University Department of Growth and Reproduction, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen Ø, Denmark.
Am J Epidemiol. 2010 Apr 15;171(8):883-91. doi: 10.1093/aje/kwq007. Epub 2010 Mar 25.
The authors 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 < or =14 0.5-L bottles of cola/week) compared with low intake (< or =100 mg/day, no cola intake) were not associated with semen quality. High cola (>14 0.5-L bottles/week) and/or caffeine (>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 (95% confidence interval (CI): 32, 51) and 121 mill (95% CI: 92, 160), respectively, compared with 56 mill/mL (95% CI: 50, 64) and 181 mill (95% CI: 156, 210) in non-cola-drinkers, which could not be attributed to the caffeine they consumed because it was <140 mg/day. Therefore, the authors cannot exclude the possibility of a threshold above which cola, and possibly caffeine, negatively affects semen quality. Alternatively, the less healthy lifestyle of these men may explain these findings.
作者研究了 2554 名丹麦年轻男性的精液质量与咖啡因摄入之间的关系，这些男性在 2001-2005 年接受兵役体检时被招募。这些男性提供了一份精液样本，并回答了一份包括各种咖啡因来源摄入信息的问卷，由此计算出总咖啡因摄入量。与低摄入量（<100mg/天，无可乐摄入）相比，中等咖啡因和可乐摄入量（101-800mg/天和<或=14 0.5-L 瓶/周）与精液质量无关。高可乐（>14 0.5-L 瓶/周）和/或咖啡因（>800mg/天）摄入与精子浓度和总精子数减少相关，尽管仅可乐有显著意义。高摄入量可乐饮用者的精子浓度和总精子数分别为 40 毫/mL（95%置信区间（CI）：32，51）和 121 毫（95% CI：92，160），而不饮用可乐者分别为 56 毫/mL（95% CI：50，64）和 181 毫（95% CI：156，210），这不能归因于他们摄入的咖啡因<140mg/天。因此，作者不能排除可乐，以及可能的咖啡因，在超过一定阈值后对精液质量产生负面影响的可能性。或者，这些男性的生活方式不太健康，这可能解释了这些发现。
