What is it?
Evening primrose oil (EPO), comes from the seeds of the evening
primrose plant. Like black currant seed oil and borage oil, EPO contains
gamma linolenic acid (GLA), a fatty acid that the body converts to a
hormone-like substance called prostaglandin E1 (PGE1).
PGE1 has anti-inflammatory properties and may also act as a blood
thinner and blood vessel dilator. The anti-inflammatory properties of
EPO have been studied in double-blind research with people suffering
from rheumatoid arthritis. Some, but not all, studies have reported that
EPO supplementation provides significant benefit to these people.1
GLA, the primary active ingredient in EPO, has anticancer activity in
test tube studies2 and in some,3 but not all,4
animal studies. Injecting GLA into tumors has caused regression of
cancer in people in preliminary research.5 Preliminary
evidence in people with cancer suggested "marked subjective
improvement,"6 though not all studies find GLA helpful.7
EPO has been reported to lower cholesterol levels in people in some,8
but not all,9 research.
EPO supplementation has been shown to improve skin itching, redness,
and dryness associated with kidney dialysis.10 11
Linoleic acid, a common fatty acid found in nuts and seeds and most
vegetable oils (including EPO), should theoretically be converted to
PGE1; but many things can interfere with this conversion, including
disease; the aging process; saturated fat; hydrogenated oils; blood
sugar problems; and inadequate vitamin C, magnesium, zinc, and B
vitamins. Supplements that provide GLA circumvent these conversion
problems, leading to more predictable formation of PGE1.12
1. Joe LA, Hart LL. Evening primrose oil in
rheumatoid arthritis. Ann Pharmacother 1993;27:1475-7 [review].
2. Dippneaar N, Booyens J, Fabbri D, Katzeff IE.
The reversibility of cancer: evidence that malignancy in melanoma cells
is gamma linolenic acid deficiency-dependent. S Afr Med J
1982;62:505-9.
3. Pritchard GA, Mansel RE. The effects of
essential fatty acids on the growth of breast cancer and melanoma. In
Omega-6 Essential Fatty Acids: Pathophysiology and Roles in Clinical
Medicine. Horrobin DF (ed). New York: Alan R Liss, 1990, 379-90.
4. Lee JH, Sugano M. Effects of linoleic and gamma-linolenic
acid on 7,12-dimethylbenz(a)anthracene-induced rat mammary tumors.
Nutr Rep Int 1986;34:1041.
5. Naidu MRC, Das UN, Kshan A. Intratumoral gamma-linolenic
acid therapy of human gliomas. Prostaglandins Leukot Essent Fatty
Acids 1992;45:181-4.
6. Van der Merwe CF, Booyens J. Oral gamma-linolenic
acid in 21 patients with untreatable malignancy. An ongoing pilot open
clinical trial. Br J Clin Pract 1987;41:907-15.
7. McIllmurray MB, Turkie W. Controlled trial of
gamma linolenic in Duke’s C colorectal cancer. Br Med J
1987;294:1260.
8. Ishikawa T, Fujiyama Y, Igarashi O, et al.
Effects of gammalinolenic acid on plasma lipoproteins and
apolipoproteins. Atherosclerosis 1989;75:95-104.
9. Boberg M, Vessby B, Selinus I. Effects of
dietary supplementation with n-6 and n-3 long-chain polyunsaturated
fatty acids on serum lipoproteins and platelet function in
hypertriglyceridaemic patients. Acta Med Scand 1986;220:153-60.
10. Yoshimoto-Furuie K, Yoshimoto K, Tanaka T, et
al. Effects of oral supplementation with evening primrose oil for six
weeks on plasma essential fatty acids and uremic skin symptoms in
hemodialysis patients. Nephron 1999;81:151-9.
11. Tamimi NA, Mikhail AI, Stevens PE. Role of
gamma-linolenic acid in uraemic pruritus. Nephron 1999;83:170-1
[letter].
12. Horrobin DF. The importance of gamma-linolenic
acid and prostaglandin E1 in human nutrition and medicine. J
Holistic Med 1981;3:118-39.
13. Horrobin DF, Manku M, Brush M, et al.
Abnormalities in plasma essential fatty acid levels in women with
pre-menstrual syndrome and with non-malignant breast disease. J Nutr
Med 1991;2:259–64.
14. Keen H, Payan J, Allawi J, et al. Treatment of
diabetic neuropathy with gamma-linolenic acid. Diabetes Care
1993;16:8–15.
15. Horrobin DF. Essential fatty acid metabolism in
diseases of connective tissue with special reference to scleroderma and
to Sjogren’s syndrome. Med Hypotheses 1984;14:233–47.
16. Horrobin DF, Campbell A. Sjogren’s syndrome and
the sicca syndrome: the role of prostaglandin E1 deficiency. Treatment
with essential fatty acids and vitamin C. Med Hypotheses
1980;6:225–32.
17. Vaddadi KS, Gilleard CJ. Essential fatty acids,
tardive dyskinesia, and schizophrenia. In Omega-6 Essential Fatty
Acids: Pathophysiology and Roles in Clinical Medicine, ed. DF
Horrobin. New York: Alan R Liss, 1990, 333–43.
18. Manku MS, Horrobin, DF, Morse NL, et al.
Essential fatty acids in the plasma phospholipids of patients with
atopic eczema. Br J Derm 1984;110:643.
19. Horrobin DF. Essential fatty acids in clinical
dermatology. J Am Acad Dermatol 1989;20:1045–53.
20. Mansel RE, Pye JK, Hughes LE. Effects of
essential fatty acids on cyclical mastalgia and noncyclical breast
disorders. In Omega-6 Essential Fatty Acids: Pathophysiology and
Roles in Clinical Medicine, ed. DF Horrobin. New York: Alan R Liss,
1990, 557–66.
21. Keen H, Payan J, Allawi J, et al. Treatment of
diabetic neuropathy with gamma-linolenic acid. Diabetes Care
1993;16:8–15.
22. Horrobin DF. Essential fatty acid metabolism in
diseases of connective tissue with special reference to scleroderma and
to Sjogren’s syndrome. Med Hypotheses 1984;14:233–47.
23. Vaddadi KS, Gilleard CJ. Essential fatty acids,
tardive dyskinesia, and schizophrenia. In Omega-6 Essential Fatty
Acids: Pathophysiology and Roles in Clinical Medicine. Horrobin DF
(ed). New York: Alan R Liss, 1990, 333–43.
24. Schalin-Karrila M, Mattila L, Jansen CT, et al.
Evening primrose oil in the treatment of atopic eczema: effect on
clinical status, plasma phospholipid fatty acids and circulating blood
prostaglandins. Br J Dermatol 1987;117:11–9.
25. Glen AIM, Glen EMT, MacDonnell LEF, et al.
Essential fatty acids in the management of withdrawal symptoms and
tissue damage in alcoholics, presented at the 2nd International Congress
on Essential Fatty Acids, Prostaglandins and Leukotrienes, London,
Zoological Society. March 24–7, 1985, [abstract 53].
26. Vaddadi KS. The use of gamma-linolenic acid and
linoleic acid to differentiate between temporal lobe epilepsy and
schizophrenia. Prostaglandins Med 1981;6:375–9.
27. Holman CP, Bell AFJ. A trial of evening
primrose oil in the treatment of chronic schizophrenia. J Orthomol
Psychiatr 1983;12:302–4.