EVENING PRIMROSE OIL (EPO)

Physiology and Clinical Effects
Evening primrose oil (EPO), black currant seed oil, and borage oil contain 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 anti-cancer 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 Very 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.

Linoleic acid, a common fatty acid found in nuts, seeds, and most vegetable oils (including EPO), should theoretically convert 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 PGE1.¹⁰

Food Sources
EPO is found primarily in supplements. The active ingredient, GLA, can also be found in black current seed oil and borage oil supplements.

Deficiency Risk and Symptoms
Those with premenstrual syndrome,¹¹ diabetes,¹² scleroderma,¹³ Sjogren’s syndrome,¹⁴ tardive dyskinesia,¹⁵ and eczema,¹⁶ and other skin conditions¹⁷ can have a metabolic block that interferes with the body’s ability to make GLA. In preliminary research, supplementation with EPO has helped people with these conditions.^{18 19 20 21 22}

Though preliminary, double-blind evidence suggests that alcoholics may be deficient in GLA and that alcohol withdrawal may be facilitated with EPO supplementation.²³ Many people in Western societies may be at least partially GLA deficient as a result of aging, glucose intolerance, dietary fat intake, and other problems. Individuals with deficiencies benefit from supplemental GLA intake from EPO, black currant seed oil, or borage oil.

Recommended Dosage
Although many people may have inadequate levels of GLA, the optimal intake for this nutrient remains unknown. Researchers often use 3,000–6,000 mg of EPO per day, which provides approximately 270–540 mg of GLA.

Contraindications
Consistent, reproducible problems from taking EPO have not been reported.

Other nutrients are needed by the body, along with EPO, to make PGE1. Consequently, some experts suggest that magnesium, zinc, vitamin C, niacin, and vitamin B6 should be taken along with EPO.

References:

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, ed. DF Horrobin. 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 Internat 1986;34:1041.
5. Naidu MRC, Das UN, Kshan A. Intratumoral gamma-linolenic acid therapy of human gliomas. Prostaglandins Leukotrienes Essential 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. Horrobin DF. The importance of gamma-linolenic acid and prostaglandin E1 in human nutrition and medicine. J Holistic Med 1981;3:118–39.
11. 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.
12. Keen H, Payan J, Allawi J, et al. Treatment of diabetic neuropathy with gamma-linolenic acid. Diabetes Care 1993;16:8–15 [reviews].
13. Horrobin DF. Essential fatty acid metabolism in diseases of connective tissue with special reference to scleroderma and to Sjogren’s syndrome. Med Hypoth 1984;14:233–47.
14. 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 Hypoth 1980;6:225–32.
15. Vaddadi KS, Gilleadrd 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.
16. 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.
17. Horrobin DF. Essential fatty acids in clinical dermatology. J Am Acad Dermatol 1989;20:1045–53.
18. 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.
19. Keen H, Payan J, Allawi J, et al. Treatment of diabetic neuropathy with gamma-linolenic acid. Diabetes Care 1993;16:8–15.
20. Horrobin DF. Essential fatty acid metabolism in diseases of connective tissue with special reference to scleroderma and to Sjogren’s syndrome. Med Hypoth 1984;14:233–47.
21. Vaddadi KS, Gilleadrd 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.
22. 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. Brit J Dermatol 1987;117:11–9.
23. 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.

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