Evening primrose oil is rich in gamma-linolenic acid. This is an essential fatty acid, one of the n-3 essential fatty acids the body needs to make the hormones that "put the brakes" on inflammation. The value of creating anti-inflammatory hormones in the cervical mucus is obvious. Sperm that are not attacked as if they were bacteria, foreign objects, or allergens are far more likely to reach the uterus to fertilize the egg. Women who take Evening Primrose Oil often see a dramatic change in their cervical mucus. Mucus that is brown, thin, and dry becomes white, thick, and stretchable. The "stretch"' of the cervical mucus is a very important characteristic. The viscosity of the mucus helps propel the sperm forward. When the mucus is unusually dry, sperm can get literally trapped in the mucus and never reach their destination at the opening of the ovary. When the mucus is filled with the inflammatory hormones known as cytokines, sperm may be destroyed in the mucus itself, making conception impossible.
Evening Primrose Oil, however, can be as destructive as it is helpful. It is absolutely essential that women only take it during the first half of their menstrual cycles, between menstruation and ovulation. The reason for this restriction is that evening primrose oil sometimes stimulates uterine contraction. If the uterus is stimulated after the egg is fertilized, it may not be implanted in the endometrium and spontaneous abortion may occur just a day or two after conception. The effects of evening primrose oil are not enhanced by taking a larger dose. From 1,000 mg to 2,000 mg a day is enough. However, the effects of this herbal supplement may be increased by avoiding sugar and foods containing a fatty acid known as arachidonic acid, namely beef, lunchmeat, and eggs. Sugar and arachidonic acid increase the production of the pro-inflammatory hormones the anti-inflammatory hormones are intended to balance. Evening primrose oil is generally safe when used at the right time in a woman's menstrual cycle. Since a few case reports indicate interaction with seizure medications, however, women who have seizure disorders should not take it.