Caffeine

撰文丨王聪 编辑丨王多鱼 排版丨水成文 如果需要在早上振作精神，抑或是需要熬夜完成一些工作，大多数人会选择喝一杯咖啡或是含有咖啡因的功能饮料。咖啡饮这种令人兴奋的化学物质的“夜猫子”效应，早已为人所知。 大量流行病学研究表明，夜猫子比早起的人更倾向于喝含咖啡因的饮料，动物和细胞实验也表明，咖啡因通过影响生物钟延长清醒时间。 而一项新研究意外地发现，在咖啡中添加糖或人工甜味剂，比咖啡本身更能扰乱生物钟，导致昼夜颠倒。 该研究于近期发表在了Nature 旗下期刊 npj Science of Food 上，论文题为：Sweetened caffeine drinking revealed behavioral rhythm independent of the central circadian clock in male mice 。 在这项研究中，研究团队旨在探索小鼠在饮用甜的咖啡因水溶液期间的一般行为特征。研究团队提供了几种饮用水，分别含有0.1%咖啡因、1%蔗糖、0.1%糖精、0.05%咖啡因+1%蔗糖、0.1%咖啡因+1%蔗糖。 饮用了咖啡因+甜味剂混合物（蔗糖或糖精）的小鼠经历了26-30小时的非常长的“自由运行”睡眠-觉醒周期，一些小鼠甚至从原本的夜间昼夜节律转变为白天昼夜节律。即使小鼠处于持续的黑暗中，这些影响也会继续发生。这表明了咖啡因-甜味剂效应独立于体内生物钟的中枢调节器（位于大脑下丘脑的视交叉上核）来发挥作用。这个中枢调节器本身通常受光和自然昼夜循环的控制，反过来，它又确保身体其他部位器官组织的生物钟同步。 研究团队表示，增加的糖或人工甜味剂并没有改变小鼠喝的咖啡因水的量，所以这种影响不可能只是因为喝了更多的咖啡因。而是因为咖啡因和甜味剂的结合。 研究人员认为，咖啡因和甜味剂的结合可能会在体内产生一种相互矛盾的信号，这可能是由多巴胺介导的。咖啡因和甜味剂都会激活大脑中的奖赏系统，导致多巴胺的释放。正是这种多巴胺的双重作用可能导致了长期活动节律的出现。 研究团队表示，接下来的目标是进一步探索咖啡因+甜味剂的作用与多巴胺可能存在的联系，并观察甜味剂对咖啡因的促进作用是否能在人类身上复制。虽然这项初步研究只观察了对小鼠的影响，但研究结果可能对我们理解含糖咖啡因如何影响人体健康有重要意义。 通常建议每天摄入咖啡因不要太多，或建议减少晚上或夜间摄入咖啡因，因为过量摄入咖啡因会导致睡眠质量下降和夜猫子倾向增强，而这会对身心健康产生一系列负面影响。而这项新研究表明，在咖啡因中添加甜味剂可能会进一步加剧负面影响。 研究团队还表示，如果你是想在早上更加精力充沛，或许可以考虑在喝咖啡时吃点甜食。 论文链接： https://www.nature.com/articles/s41538-024-00295-6 设置星标，不错过精彩推文 开放转载 欢迎转发到朋友圈和微信群  微信加群  为促进前沿研究的传播和交流，我们组建了多个专业交流群，长按下方二维码，即可添加小编微信进群，由于申请人数较多，添加微信时请备注：学校/专业/姓名，如果是PI/教授，还请注明。 点在看，传递你的品味

MONDAY, Dec. 23, 2024 -- Coffee provides a quick morning boost, but it might also protect the brain health of people with a common heart rhythm disorder . A study published recently in the Journal of the American Heart Association shows patients with atrial fibrillation who drank more than five cups of coffee a day performed better on an array of cognitive tests than those who drank little to no coffee. In fact, the brains of heavy coffee drinkers were nearly seven years younger in cognitive age compared to coffee teetotalers. “Many myths are around, but our study found no reason to discourage or forbid a patient with A-Fib from drinking coffee. Instead, say, ‘Enjoy, it may even be good for you!’” senior researcher Dr. Jürg Beer , a professor of medicine and hematology at the University of Zürich in Switzerland, said in an American Heart Association (AHA) news release. Atrial fibrillation is the most common heart rhythm disorder in adults, affecting more than 5 million people in the United States, according to the AHA. A-Fib occurs when the upper chambers of the heart -- the atria -- begin beating in a quivering and uncoordinated way. This allows blood to pool in the atria and potentially clot. A-Fib increases a person’s risk of stroke fivefold, as a blood clot can travel from the atria and block blood flow to the brain, according to the U.S. Centers for Disease Control and Prevention. Current American Heart Association guidelines say that abstaining from caffeine doesn’t benefit people with A-Fib, unless patients report that caffeine triggers or worsens their symptoms, researchers noted. Symptoms can include rapid heartbeat, dizziness, fatigue, shortness of breath and chest pain. “It is known that regular coffee consumption benefits cognitive performance among healthy people. The most frequent cardiac arrhythmia, atrial fibrillation, is known to independently increase the risk of dementia,” said lead researcher Dr. Massimo Barbagallo , a resident in the neuro intensive care unit at the University Hospital Zürich. “Thus, the question is whether coffee might offset the increased risk of cognitive impairment in people with A-Fib,” Barbagallo said. For the study, researchers recruited more than 2,400 people in Switzerland diagnosed with atrial fibrillation between 2014 and 2017. Participants completed several brain tests and reported how many cups of caffeinated coffee they drank during the last 12 months. Results showed that the more coffee a person drank, the better they performed on cognitive tests. “There was a very clear and consistent ‘dose-response’ association between drinking more coffee and doing better on several different sophisticated cognitive tests,” Beer said. Specifically, their scores were about 11% higher than people who drank little to no coffee, researchers found. Coffee also appeared to lower inflammation in A-Fib patients. Inflammatory markers were more than 20% lower in people drinking five cups daily than those drinking less than one cup a day. “Inflammatory markers decreased with higher coffee consumption, an association that remained after considering variables such as age, sex, body mass index, smoking status, physical activity and a history of stroke,” Beer said. It’s not quite clear why coffee might help brain health, researchers said. It could be due to caffeine or other active ingredients in coffee, like magnesium and niacin, or it might be due to coffee’s anti-inflammatory effects. However, an outside expert warns that this observational study cannot prove a direct link between heavy coffee drinking and better brain aging, particularly in people with A-Fib. “Other studies have shown coffee has cognitive-enhancing functions across the board. This, however, is not specific to the A-Fib population. We cannot conclude that coffee prevents long-term cognitive decline,” said Dr. Jose Joglar , a professor of internal medicine at UT Southwestern Medical Center in Dallas. “Coffee does not seem to worsen A-Fib so there is no need to stop drinking it,” Joglar continued. “However, we cannot say starting to drink coffee would prevent A-Fib or prevent long-term cognitive decline.” Researchers also noted that the study measured brain health and coffee consumption at the same point in time, so it could not track the long-term effect of coffee on brain aging over time. “To detect a relevant cognitive decline, a follow-up of at least 5 to 10 years is required,” Barbagallo said. “However, the nutritive habits including coffee consumption reported by participants reflect exposure over many years and we likely see here the results of this.” Whatever your topic of interest, subscribe to our newsletters to get the best of Drugs.com in your inbox.