Oenothera biennis - Evening Primrose

Description

Annual or biennial, the plant is 1 - 3 m in height. Leaves are arranged in basal rosette before antheisi, lanceolate, 10 - 22 cm long, 1 cm wide, margins undulate or minutely toothed. The flowers are yellow, fragrant, 2 - 3 cm long, and solitary in the leaf axils. The fruit is a dry pod to 4 cm, with numerous minute seeds. Seeds are 1.5 mm long, dark gray to black with irregular sharp edges. Evening Primrose originated in North America but now grows wild throughout Europe and parts of Asia. It is primarily cultivated for its oil in Europe and North America.

Part used

Oil from the seeds, formerly bark and leaves.(1)

Constituents

Evening Primrose Oil is roughly 14% of the seed — 50 to 70% cis-linoleic acid, 7 to 10% cis-gamma-linolenic acid (GLA), plus cis-6,9,12-octadecatrienoic acid, oleic, palmitic and steric acids, campesterol and beta-sitosterol steroids.(2)

Mode of action

In the last ten years, over 300 extensive scientific investigations into EPO have been conducted. Over half were double blind studies. Research into EPO continues. GLA and EPO have a number of proven clinical.

Applications:

A double blind study conducted at Bristol University in England, carried out on both adults and children, determined that EPO in doses of 3 grams a day produced substantial changes in eczema patients. Results usually occur within eight weeks and the dose decrease to half the amount after three months. Cell membranes start to saturate with PUFA.

Three double blind studies at the universities of Dundee, Wales and Helsinki reveal that EPO is very effective in treating cases of P.M.S. Another study consisted of 150 women. These women failed to respond to other P.M.S. treatment, yet 67% of them found relief and an additional 25%, found partial relief with EPO. The dosage was eight capsules of EPO daily throughout the menstrual cycle for three months. Dosage was reduced to half the amount at that stage.](14-16)

EPO`s power to lower blood cholesterol is 100-163 times as effective as other vegetable oils. These results occur without dietary changes.(17-20) Strangely, EPO did not lower cholesterol in patients with normal or low cholesterol. LDL was the form of cholesterol changed in all subjects treated. There was no effect on HDL. LDL/HDL ratio was 3.20:1 before treatment and 2.38:1 after treatment.

A Scottish study (involving more than 200 alcoholics) indicated EPO substantially reducing the side effects of alcohol withdrawal and the need for tranquilizers during withdrawal.[21](21) EPO returned liver function to normal rapidly. This process produced improvements in brain function. EPO lowers the craving for alcohol. A year later, significantly lower numbers in the EPO group had not returned to drinking in comparison to the placebo group.

A large study at Glasgow University in Scotland and a controlled study at University of Copenhagen, have shown that EPO is effective in controlling Dry Eye Syndrome (Sjögren Syndrome). (22)

In England a Hyperactive Children`s Support Group started administering EPO to over 200 children. Four out of five responded (the youngest responding best).

EPO lowers blood pressure in hypertensive models during animal studies. Several studies on humans are presently under way. One study on pregnant women found that blood pressure was lowered through the use of EPO.[24] In another study on obese patients at Tulane University, EPO apparently reduced blood pressure in mildly hypertensive cases.(25)

A five year study at the University of Rotterdam in Holland found high doses of LA reduced damage done to eyes, heart and kidneys in diabetics.](26) Substantial improvements in blood sugar levels can occur after administration of large amounts of GLAs.

Double blind studies were conducted in the late seventies at Ninewells Hospital and medical school, Dundee, and Welsh School of Medicine. These studies were conducted on women with cyclical breast symptoms. These studies reveal significant reduction in pain, tenderness, and lumpiness during EPO ingestion. An increased effect was also found if vitamin C (750 mg.) was added to the regime. Non-cyclic breast symptoms showed little change.

Use of evening primrose oil in the treatment of PMS (premenstrual syndrome) has been controversial. Meta-analysis in the mid-nineties indicated that there was no well-established benefit for use of EPO.(3) Recent research into the use of gamma-linoleic acid for reducing arthritis inflammation has yielded positive results at dosage levels of 2.8 gm/day, well above those recommended for commercial preparations.(4)

Therapeutic action

Astringent, sedative, antispasmodic, demulcent, emollient, antiarteriosclerotic.

Other

Folklore

Evening primrose (Oenothera biennis) has a long history of medicinal use. One of the first plants the early settlers of North America brought back to Europe, it picked up the common name, King`s Cure-All. Its primary use was for skin diseases and stomach ailments. Evening Primrose was a folk remedy used for allergy, cancer, coughs, throat irritation, earache, congestive headache, sinus inflammation and jaundice.(5) Grieve notes its application for dyspepsia, torpor of the liver, and in certain female complaints, such as pelvic fullness.(6) The Algonquin Indians used the seeds of Evening primrose for treating skin diseases and breathing problems.(12) Oenothera species were used widely by Native American tribes. O. biennis was used topically and internally by the Iroquois and Cherokee.(7)

Dosage

Standardized capsules - 1 - 2 caps, 3x daily.(8)

Toxicity and Contraindications

No precautions or adverse reactions are reported for therapeutic dosages.(9)

Official Recognition and Medical References

UK - approved for atopic eczema
US - dietary supplement, formerly considered ``food additive`` and not approved for treatment of any condition.
Canada - dietary supplement to increase fatty acid intake(10)

References

1.Grieve, M., A Modern Herbal, Jonathan Cape, London, 1931, p. 658.
2.Leung, A.Y.,Encyclopedia of common natural ingredients used in food, drugs, and cosmetics, John Wiley & Sons Inc., New York, 1980.
3.Budeiri, D., et al., Is evening primrose oil of value in the treatment of premenstrual syndrome? Control Clin Trials 1996 Feb;17(1):60-8.
4. Zurier, R., et al., gamma-Linolenic acid treatment of rheumatoid arthritis. A randomized, placebo-controlled trial, Arthritis Rheum 1996 Nov;39(11):1808-17.
5. Zurier, R., et al., gamma-Linolenic acid treatment of rheumatoid arthritis. A randomized, placebo-controlled trial, Arthritis Rheum 1996 Nov;39(11):1808-17.
6. Grieve, M., Ibid.
7. Moerman, D.E., Medicinal Plants of Native America, University of Michigan Museum of Anthropology, Technical Reports, Number 19, Ann Arbor, Michigan, 1986, Vol.1, p. 310.
8. PDR for Herbal Medicines (First Edition), Medical Economics Company, Montvale, NJ, 1998, p. 999.
9. PDR for Herbal Medicines (First Edition), Ibid.
10. Leung, A.Y. and S. Foster, Encyclopedia of Common Natural Ingredients: Used in Food, Drugs, and Cosmetics, John Wiley & Sons, Inc., New York, 1996, p. 236.