愛思唯爾期刊《營養學研究》（Nutrition Research）最近刊登了加拿大艾伯塔大學的一份最新研究，研究發現，經常飲用咖啡的婦女和偶爾飲用咖啡的女性獲得咖啡因提神效果是一樣的，同時經常飲用咖啡的婦女其心率以及血壓會有所偏高。
咖啡是當今世界上消費量最大的一種飲料，咖啡因是咖啡中的一種較為柔和的興奮劑，它可以提高人體的靈敏度、注意力、加速人體的新陳代謝，改善人體的精神狀態和體能。目前，人類在大約60種植物種發現了咖啡因，其中最為人知的便是茶和咖啡。在最新研究中，科學家對年齡範圍在18到37歲之間的攝取咖啡量顯著不同的兩種類型婦女進行了研究，其中一組接受研究婦女每天都飲用咖啡，而另外一組則偶爾飲用咖啡。研究人員分別對兩組婦女的心率、血壓、警覺能力等方面進行了研究。在食用早餐後，接受調查的婦女飲用了一杯咖啡，裡面大概含有大約140毫克的咖啡因。結果發現，經常飲用和偶爾飲用咖啡的女性獲得咖啡因「提神效果」是一樣的。這可能與咖啡因的刺激作用非常短暫有關，同時經常飲用咖啡的婦女其心率以及血壓會有所偏高。
研究人員認為，咖啡因能刺激中樞神經、胰臟、心臟和腦，可能導致血壓升高、心跳加速。研究人員認為，飲用咖啡還是會增加患心臟病、高血壓的危險性，所以對於患有高血壓或者體內血壓稍高的女性，還是應該減少日常咖啡因的攝取量。（生物谷Bioon.com）
生物谷推薦原始出處：
Nutrition Research，doi:10.1016/j.nutres.2008.06.003，Michael D. Kennedy, Megan K. Hudson
The cumulative effect of coffee and a mental stress task on heart rate, blood pressure, and mental alertness is similar in caffeine-na?ve and caffeine-habituated females
Michael D. Kennedy, , Ashley V. Gallowaya, Leanne J. Dickau and Megan K. Hudson
Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Alberta, E-488 Van Vliet Centre, Canada T6G 2H9
Abstract
Most North American workers drink coffee throughout their workday, although the cumulative effect of job stress and coffee is not well known. Research has shown that coffee affects the cardiovascular system and mental alertness primarily through the active ingredient caffeine; however, the dose of caffeine used in these studies is greater than a normal cup of coffee. In addition, these changes have been mostly determined in male caffeine-habituated consumers. Therefore, this study examined the effect of a normal cup of coffee on the cardiovascular and mental alertness response both before and after a mental stress task in 10 caffeine-na?ve (23 ± 5.0 years) and 10 caffeine-habituated (25 ± 6 years) females. Blood pressure, heart rate, and mental alertness were taken at baseline (before coffee), 50 minutes after finishing coffee and immediately after a 9-minute mental stress task. The volume of coffee ingested for a 15-minute period was 350 mL (12 oz), which is equivalent to 140 mg of caffeine. The combined effect of coffee and mental stress significantly decreased diastolic blood pressure (Δ8 mm Hg) and increased heart rate (Δ6 beats per minute) and mental alertness (Δ67.3%) in caffeine-na?ve and caffeine-habituated females, whereas systolic blood pressure (Δ10.3 mm Hg) only increased in the caffeine-na?ve participants. Our results indicate that a normal cup of coffee can effect changes in blood pressure and mental alertness and that mental stress may alter the magnitude of change; however, the transient increase in systolic blood pressure after drinking coffee in caffeine-na?ve participants requires further investigation.