Cola lowers sperm count, study doesn’t show

Written by: Captain Skellett // April 7th, 2010 // Science at Home, Science Communication, Sex and Reproduction

The headline “Cola lowers sperm count, study shows” popped up on ninemsn recently. Usually I don’t pay much mind to ninemsn, but they had a grizzly story about a Russians who drowned a girl, then served her as meat with a side of potatoes to her friend. They plead guilty and said they had done it because they were drunk and hungry, but they HAD POTATOES! Once they drew me in with that story, I checked out the other headlines and stumbled across the cola article.

And I quote: “If you’re trying to have a baby, it might be a good idea to keep an eye on your partner’s cola intake, as a Danish researchers have found that big cola drinkers can have sperm counts up to 30 percent lower than normal.”

I have issues with the cola article.

The research paper is in the advance issue of the American Journal of Epidemiology, and you can read it here. They found that people with a high cola intake had lower sperm count. That doesn’t mean drinking lots of cola CAUSES low sperm count.

Towards the end it reads: “High-quantity consumers of cola or caffeine had an unhealthier lifestyle, which has previously been associated with poorer semen quality”. So is the low sperm count because of the cola or the lifestyle? The researchers considered the diet factor and wrote that it did not explain the correlation, but the report didn’t include any details on how they considered diet so it’s impossible to say if it was accurate.

High cola intake and low sperm count could both be caused by an unhealthy lifestyle. Other things that could cause them are discussed in the report, which reads: “High caffeine and cola consumption may also be related to in utero exposure to caffeine, working in a sedentary position, being less physical active, or being more stressed, variables that have previously been associated with poorer semen quality. Unfortunately, we did not obtain information about these factors.”

Any of these things or something else entirely could cause both high cola intake and low sperm count. Although drinking lots of cola can be correlated to having a lower sperm count, it damn sure doesn’t mean “cola lowers sperm count, study shows.” The study doesn’t show that at all, to me it doesn’t say anything that we didn’t already know.

Granted, ninemsn did write at the very bottom that the results couldn’t be separated from other lifestyle factors. Still, the article still reads like it’s big scary news. Going at it with an angle like “Ooh, don’t let your husbands drink cola, ladies” is just bad science. Walk the plank.

Captain Skellett

I be Captain Skellett. Me blog started in April 2009 when I was working full time and didn’t get a chance to talk science. Now I have changed jobs and talk science all the time, but that doesn’t stop me blogging. More About Captain Skellett   Google


5 Responses to “Cola lowers sperm count, study doesn’t show”

  1. Sarah says:

    These people obviously didn’t do year 8 science where you learn to eliminate all the other variables…

  2. kat says:

    also… so true.
    bum science makes me sad.

    on the other hand, i found a disorder called EXPLODING HEAD SYNDROME.

    luckily its not fatal.. lol…
    check it out!\
    hope you had a good easter, sorry we didnt catch up after all!

    Arr, that be amazing! Now THAT explains a shipmate of mine who was ever sitting bolt upright in his bunk and crying canon fire. “Loud crash at 3am? It may be your exploding head.” Epic.

  3. James says:

    I love that I am writing draft after draft of a manuscript and these guys publish something where they seemingly pull two variables out of a hat and then calculated a correlation. I could do that, but I choose to do real, accurate science instead.

    /climbs down from high horse

    Absolutely agreed, I think your high horse status is completely justified.

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