA) significantly, yet negligibly, increased omega 3 and eicosapentaenoic acid in vegans' serum cholesterol.10 In another human study, a combination of GLA and stearidonic acid also increased the proportion of eicosapentaenoic acid in some lipid fractions.17
  • Hematological effects: In an in vitro study in platelets of men who had consumed borage oil, borage oil altered the fatty acid composition of the platelet phospholipids, including a reversible rise in the DGLA and a decrease in n-3 polyunsaturated fatty acids.18
  • Immunological effects: In an in vitro study, GLA from borage oil dose-dependently reduced tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-10 levels to 60% of control levels.2 These effects were not altered by the addition of indomethacin, indicating that DGLA affects TNF-alpha and IL-10 levels independently of COX activation. In addition, ingestion of GLA seems to reduce polymorphonuclear generation of proinflammatory leukotriene B4, although this effect does not appear to be dose-dependent.7 In rheumatoid arthritis subjects, GLA suppressed T lymphocyte proliferation, which is related to the propagation of joint tissue injury.8 This finding is supported by a more in-depth animal study, in which mice fed borage oil had increased T-helper 1-like responses and decreased T-helper 2-like responses, and possibly enhanced suppressor cell or T-helper 3-like activity.3


  • Absorption: In a study using full thickness human skin, Karia et al. simulated the absorption of tamoxifen and borage oil into breast tissue.20 The tissue was dosed with 500mcL saturated solution of tamoxifen in borage oil (25% GLA). The cumulative permeation at 24 hours was 764.3 ± 94.2mcg/cm2 for GLA and 5.44 ± 0.67mcg/cm2 for tamoxifen; the tamoxifen permeation is comparable to the amount of tamoxifen associated with cancerous breast tissue from a 20mg oral dose. The ratio of GLA/tamoxifen permeated at different time points was quite consistent, which the authors hypothesize may be due to the association of 2.5 molecules of GLA with each molecule of tamoxifen in the permeation process.
  • Metabolism: In an in vitro study in human neutrophils, GLA from borage oil rapidly elongated (by the addition of two carbons) to dihomo-gamma-linolenic acid (DGLA), which is incorporated into neutral lipids, specifically triacylglycerides.21 To determine whether DGLA could be mobilized from cellular glycerolipids, neutrophils were stimulated with ionophore A23187 and fatty acid levels were determined. DGLA and arachidonic acid (AA) were both released during stimulation, and the quantities of DGLA mobilized increased threefold after in vitro GLA supplementation.


  1. Fan, Y. Y. and Chapkin, R. S. Importance of dietary gamma-linolenic acid in human health and nutrition. J Nutr 1998;128(9):1411-1414. 9732298
  2. Dooper, M. M., van Riel, B., Graus, Y. M., and M'Rabet, L. Dihomo-gamma-linolenic acid inhibits tumour necrosis factor-alpha production by human leucocytes independently of cyclooxygenase activity. Immunology 2003;110(3):348-357. 14632663
  3. Harbige, L. S. and Fisher, B. A. Dietary fatty acid modulation of mucosally-induced tolerogenic immune responses. Proc Nutr Soc 2001;60(4):449-456. 12069397
  4. O'Mahony, R., Al Khtheeri, H., Weerasekera, D., Fernando, N., Vaira, D., Holton, J., and Basset, C. Bactericidal and anti-adhesive properties of culinary and medicinal plants against Helicobacter pylori. World J Gastroenterol 12-21-2005;11(47):7499-7507. 16437723
  5. Ziboh, V. A., Naguwa, S., Vang, K., Wineinger, J., Morrissey, B. M., Watnik, M., and Gershwin, M. E. Suppression of leukotriene B4 generation by ex-vivo neutrophils isolated from asthma patients on dietary supplementation with gammalinolenic acid-containing borage oil: possible implication in asthma. Clin Dev Immunol 2004;11(1):13-21. 15154607
  6. Heck, A. M., DeWitt, B. A., and Lukes, A. L. Potential interactions between alternative therapies and warfarin. Am J Health Syst Pharm 7-1-2000;57(13):1221-1227. 10902065
  7. Ziboh, V. A. and Fletcher, M. P. Dose-response effects of dietary gamma-linolenic acid-enriched oils on human polymorphonuclear-neutrophil biosynthesis of leukotriene B4. Am J Clin Nutr 1992;55(1):39-45. 1309474
  8. Rossetti, R. G., Seiler, C. M., DeLuca, P., Laposata, M., and Zurier, R. B. Oral administration of unsaturated fatty acids: effects on human peripheral blood T lymphocyte proliferation. J Leukoc Biol 1997;62(4):438-443. 9335312
  9. Kast, R. E. Borage oil reduction of rheumatoid arthritis activity may be mediated by increased cAMP that suppresses tumor necrosis factor-alpha. Int Immunopharmacol 2001;1(12):2197-2199. 11710548
  10. Fokkema, M. R., Brouwer, D. A., Hasperhoven, M. B., Martini, I. A., and Muskiet, F. A. Short-term supplementation of low-dose gamma-linolenic acid (GLA), alpha-linolenic acid (ALA), or GLA plus ALA does not augment LCP omega 3 status of Dutch vegans to an appreciable extent. Prostaglandins Leukot Essent Fatty Acids 2000;63(5):287-292. 11090255
  11. Thijs, C., Houwelingen, A., Poorterman, I., Mordant, A., and van den, Brandt P. Essential fatty acids in breast milk of atopic mothers: comparison with non-atopic mothers, and effect of borage oil supplementation. Eur J Clin Nutr 2000;54(3):234-238. 10713746
  12. Guivernau, M., Meza, N., Barja, P., and Roman, O. Clinical and experimental study on the long-term effect of dietary gamma-linolenic acid on plasma lipids, platelet aggregation, thromboxane formation, and prostacyclin production. Prostaglandins Leukot Essent Fatty Acids 1994;51(5):311-316. 7846101
  13. Bard, J. M., Luc, G., Jude, B., Bordet, J. C., Lacroix, B., Bonte, J. P., Parra, H. J., and Duriez, P. A therapeutic dosage (3 g/day) of borage oil supplementation has no effect on platelet aggregation in healthy volunteers. Fundam Clin Pharmacol 1997;11(2):143-144. 9107561
  14. Mills, D. E., Mah, M., Ward, R. P., Morris, B. L., and Floras, J. S. Alteration of baroreflex control of forearm vascular resistance by dietary fatty acids. Am J Physiol 1990;259(6 Pt 2):R1164-R1171. 2260727
  15. Sayanova, O., Shewry, P. R., and Napier, J. A. Histidine-41 of the cytochrome b5 domain of the borage delta6 fatty acid desaturase is essential for enzyme activity. Plant Physiol 1999;121(2):641-646. 10517856
  16. Loden, M. and Andersson, A. C. Effect of topically applied lipids on surfactant-irritated skin. Br J Dermatol 1996;134(2):215-220. 8746332
  17. Miles, E. A., Banerjee, T., and Calder, P. C. The influence of different combinations of gamma-linolenic, stearidonic and eicosapentaenoic acids on the fatty acid composition of blood lipids and mononuclear cells in human volunteers. Prostaglandins Leukot Essent Fatty Acids 2004;70(6):529-538. 15120716
  18. Barre, D. E. and Holub, B. J. The effect of borage oil consumption on the composition of individual phospholipids in human platelets. Lipids 1992;27(5):315-320. 1328794
  19. Demmelmair, H., Feldl, F., Horvath, I., Niederland, T., Ruszinko, V., Raederstorff, D., De Min, C., Muggli, R., and Koletzko, B. Influence of formulas with borage oil or borage oil plus fish oil on the arachidonic acid status in premature infants. Lipids 2001;36(6):555-566. 11485158
  20. Karia, C., Harwood, J. L., Morris, A. P., and Heard, C. M. Simultaneous permeation of tamoxifen and gamma linolenic acid across excised human skin. Further evidence of the permeation of solvated complexes. Int J Pharm 3-1-2004;271(1-2):305-309. 15129999
  21. Chilton, Lopez, Surette, M. E., Swan, D. D., Fonteh, A. N., Johnson, M. M., and Chilton, F. H. Metabolism of gammalinolenic acid in human neutrophils. J Immunol 4-15-1996;156(8):2941-2947. 8609415

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