The effect of caffeine on sperm count and quality remains hotly debated. Some studies have shown no difference but again there are others that suggest some effect of excess caffeine intake.
In coming to a conclusion, it is good to look at studies which study large number of patients. The larger the numbers of patients, the more likely the results are to be correct. So when the recent study in the American Journal of Epidemiology entitled “Caffeine intake and semen quality in a population of 2,554 young Danish men” concluded that heavy intake of cola depressed sperm counts by approximately 30%, we have to look seriously at the results due to the large number of men followed up over an extended period of time (four years). Whether this is due to the high intake of caffeine or to some other ingredient in cola is not known.
There was no effect on mild to moderate drinkers of cola, so for those of us who enjoy an occassional cola drink, there seems to be little or no risk. However, like all good things in life, moderation is the key. Apart from cola, other sources of caffiene include tea, coffee and chocolate.