Laboratory of Nutrition, Exercise and Health (LaNES), School of Medicine, Federal University of Uberlandia (UFU), Uberlandia, Minas Gerais, Brazil.
Laboratory of Nutrition, Exercise and Health (LaNES), School of Medicine, Federal University of Uberlandia (UFU), Uberlandia, Minas Gerais, Brazil.
Clin Nutr. 2024 Jun;43(6):1584-1592. doi: 10.1016/j.clnu.2024.05.004. Epub 2024 May 7.
Elevated levels of reactive oxygen species may contribute to the gradual decline in muscle strength over time. Although caffeine and its metabolites have antioxidant properties that can mitigate oxidative stress, the association of caffeine and its metabolites with muscle strength remains unknown.
To investigate whether caffeine metabolites in urine are associated with muscle strength in young and older adults.
A cross-sectional study was conducted with 1145 individuals aged over 20 years (n = 801 < 60 years and n = 344 ≥ 60 years) from the National Health and Nutrition Examination Survey (NHANES) 2011-2012. Muscle strength was assessed using a handgrip dynamometer, and combined grip strength was determined by summing the highest value from each hand. Caffeine and its metabolites in urine were quantified using ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (1-methyluric acid, 3-methyluric acid, 7-methyluric acid, 1,3-dimethyluric acid, 1,7-dimethyluric acid, 3,7-dimethyluric acid, 1,3,7-trimethyluric acid, 1-methylxanthine, 3-methylxanthine, 7-methylxanthine, 1,3-dimethylxanthine, 1,7-dimethylxanthine, 3,7-dimethylxanthine, 1,3,7-trimethylxanthine, 5-acetylamino-6-amino-3-methyluracil). Linear regression analyses were performed to determine the association of caffeine and its metabolites with muscle strength in young and older adults, adjusting for confounders.
Positive associations between muscle strength and levels of 7-methyluric acid (β = 0.029; p = 0.021), 1,3-dimethyluric acid (β = 0.008; p = 0.004), 3,7-dimethyluric acid (β = 0.645; p = 0.012), 3-methylxanthine (β = 0.020; p = 0.002), 7-methylxanthine (β = 0.020; p = 0.006), 1,3-dimethylxanthine (theophylline) (β = 0.030; p = 0.004) and 3,7-dimethylxanthine (theobromine) (β = 0.035; p = 0.029) were observed in older adults. In contrast, no such associations were noted in young adults.
Our study indicates a positive association between certain caffeine metabolites in urine and muscle strength in older adults, but not in younger individuals. These findings indicate that specific caffeine metabolites may contribute to an antioxidant role especially in older adults.
活性氧（reactive oxygen species，ROS）水平升高可能导致肌肉力量随时间逐渐下降。虽然咖啡因及其代谢物具有抗氧化特性，可减轻氧化应激，但咖啡因及其代谢物与肌肉力量的关系仍不清楚。
探讨尿液中的咖啡因代谢物是否与年轻和老年成年人的肌肉力量有关。
这是一项横断面研究，纳入了来自国家健康和营养检查调查（National Health and Nutrition Examination Survey，NHANES）2011-2012 年的 1145 名年龄在 20 岁及以上的个体（n=801<60 岁，n=344≥60 岁）。使用握力计评估肌肉力量，通过将每只手的最高值相加来确定总的握力。使用超高效液相色谱-电喷雾串联质谱法（ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry，UPLC-ESI-MS/MS）定量检测尿液中的咖啡因及其代谢物（1-甲基尿酸、3-甲基尿酸、7-甲基尿酸、1,3-二甲基尿酸、1,7-二甲基尿酸、3,7-二甲基尿酸、1,3,7-三甲基尿酸、1-甲基黄嘌呤、3-甲基黄嘌呤、7-甲基黄嘌呤、1,3-二甲基黄嘌呤、1,7-二甲基黄嘌呤、3,7-二甲基黄嘌呤、1,3,7-三甲基黄嘌呤、5-乙酰氨基-6-氨基-3-甲基尿嘧啶）。采用线性回归分析，在调整混杂因素后，评估咖啡因及其代谢物与年轻和老年成年人肌肉力量的关系。
在老年成年人中，肌肉力量与 7-甲基尿酸（β=0.029；p=0.021）、1,3-二甲基尿酸（β=0.008；p=0.004）、3,7-二甲基尿酸（β=0.645；p=0.012）、3-甲基黄嘌呤（β=0.020；p=0.002）、7-甲基黄嘌呤（β=0.020；p=0.006）、1,3-二甲基黄嘌呤（茶碱）（β=0.030；p=0.004）和 3,7-二甲基黄嘌呤（可可碱）（β=0.035；p=0.029）呈正相关。而在年轻成年人中，未观察到这些关联。
本研究表明，尿液中某些咖啡因代谢物与老年成年人的肌肉力量呈正相关，但与年轻个体无关。这些发现表明，特定的咖啡因代谢物可能发挥抗氧化作用，尤其是在老年成年人中。
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