J Acad Nutr Diet. 2019 Jan;119(1):106-114. doi: 10.1016/j.jand.2018.08.152. Epub 2018 Nov 13.
Caffeine increases alertness when consumed in single servings of various products including coffee, tea, soft drinks, and energy drinks. Although not a nutrient, caffeine is consumed by 90% of the adult population in the United States.
This study examined the daily pattern of caffeine intake and its relationship to multiple demographic variables.
Data from the National Health and Nutrition Examination Survey (NHANES) 2007-2012 (adults aged 19+ years; n=16,173) were used to determine the time of day at which caffeine is consumed and demographic factors associated with intake. Regression analyses characterized factors associated with caffeine intake including sex, age, ethnicity, education, smoking status, physical activity, employment status, total work hours, alcohol, and energy intake.
Mean adult per capita caffeine intake was 169±4 mg/d (mean±standard error). Most caffeine (70%) was consumed before noon, often at breakfast, and intake decreased progressively over the day, with little consumed after 9:00 pm. Intake was associated with age, ethnicity, smoking status, total calorie intake, and work hours (P<0.01) but not physical activity, economic status, education level, or employment status. Variables with the largest associations with intake were, respectively, ethnicity and age. Non-Hispanic black individuals consumed the smallest amounts (80±2 mg/d), non-Hispanic white individuals consumed the greatest amounts (194±3 mg/d), and Asian individuals (126±7 mg/d) and Hispanic individuals consumed intermediate amounts (127±3 mg/d). Middle-aged individuals (aged 50 to 54 years) consumed more caffeine (211±6 mg/d) than younger (107±4 mg/d, aged 20 to 24 years) and older individuals (153±4 mg/d, aged 75 to 79 years).
Most caffeine is consumed in the morning, when alertness is lowest, and very little in the evening before sleep. Ethnicity and age were the variables most strongly associated with intake; work hours, occupation, energy and alcohol intake, and smoking were also associated with intake. Because caffeine increases alertness, it is not surprising that its pattern of consumption and factors associated with its intake vary from those of most other food constituents.
咖啡因存在于各种产品中，包括咖啡、茶、软饮料和能量饮料，单次摄入这些产品都能提高警觉性。虽然咖啡因不是营养物质，但美国 90%的成年人都有摄入咖啡因。
本研究检测了咖啡因的日常摄入模式及其与多种人口统计学变量的关系。
使用 2007-2012 年全国健康和营养调查（NHANES）的数据（年龄在 19 岁及以上的成年人；n=16173），确定了摄入咖啡因的时间以及与摄入相关的人口统计学因素。回归分析描述了与咖啡因摄入相关的因素，包括性别、年龄、种族、教育程度、吸烟状况、身体活动、就业状况、总工作时间、酒精和能量摄入。
成人平均人均咖啡因摄入量为 169±4mg/d（平均值±标准误差）。大多数咖啡因（70%）在中午前摄入，通常在早餐时摄入，并且随着一天的进行，摄入量逐渐减少，晚上 9 点后很少摄入。摄入量与年龄、种族、吸烟状况、总卡路里摄入和工作时间有关（P<0.01），但与身体活动、经济状况、教育程度或就业状况无关。与摄入量关联最大的变量分别是种族和年龄。非西班牙裔黑人摄入的咖啡因最少（80±2mg/d），非西班牙裔白种人摄入的咖啡因最多（194±3mg/d），亚洲人（126±7mg/d）和西班牙裔（127±3mg/d）摄入的咖啡因居中。中年个体（50 至 54 岁）的咖啡因摄入量（211±6mg/d）高于年轻个体（107±4mg/d，20 至 24 岁）和老年个体（153±4mg/d，75 至 79 岁）。
大多数咖啡因在早上摄入，此时警觉性最低，晚上在睡前摄入很少。种族和年龄是与摄入量最相关的变量；工作时间、职业、能量和酒精摄入以及吸烟也与摄入量有关。由于咖啡因能提高警觉性，因此它的消费模式及其与摄入量相关的因素与大多数其他食物成分不同也就不足为奇了。
