High cola intake may cut sperm count, reports Danish study

Men who drink a few too many Diet Coke or some other cola-like beverages daily may have fewer sperm, according to a new study.

The study, published in the April 15, 2010 issue of American Journal of Epidemiology (1), had examined the semen quality of more than 2,500 young Danish men who had been recruited upon was evaluated for fitness and military service.

They found that those subjects who reported on a questionnaire that they consumed high amounts of caffeine (more than 800 mg per day) or high intakes of cola (more than 14 half-liter bottles per week) had reduced sperm concentration and total sperm count. On the other hand, the consumption of only moderate amounts of caffeine (less than 800 mg per day) or low amounts of cola (less than 14 half-liter bottles per week) were not associated with any similar effect on sperm concentration or count.

There was no association established between caffeine from tea or coffee and influence on sperm count.

The Copenhagen researchers of University of Denmark of Growth and Reproduction concluded that they “cannot exclude the possibility of a threshold above which cola, and possibly caffeine, negatively affects semen quality” (1).

They added, “Alternatively, the less healthy lifestyle of these men may explain these findings” (1).

Still, if you’re interested in maintaining your vitality (who isn’t?), it may be better to avoid the cola!

Caffeine and Semen Quality

There have been several studies that have investigated caffeine and a possible association with semen quality, which have led to conflicting results.

Previous to this study on high intakes of cola, there had been a pregnancy cohort in 2008 on more than 5,000 males that evaluated semen quality in association with prenatal coffee and caffeine exposure (2).

The study, also from Denmark, found that although high caffeine intake didn’t have any significant effect on semen quality, it did lead to increased testosterone concentrations (approximately 14 percent) in the men (2).

So, until more research is conducted, there’s still no need to give up on the coffee.


1. Jensen TK, Swan SH, Skakkebaek NE, Rasmussen S, Jørgensen N. Caffeine intake and semen quality in a population of 2,554 young Danish men. Am J Epidemiol. 2010 Apr 15;171(8):883-91. Epub 2010 Mar 25.

2. Ramlau-Hansen CH, Thulstrup AM, Bonde JP, Olsen J, Bech BH. Semen quality according to prenatal coffee and present caffeine exposure: two decades of follow-up of a pregnancy cohort. Hum Reprod. 2008 Dec;23(12):2799-805. Epub 2008 Aug 28.

Published by David Despain, MS, CFS

David is a science and health writer living on Long Island, New York. He's written for a variety of publications including Scientific American, Outside Online, the American Society for Nutrition's (ASN) Nutrition Notes Daily, and Institute of Food Technologists' (IFT) Food Technology magazine and Live! blog. He's also covered new findings reported at scientific meetings including Experimental Biology, AAAS, AOCS, CASW, Sigma Xi, IFT, and others on his personal blog "Evolving Health." David is also an active member of organizations including the National Association of Science Writers (NASW), the American Association for the Advancement of Science (AAAS), the American Society for Nutrition, the Institute of Food Technologists, and the National Audubon Society. David has a master's degree in human nutrition from the University of Bridgeport, and a bachelor's degree in English from University of Illinois at Springfield. He also earned his Certified Food Scientist credential from the Institute of Food Technologists.

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