Danish researchers have found a link between male infertility and excessive consumption of cola-flavoured soft drinks. The study, published in the American Journal of Epidemiology, was designed to look for sperm count differences according to caffeine consumption, but found surprising results among cola drinkers.

Researchers found that both subjects who consumed more than 7 litres of cola a week, and those who consumed more than 800mg of caffeine a day, had an overall reduced sperm concentration and lower total sperm count than control subjects.

However, the difference was only statistically significant for the cola drinkers, with both total sperm count and sperm concentration significantly lower than in the non-cola-drinking population. Because cola doesn’t contain an enormous amount of caffeine, researchers had to consider the possibility that something else in the cola, or in the behaviour of cola drinkers, was causing the problem

“We cannot exclude the possibility of a threshold above which cola (and possibly caffeine) negatively affects semen quality,” the researchers noted.

“Alternatively, a less healthy lifestyle among these men may explain the findings. Since cola consumption is high and has been increasing among young Danes, our findings, if confirmed, may be of public health concern.”

Subjects who drank moderate amounts of cola had no notable effects.

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