Research has revealed that the species originated in Mexico and Central America some 70,000 years ago. Four times it colonized North America, each time being almost wiped out by glaciers during successive ice ages. Each new wave of evening primrose cross-pollinated with survivors and so continued the line.
American Indians are supposed to have used the evening primrose for hundreds of years. According to folklore, a tribe called Flambeau Ojibwe was the first to realize the medicinal properties of the evening primrose plant. They used to soak the whole plant in warm water to make a poultice to heal bruises, they used the plant for skin problems and asthma, and brewed a cough mixture from the roots.
From America, the evening primrose spread all over the world. Botanists first brought the plant from Virginia to Europe in 1614 as a botanical curiosity.
Most of the strains, however, came to Britain during the next century as stowaways in cargo ships carrying cotton. As cotton is light, soil was used as ballast. The ballast was dumped on reaching port, and with it stray seeds of evening primrose. Even today there are areas around the major ports, such as Liverpool, where evening primrose plants – descendants of the cotton ballast – grow in profusion.
In Europe, the evening primrose became known as ‘King’s Cure All’ by those who knew its almost magical medicinal properties. For centuries, however, the evening primrose was left to straggle along without anyone but a few specialist herbalists taking much notice. It wasn’t until this century that scientists began to look at the plant for its industrial potential in such things as paint.
In 1917 a German scientist called Unger examined the plant, and found that the seeds contained 15% oil, which was extractable with light petroleum. In 1919 the Archives of Pharmacology published a paper by Heiduschka and Luft who were the first to do a detailed analysis of the oil. They extracted 14% oil with ether, and apart from the normal oleic and linoleic acids, found a new fatty acid, which they named gammalinolenic acid (y-linolenic acid). In 1927, three German scientists repeated the Heiduschka and Luft test, and came up with a more detailed analysis of the chemical structure of this gammalinolenic acid (GLA).
Twenty-two years later Dr J.P. Riley, a British biochemist in the Department of Industrial Chemistry at Liverpool University, came across the German papers on evening primrose oil and decided to analyze the oil for himself, but this time using modern techniques. So Dr Riley set off for the sand hills near Southport in Merseyside and picked a bunch or two of evening primrose plants. He dried the plants, separated the seeds, and extracted the oil. To his great satisfaction, he found for himself the unique gammalinolenic acid.
It wasn’t until the 1960s, however, that British scientists began investigating the oil for its possible health uses. The first experiment was on rats. The aim of this experiment was to compare the biological activity of the commonly-found linoleic acid with the rare gammalinolenic acid.
The rats were put on a diet lacking in essential fatty acids, and after a few weeks they developed loss of hair and skin problems. They were then divided into two groups. One group was fed linoleic acid and the other group was fed gammalinolenic acid. The results of this first experiment were remarkable. The rats in the GLA group recovered more rapidly than the other group, and there was evidence that the GLA was far more efficiently taken up by the cells of all the important tissues and organs of the body.