How much coffee or tea do you consume everyday? Since many of us buy Slurpee sized cups of coffee in the morning, you should break those down into units of 8 ounce cups. How about cans of soda and in particular colas? Might be a good idea to keep track of this for a moment, as a recent study of 2,554 young Danish man has suggested that excessive cola intake could lead to lower sperm counts.
For comparison, the average young Danish military recruit consumes about 1 cup of coffee and 1 can of soda daily. This is in addition to about a half of cup of tea and 2 small chocolate bars (why not, Danish chocolate is yummy). This intake was associated with normal semen quality. However, the semen quality of young Danish men who consume more than 2 liters (2.1 quarts) of fizzy colas daily had a 30% less ejaculated sperm than men who drank no colas.
Interestingly, although colas are a weak source of caffeine (ounce for ounce, colas have 65% of the caffeine in coffee) there were no strong correlations between any amount of caffeine intake (even up to 7 cups of coffee a day!) and semen quality in these men. So, it is not likely that caffeine is the issue.
So what is the issue among those men who drink colas in excess? Well, the same issue as those who drink almost anything in excess—they have unhealthier lifestyles than those who consume in moderation. More burgers, more smoking, more alcohol, and fatter.
So, does drinking cola make men infertile? I doubt it, as the average sperm counts in men from all different levels of cola intake in the study were all normal by established fertility standards. Plus, fertility was not actually studied in these men, only a single semen sample. And even a good man can have a bad day.
There is a deeper truth running through this though. And you have heard this from me before. To be the best that you can be reproductively (and in life), do all things in moderation and treat your body like a temple.