New York: The sperm of men who smoke has a greater extent of DNA damage than that of non-smokers, says a new study that points to harmful effects of smoking on male fertility. Male infertility accounts for about 30 to 50 percent of all infertility cases, and infertile men tend to have high levels of damage to the sperm DNA. "More and more studies are demonstrating a harmful effect of smoking on male fertility,” senior author of the study Ricardo Pimenta Bertolla from Sao Paulo Federal University in Brazil. "Our results point in the direction of important semen alterations: Semen of smokers presents an inflammatory nature, associated with decreased capacity of sperm to achieve fertilisation and generate a healthy pregnancy," Pimenta Bertolla noted. The study involved 20 nonsmoking men and 20 men who smoked. Researchers also assessed 422 proteins in the participants' sperm. The analysis revealed that one protein was absent, 27 proteins were underrepresented, and six proteins were over-represented in smokers. Analyses of these proteins suggest that cigarette smoking may promote an inflammatory response in the male reproductive tract. The study was published in the journal BJU International. "It is especially noteworthy that, in our study, sperm DNA fragmentation was increased. Other studies have proposed this to be a potentially pro-mutagenic effect, which is to say that sperm with altered DNA may lead to health problems in the offspring," Pimenta Bertolla explained.