According to the World Health Organization (WHO), nowadays between 10 and 15% of couples have fertility issues and between 30 and 35% of the reasons for infertility can be found in the male partner. Therefore, improving semen quality is one of the main concerns amongst couples with reproduction issues.
Poor semen quality can be the result of hormonal or genetic abnormalities but in the majority of cases there is a multifaceted and unknown cause. Pathological conditions such as cryptorchidism, varicocele, inflammation episodes, infections in the genital tract, cancer, periods of fever or stress and toxic environmental factors such as contamination and smoking are amongst the multiple factors that have a negative impact on semen quality.
Tobacco is one of the agents that could have a negative impact on spermatogenesis and it is a cause of great concern nowadays. Around 37% of men of reproductive age are smokers and, according to the WHO, Europe is one of the regions with the largest number of smokers. The toxic substances in tobacco can affect spermatozoa development and capacity and have a negative impact on semen parameters. It is for this reason that a significant amount of research has been done over the last few years on the impact of this toxin on reproduction and, in particular, on semen quality in men.
A study that was recently published in a leading international magazine (Sharma et al., 2016) consisted of an extensive review in order to determine if smoking cigarettes affected semen parameters. A total of 20 pieces of work and 5,865 participants were reviewed. Exposure to tobacco is linked to a diminished sperm count, motility and morphology and it was observed that this link increased the heavier a smoker the person was, thus confirming the negative impact of tobacco on conventional semen parameters.
Whilst the exact mechanisms due to which tobacco damages the quality of male gametes are yet unknown, its consumption has been linked in men to abnormalities in levels of hormones such as oestrone and estradiol. As well as reducing sperm concentration and motility, recent studies suggest that the components in tobacco generate an increase in DNA fragmentation in the sperm head. An increase in sperm DNA damage could have a negative impact on the results obtained in assisted reproduction techniques. Some studies indicate that there is a link to a decrease in fertilisation rates and implantation, as well as an increase in embryo arrest and pregnancy loss.
It has also been demonstrated that in male smokers there is an increase in free radicals (oxidative stress) in tissue such as the testicle. This could also mean greater sperm DNA fragmentation and increased cell death.
If these factors are taken into account, avoiding exposure to toxins such as tobacco can help to improve semen quality, as well as undoubtedly contributing towards a better general state of health.