Smoking is discouraged for men with infertility. However, until this year, no conclusive evidence has been found to demonstrate exactly how smoking diminishes male fertility.
Studies Have Not Definitively Proven that Smoking Causes Male Infertility
Dr. Mohamed E. Hammadeh, head of the reproductive laboratory at the University of the Saarland in Saar, Germany, states that cigarettes may contain up to 4,000 chemical substances, at least 40 of which are known to be carcinogens or mutagens.
Mutagens are molecular substances that can harm otherwise healthy cells. However, according to Hammadeh, until now, no molecule has been discovered in tobacco that specifically harms male sperm; nor has a gene been identified that causes infertility in males.
2011 Study on the Effect of Smoking in Men with Fertility Issues
A recent study by Hussein A (2011) focused on 100 males with fertility issues. Of the subjects, 50 were smokers with an average age of 37 and 50 were non-smokers with an average age of 39. Results of the study showed statistically significant harm to certain characteristics of sperm. The study demonstrated that the sperm of the smokers were affected by in the following ways:
- The level of abnormal sperm was higher.
- The average sperm count was lower.
- The percentages of sperm motility were lower.
The most significant impact of smoking was on sperm motility.
2011 Study on the Impact of Smoking on Sperm
Another 2011 study of smoking and male infertility was conducted in Iran (Aghamohammadi A). No significant differences in the quality, volume or motility of sperm were found among males who smoked and those who did not.
- However, this study was of male partners of infertile couples, some of whom may have not been the infertile partner. Moreover, there is no mention of the age of the men, while Hussein’s study specifies infertile males with an average age of 37.
- The deleterious effects of smoking on many aspects of health normally do not appear in younger persons. This lends more credence to Hussein's study, in which the average subject was 37 years old.
A Breakthrough in the Genetic Link to Male Infertility
Helen Briggs, health editor of BBC News, announced that a new study by Dr. Edward Hollox of the University of Leicester provides exciting news about understanding male infertility at the molecular level. Hollox’s study reveals that the gene (DEFB126) causes infertility in men. When this particular gene is malformed, male fertility is compromised in the following way:
- This gene makes a protein that normally clings to sperm and helps them move easily to the female egg.
- When the gene is defective, sperm appear normal, but have great difficulty moving through the mucus that provides the environment necessary for fertilization.
The author of the study stated that this discovery identifies the cause of male infertility at the molecular level. Smoking is a known mutagenic substance that can harm healthy genes.
- Smoking could cause a healthy DEFB126 gene within a cell to mutate and become damaged as a man ages.
- Hussein’s study supports this possibility. He concluded in his study that smoking caused the most harm to motility of sperm.
Another Discovery at the Molecular Level
The second study is that of Dr. Mohamed E. Hammadeh, mentioned above. Hammadeh's team discovered that males who are heavy smokers have a significant drop in a protein, identified as protamines that are vital to the development of healthy sperm.
- Hammadeh’s study included 53 heavy smokers and 63 non-smokers.
- Results indicated that the smokers had levels of protamines that were 14% less than those of non-smokers.
By identifying the role of protamines, it can now be demonstrated how damage can be caused to sperm at the molecular level.
Smoking and Male Infertility
For decades, studies on smoking and male infertility have had conflicting results. Most importantly, past studies have not been able to identify how smoking adversely affects male fertility. New discoveries at the molecular level are showing how smoking can harm a gene critical to male fertility and reduce the levels of proteins that are essential for healthy sperm.
References:
Aghamohammadi A, Zafari M, “The impact of cigarette smoking on sperm parameters: A crosssectional study,” 2011 International Conference on Environmental, Biomedical and Biotechnology, IPCBEE, vol.16, © (2011)IACSIT Press, Singapore.
Hammadeh m, et al., “Protamine contents and P1/P2 ratio in human spermatozoa from smokers and non-smokers,” Hum Reprod, November 2010, Vol 25, Issue 11.
Hussein A et al., “Effect of Tobacco Smoking on Semen Quality in Men with Subfertility, Uro Today Int J, 2011 Feb 4.
Tollner TL et al., “A Common Mutation in the Defensin DEFB126 Causes Impaired Sperm Function and Subfertility,” Sci Transl Med 20 July 2011: Vol. 3, Issue 92.
Disclaimer: The information contained in this article is for educational purposes only and should not be used for diagnosis or to guide treatment without the opinion of a health professional. Any reader who is concerned about his or her health should contact a doctor for advice.
