A new study by researchers in Sweden reveals that smoking can lead to men losing their Y chromosomes, resulting in decreased sperm counts.
The research, which was published in the Science journal, is another entry to the long list of studies that detail the negative effects of smoking.
The study shows that male smokers are three times more likely to lose their Y chromosomes compared to non-smoking men.
The researchers believe that this loss of Y chromosomes could help in the explanation on why it is more likely for men to develop cancers that are connected with smoking compared to women.
"The strength of association between smoking and this mutation was a surprise," said Jan Dumanski, an Uppsala University professor and a co-author of the study.
Y chromosomes, only found in men, are one of the two types of sex chromosomes. Y chromosomes determine the male gender, and as such are capable of affecting factors such as the development testicles. Evolution has caused the chromosome to lose many of its original genes, with the remaining ones very important to the entire male body and not just to the reproductive system.
The team of researchers studied the data from over 6,000 male subjects, considering the information on their ages, cholesterol levels, exercise habits, lifestyle behavior, alcohol intake, education level, smoking habits, and many more.
The study revealed that the disappearance of the Y chromosome from a man's blood cells is three time more likely for those that are currently smoking, compared to men that have never tried smoking or those that have dropped the habit.
The good news for smokers, however, is that the loss of Y chromosomes is reversible, according to Dumanski, adding that smokers with fertility problems should quit smoking to restore their sperm count.
Dumanski also said that there was no discernible difference in the levels of Y chromosomes between non-smokers and those that quit smoking. The loss of the Y chromosomes appeared to be dependent on how much men smoke, not on whether men have smoked or not.
According to Dumanski, the results of the study can serve as additional motivation for smokers to drop the life-risking habit.
"Smoking is simply more dangerous for men. This finding may in part explain why men in general have a shorter life span than women," he said.
Dumanski, however, admitted that for chromosome and DNA damage to be considered a definite part of the harmful effects of smoking, more understanding regarding the ability of smoking to inflict such massive genetic damage must be made.
