Preparations with antioxidants, including some vitamins, can improve male fertility, reports the Cochrane Library website. The Proceedings of the National Academy of Science reports at the same time about their harmful effect on female fertility.
Researchers from the University of Auckland in New Zealand analyzed the results of 34 studies involving a total of 2.876 couples using assisted reproductive techniques, including in vitro fertilization. Most of the men taking part in them showed insufficient number and motility of sperm, which may cause problems with the natural conception of a child.
Statistics show that such fertility problems concern an increasing number of men. Scientists speculate that one of the factors responsible for reducing the number and motility of sperm may be the overproduction of the so-called free radicals – very active molecules that damage valuable cell components. They are formed in the body during natural metabolic changes. In healthy people, the mechanisms eliminating excess free radicals work properly, but under the influence of chronic stress or in states of weakness, they may fail. It is believed that an excess of these molecules can accelerate aging and the development of cancer. Sperm are very susceptible to their effects.
Therefore, researchers suspect that compounds known as antioxidants that neutralize free radicals could improve fertility in some men. These include, among others some vitamins like C and E and minerals.
The men participating in the study used oral preparations with various types of antioxidants – vitamin E, L-carnitine, zinc and magnesium.
The analysis showed that women whose partners took these drugs had a 4 times greater chance of getting pregnant and almost 5 times greater chance of having a baby, compared to women whose partners did not take these drugs.
The researchers emphasize, however, that children were born in only the three analyzed studies and there were 20 of them in total, while 96 women out of 15 studies became pregnant.
No side effects related to the use of these preparations were observed.
Due to insufficient data, scientists could not compare the effectiveness of different types of antioxidants.
According to the lead researcher, Marian Showell, these results suggest that men using assisted reproductive methods could increase their partner’s chances of becoming pregnant if they started using antioxidants.
The researcher also made a reservation that more studies would be needed to confirm this.
Another face of these compounds has been revealed by the research of prof. Navy Dekel from the Weizmann Institute of Science in Rehovot, Israel. They show that they can reduce female fertility.
In experiments, mice were injected with antioxidants into the ovaries, which were stimulated to ovulate with the aid of luteinizing hormone (LH).
It turned out that ovulation was much less efficient than normal in the presence of these compounds – significantly fewer eggs were released from the ovaries ready for fertilization. Moreover, antioxidants also inhibited the activity of genes that play an important role in the ovulation process and which under physiological conditions are activated by the luteinizing hormone.
Further tests showed that free radicals could stimulate ovulation similar to LH. According to the authors of the study, this means that these molecules, produced in response to the release of luteinizing hormone from the pituitary gland of the brain, are an activator of the ovulation process.
As prof. Dekel, these studies suggest that antioxidants can reduce female fertility, and women should take them with caution.
According to the researcher, this discovery may help not only women who have problems with getting pregnant. It also shows that some antioxidants can be good contraceptives and safer than hormonal methods.
Prof. Dekel reminds that dietary supplements containing antioxidants are readily available over the counter, not only in pharmacies. Besides, these substances are added to food, beverages and cosmetics. However, there is still no complete data on the effects of their action on the human body.
Theoretically, they should slow down the aging process and prevent the development of various diseases, because they eliminate harmful free radicals. Recently, however, a growing body of research proves that free radicals can play an important role in many physiological processes. Therefore, healthy people who get enough antioxidants along with a varied diet, rich in, among others, in vegetables and fruits, they should rather not use any additional preparations with these compounds.
In the future, prof. Dekel and her colleagues are planning further experiments in mice that will allow us to assess the effect of antioxidants delivered by food on the ovulation process. They also want to see if women taking antioxidant preparations have more problems with getting pregnant. (PAP)