Hold The Cola, Please
It seems like the experts are always coming up with a new food or beverage we need to cut out of our diets. Now, a Danish study says that drinking a lot of cola may lower a man's sperm count. Professor Tina Kold Jensen and her research team at the Copenhagen-based Rigshopitalet's University Department of Growth and Reproduction discovered that men who drink a lot of cola and other caffeinated drinks have a reduced concentration of sperm as well as a reduction in overall sperm count. But the most significant effects were seen in those who imbibed a lot of cola drinks as opposed to other drinks that are heavy in caffeine, such as coffee or tea.
However, the findings may not be so clear-cut: Cola-drinkers were found to eat a great deal more junk or fast foods and fewer fruits and vegetables. That means that researchers don't know if the problem is the large amounts of cola drunk or other lifestyle problems such as overall unhealthy eating habits. "It's important to note that the men who drank a lot of cola were also different in many other ways", said Professor Kold Jensen.
The authors of this study enlisted 2,554 young Danish participants and collected semen samples from them between the years 2001-2005 in order to determine the effects of caffeine on sperm production. The collection was made possible through the examinations held to assess the fitness of young Danes before they enter military service. Those men who contributed sperm samples also completed a questionnaire relating to their dietary and lifestyle habits. In the questionnaire were questions relating to the sources and amounts of caffeine consumed by the subjects.
A low to moderate intake of caffeine or cola did not have any effect on the quality of a given semen sample, but those who drank more than 7 liters of cola each week had almost 30% fewer sperm than those who abstained from cola-drinking. The scientists felt that this sperm reduction was probably not due to the caffeine found in cola, since a concomitant sperm reduction was not seen in those who refrained from drinking cola but instead drank similar amounts of tea or coffee. Coffee and tea have higher levels of caffeine than the same amounts of cola. These research findings were published by the American Journal of Epidemiology.
While the authors of the report don't know whether the reduced sperm quality was due to specific ingredients in cola other than caffeine, an unhealthy lifestyle, or several factors acting in tandem, they felt it impossible to, "… exclude the possibility of a threshold above which cola, and possibly caffeine, negatively affects semen quality."
Up until this time, studies that have examined the effects of caffeine on male fertility have produced varying results. Kold Jensen explains that the selection of participants for the earlier studies were chosen because they were already infertile or because they were about to undergo vasectomy surgery. In the current study however, sperm levels were still within normal levels according to the World Health Organization's standards. The Danish researchers believe that diminished sperm quality due to cola intake may be at least a partial or potential cause for some cases of infertility.