The evening primrose, oenothera spp., is not in fact a primrose but is related to the garden flowers clarkia and gotedia and also to the rose bay willow-herb. It has a two year growth cycle; during the second year it bears yellow flowers and, in late summer or early autumn, seed pods.
American Indians applied its leaves as a poultice to heal wounds, and brewed a cough mixture from its roots. Now its seeds are claimed to have medicinal uses ranging from relieving pre-menstrual syndrome to management of multiple sclerosis, alcoholism and atopic eczema.
The seeds contain approximately 15% protein, 24% oil and 43% cellulose and lignin. The fatty acids in the oil are thought to be important to health because the oil contains 65-85% linoleic acid (LA) and 7-15% gamma linoleic acid (GLA): LA is an essential fatty acid for the body which it cannot make but which it converts to GLA. GLA is one of the components of cells and a precursor of prostaglandins which regulate many body functions. However, the LA GLA conversion step may be blocked by a range of factors including excessive levels of blood cholesterol, a high proportion of certain fatty acids in the diet, ageing, alcohol intake and diabetes.
Supplementing the diet with evening primrose oil (EPO) by-passes the conversion step, thus providing for the presence of GLA in the body. A recent World Health Organisation report suggested that 3% of the total calorific intake of adults should be in the form of essential fatty acids, this figure rising to 5-6% for children and pregnant and lactating women. GLA can be provided by several other sources as well, e.g. borage oil and blackcurrant oil, both of which contain a higher concentration of GLA than EPO but not as much LA.
The quality and composition of EPO used in commercial manufacturing is currently the subject of much research and monitoring work. In the UK research is concentrated on obtaining GLA from other sources e.g. by fermentation from the fungus mucor javanicus.
A concentrated oil from evening primrose, borage and blackcurrant seeds, is now undergoing clinical trials and may be used in second generation oil products of the future. EPO is already used in a variety of beauty and hygiene products, including cosmetic and skin care products, shampoos and soaps.
Trials have been curried out to investigate claims of the effectiveness of EPO in treating many diseases and conditions, including multiple sclerosis, cardiovascular disease, asthma, atopic eczema, cancer, obesity and premenstrual syndrome. So far the results have been variable but some genuine clinical effects have been seen.
Millions of dollars have been and are being spent on developing new methods of extracting useful natural products for the benefit of mankind. We are now seeing a widespread desire to return to natural resources to cure various ailments. Let us hope that, before mankind destroy their environment, they will come to realize the importance of nature’s medicine-cabinet, and give thanks where it is due. Without that giving of thanks, mankind will not practise the humility and compassion necessary if our common resources are to be preserved both for ourselves and for future generations.