Herbal remedy found to reduce fertility in men
DOES IT WORK:Gossypol could be used as a male contraceptive pill
THE WORLD’S population continues to grow, especially in developing countries. Various approaches to family planning and contraception are being pursued.
One of the challenges has been finding ways to encourage men to take greater responsibility in this area. A herbal remedy called gossypol has attracted much interest as a male contraceptive pill.
While the ethical, social and political implications of contraception are significant, ongoing research has clarified some of the strengths and weaknesses of gossypol.
Gossypol is found in the roots, seeds and stems of the cotton plant. It is a natural insecticide which causes infertility in insects that feed on cotton plants.
After cotton is harvested, the seeds and other plant parts can be pressed into cottonseed cake. However, farmers noted that when this was fed to livestock, it sometimes causes infertility.
Chinese researchers found that in areas where crude cottonseed oil was commonly used, family sizes were much smaller. By the 1970s, gossypol had been identified as the active ingredient.
The Chinese government was hoping that gossypol would become a non-steroidal contraceptive that could be widely used to limit family sizes. Gossypol is now removed from commercial cottonseed oil and put in tablets.
In laboratory studies, gossypol has been shown to damage sperm and interfere with their mobility. In animals, gossypol has numerous effects that reduce the production of sperm.
These results led to several studies in China involving thousands of men which showed that sperm counts were reduced after about two months of taking gossypol.
However, individual men varied in the extent of this sperm reduction. On average, about 60 per cent of men taking gossypol achieve a low enough sperm count to be considered infertile.
This usually requires a higher dose for the first two months (10-20mg/day), followed by a maintenance dose of about half the initial amount.
While the Chinese research showed that gossypol works, it also revealed problems. Some men experienced fatigue, muscle weakness and even paralysis, which was connected to loss of potassium.
However, more recent research has suggested that these problems only affect men when they have low potassium levels before taking gossypol.
Some diuretics used to treat heart disease and high blood pressure eliminate potassium. Taking gossypol along with these drugs could lead to very low potassium levels and may require potassium supplementation.
One of the more serious problems found with gossypol is that up to 50 per cent of the men taking it do not recover fertility. Some studies have followed men for up to four-and-a-half years after they stopped taking gossypol and many have remained infertile.
The reasons for this are uncertain, but it may have to do with permanent damage to the tissues producing sperm.
In 1998, the World Health Organisation (WHO) concluded that the toxic effects and risk of permanent infertility made gossypol unsuitable as a male contraceptive. However, some research has continued, in particular in China, South America and Africa.
More recent studies have included men who wish to become permanently infertile. These have confirmed that gossypol is effective as a long-term contraceptive for about two-thirds of men.
Those who have adequate potassium intake do not experience as many other side effects.
However, considerable debate continues as to whether the benefits of using gossypol outweigh its risks. Most authorities agree with the WHO position of not recommending use of gossypol.
Further research is needed to determine if gossypol can be modified to resolve these problems. Gossypol highlights the fact that even when a herbal remedy is shown to be effective, its harmful effects may undermine its overall usefulness.
- Dónal OMathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University