Connection between increased cola intake and poorer semen quality

January 01, 0001

Connection between increased cola intake and poorer semen quality

The authors from Denmark examined the association between semen quality and caffeine intake among 2,554 young Danish men recruited when they were examined to determine their fitness for military service in 2001-2005. The men delivered a semen sample and answered a questionnaire including information about caffeine intake from various sources, from which total caffeine intake was calculated. Moderate caffeine and cola intakes (101-800 mg/day and less than or equal to 0.5-L bottles of cola/week) compared with low intake (less than or qual to 100 mg/day, no cola intake) were not associated with semen quality.

High cola (greater than 14 0.5-L bottles/week) and/or caffeine (greater than 800 mg/day) intake was associated with reduced sperm concentration and total sperm count, although only significant for cola. High-intake cola drinkers had an adjusted sperm concentration and total sperm count of 40 mill/mL and 121 mill, respectively, compared with 56 mill/mL and 181 mill in non-cola-drinkers, which could not be attributed to the caffeine they consumed because it was less than 140 mg/day.

The researchers concluded: " … the authors cannot exclude the possibility of a threshold above which cola, and possibly caffeine, negatively affects semen quality."

This association does not prove causation. Other factors related to less healthy lifestyle of these men may explain the findings."

For the full abstract, click here.

American Journal of Epidemiology 171(8):883-891, published online 25 March 2010
© The Author 2010
Caffeine Intake and Semen Quality in a Population of 2,554 Young Danish Men. Tina Kold Jensen, Shanna H. Swan, Niels E. Skakkebæk, Sanne Rasmussen and Niels Jørgensen. Correspondence to Tina Kold Jensen: [email protected]

Category: Y. Male Genital System, Breast. Keywords: caffeine, cola, fertility, reproductive medicine, semen analysis, questionnaire, association, journal watch.
Synopsis edited by Dr Stephen Wilkinson, Melbourne, Australia. Posted on Global Family Doctor 14 May 2010

Pearls are an independent product of the Cochrane primary care group and are meant for educational use and not to guide clinical care.