Men considering fatherhood should steer away from nicotine - and not only in cigarettes, but nicotine-replacement products, such as gum or patches should also be avoided.
This is according to new research by the University of Stellenbosch revealing that nicotine harms sperm viability. The preliminary results of the new study were presented at a conference of the Physiology Society of South Africa at Stellenbosch University yesterday [Tuesday].
"We looked at the effects of nicotine on the male reproductive system," said the study leader Johann Maartens, a post-graduate student from the university's Department of Biomedical Sciences. The two-pronged study tested the effects of nicotine on sperm in a laboratory setting (in vitro), as well as in the human body (in vivo).
The laboratory study found that in both humans and rats, exposure to nicotine decreased the overall viability of sperm by between five and 15 percent. The sperm quality was assessed by testing the sperm cells' ability to swim (motility), the amount of live and dead cells (viability), the cells' ability to fuse with the female egg (acrosome capacitation status) as well as DNA fragmentation (a process associated with cell suicide).
"We don't know exactly why nicotine is bad for the male reproductive system, but we suspect it is due to the production of free radicals, particularly reactive oxygen species (a specific type of free radical)," explained Maartens. "We think nicotine causes higher levels of reactive oxygen species to be produced which in turn harms tissue."
Low levels of reactive oxygen species occur naturally in the body and are observed in certain bodily processes, but increased levels, such as that caused by nicotine, leads to oxidative stress which is harmful to the body.
For the in-vitro study they exposed sperm from 12 human donors as well as rat sperm in a laboratory setting to similar amounts of nicotine that a regular smoker would absorb. They found that sperm viability decreased with an increase in the level of nicotine exposure. Sperm viability decreased between five and 15 percent when exposed to amounts of nicotine similar to that which light, average and heavy smokers take in daily.
The second, in-vivo stage of the study is currently underway and researchers are looking at the effects of nicotine exposure on the reproductive systems of male rats, as well as the effects that nicotine exposure will have on male rats whose mothers were exposed to tobacco smoke during pregnancy. The results for the in-vivo study are expected to be available next year.