If you are one of the estimated 40 million Americans plagued with allergies, asthma, atopic eczema or hay fever you may need to probe the root cause of your ailment.

Medically, these dissimilar disorders may actually be linked to one another by what is called "atopic illness," brought about by a lack of certain essential blood ingredients needed by the body to synthesize prostaglandins (PGs).

What are prostaglandins? Cellular molecules of unsaturated fatty acids which, over the short term, act like hormones in helping to regulate basic body processes, such as in controlling blood pressure or smooth muscle contraction. PGE1, one particular prostaglandin, contributes to dilating blood vessels, inhibiting blood clotting, reducing inflammation and, among other significant functions, lowering cholesterol.

Some of us have difficulty synthesizing prostaglandins

It is difficult for some of us to synthesize these life-promoting prostaglandins inasmuch as we don't take in enough essential fatty acids (EFAs) to supply the raw materials. (The World Health Organization recommends that adults take three percent of their total calories as EFAs and that lactating women and children take in five percent of their total calories as EFAs.)

Can we derive enough EFAs from the usual polyunsaturates, like vegetable oils? Not always, because all polyunsaturates are not biologically active. For example, vegetable oils are rich in linoleic acid -- an essential raw material for prostaglandins -- but coconut and palm oils are not. Further, vegetable oils, as a result of the processing for cooking fats and margarines, often lose their EFA effectiveness.

Even with a high enough intake of EFAs and linoleic acid, there is not always full assurance that these fatty acids will go through the proper biochemical conversions to become prostaglandins. Linoleic acid must first be translated into gammalinolenic acid (GLA) and, finally, into dihomo-gamma-linolenic acid (DGLA).

Breast-feeding infants can get GLA, DGLA and certain PGs ready-made from their mother's milk. The rest of us obtain it through the metabolism of ingested linoleic acid. Females convert this acid into GLA far more effectively than do males. Therefore, men require a greater linoleic acid intake.

Evening primrose oil supplements can help you overcome biological complexities

Conversion was a complex problem to males, and even to some females, until a scientific experiment revealed that it needn't be, inasmuch as evening primrose oil contains eight to nine percent GLA and more than 70 percent of cis-linoleic acid, the EFA-active form. Finally, there is a food supplement which detours a towering biochemical obstacle and gives us the same advantage enjoyed by nursing infants: getting prostaglandin precursors and some PGs directly.

If you wonder where evening primrose oil has been all your life, wonder no more. It has been here for ages, but not fully understood or appreciated by large populations until recently.

For centuries, native Americans pressed the oil from the seeds of the evening primrose, a beautiful, yellow wildflower which blooms, primarily on the Eastern seaboard, and dies in a single evening. Native Americans cured skin problems and wounds by applying evening primrose oil and took it by mouth to deal with asthma.

Those rugged individuals who, in the 17th century, braved stormy seas to sail to the "new land" from England, found evening primrose oil so healing that they shipped plants back home, where the oil of this flower healed an unbelievable number of ailments and, for this reason, soon became known as "The King's Cure-All." Not content with offsprings of the plants originally shipped to England, Agricultural Holdings, Ltd., a British seed company, searched world-wide from 1965 to 1987 and found more than 1,000 kinds of evening primrose, from which they developed plants with the richest yield of the highest quality oil.

Hundreds of studies exist on EPO

Excited about the great possibilities of evening primrose oil, biochemists produced hundreds of studies on this subject, making millions of us aware of the tremendous health possibilities within the tiny seeds of the evening primrose flower.

In its unparalleled ability to provide PG precursors, evening primrose oil has been found clinically valuable in helping or managing a wide span of medical problems: rheumatoid arthritis, cardiovascular conditions, premenstrual syndrome (PMS), breast pain, obesity, brittle nails, hair loss, skin diseases and allergies.

Arthritis. Relative to arthritis, Dr. Jill Belch, of the Department of Rheumatology at Glasgow University Medical School, carried out a major double-blind study of those suffering with rheumatoid arthritis. Some of the volunteers took only evening primrose oil, while others took a combination of evening primrose oil and eicosapentaenoic acid, an essential fatty acid from fish oil.

Ninety-four percent of the patients ingesting only evening primrose oil reported the disappearance of pain and inflammation, while 100 percent of those on evening primrose oil and eicosapentaenoic acid were remarkably improved. Consequently, all volunteers were able to stop taking non-steroidal, anti-inflammatory medications. Of the patients taking placebo capsules, 67 percent reported feeling no better or even worse.

Blood-related diseases. Several studies involving animals and human beings show that evening primrose oil may lower the risk of heart attacks, inasmuch as its high content of EFAs keeps blood platelets from sticking together and forming circulation-blocking, eventually fatalistic, clots. This oil also helps to lower blood pressure and cholesterol levels.

PMS. Much research reveals that evening primrose oil helps many women cope with premenstrual syndrome (PMS), a disorder with many painful symptoms: abdominal bloating, fluid retention, headaches, irritability, mood disorders, such as depression, irritability, weeping and occasional cases of uncontrollable rage, painful breasts, pelvic congestion and swollen ankles.

Several American clinicians have related unusual success in controlling PMS -- among them, Ann Nazzaro, Ph.D., a practicing psychologist in Northampton, Mass., and Donald Lombard, M.D., a PMS specialist.

Most of the women who reported "lives, jobs and families" disrupted each month by PMS returned to normal existence after evening primrose oil supplementation.

Magic? Not at all, states Nazzaro. "There's nothing magical about evening primrose oil," she says. "It simply corrects a chemical imbalance."

At one of the world's largest PMS clinics, St. Thomas Hospital in London, M.G. Brush, M.D., administered evening primrose oil to 70 women who had failed to get relief from one to two other attempted treatments.

But two 500-mg capsules three times daily provided total relief from PMS symptoms in 67 percent of the women treated. Twenty-two percent gained partial relief. The researchers were gratified that 89 percent of treatment-resistant women experienced partial to total relief.

Obesity. Over and above its positive influence on PMS, evening primrose oil has helped some struggling with obesity lose weight. Among those who weighed over 10 percent of their ideal weight, 50 percent lost weight without a dietary change after taking this supplement, claiming they experienced a reduced desire for food.

However, subjects who were within 10 percent of ideal body weight showed no reduction of extra weight from taking evening primrose oil.

Skin, hair and nail health. Essential fatty acids in evening primrose oil are also crucial to good health and beauty of skin, hair and nails. Individuals deficient in EFAs -- or if the EFAs can't be translated into GLA -- often show skin lesions, eczema, ichthyosis (fish skin) and hair loss, as well as brittle, cracking fingernails.

A double-blind, placebo-controlled study at the University of Bristol in England revealed that evening primrose oil brought about modest but significant improvement of eczema in adults and children.

Actually, the oil has proved effective in dealing with atopic disorders mentioned at the beginning of this article -- all of which are seemingly unrelated: allergies, asthma, eczema and hay fever. Evening primrose oil is important to those with atopic problems, because, with it, they can get the vitally-needed GLA, ready-made, eliminating their difficulty in metabolizing EFAs, says dermatologist Steven Wright, M.D., of the British Royal Infirmary.