Coffee和茶非常健康的饮料。
Most types contain咖啡因, a substance that may boost your mood, metabolism and mental and physical performance (
研究还表明，当大多数人以低至中等数量消费时，这对大多数人都是安全的（
但是，高剂量的咖啡因可能具有不愉快甚至危险的副作用。
研究表明，您的基因对您对其的耐受性有重大影响。有些人比其他人在没有负面影响的情况下可以食用咖啡因多得多（
What’s more, individuals who aren’t used to caffeine may experience symptoms after consuming what is typically considered a moderate dose (
这是咖啡因过多的9个副作用。
Caffeine is known to increase alertness.
It works by blocking the effects of adenosine, a brain chemical that makes you feel tired. At the same time, it triggers the release of adrenaline, the “fight-or-flight” hormone associated with increased energy (
However, at higher doses, these effects may become more pronounced, leading to anxiety and nervousness.
实际上，咖啡因诱导的焦虑症是由美国精神病学协会发布的诊断和统计手册（DSM）中列出的四种与咖啡因相关的综合症之一。
Extremely high daily intakes of 1,000 mg or more per day have been reported to cause nervousness, jitteriness and similar symptoms in most people, whereas even a moderate intake may lead to similar effects in caffeine-sensitive individuals (9,
此外，已经证明适度剂量会导致呼吸迅速，并在一次坐着消耗时增加压力水平（
One study in 25 healthy men found that those who ingested approximately 300 mg of caffeine experienced more than double the stress of those who took a placebo.
Interestingly, stress levels were similar between regular and less frequent caffeine consumers, suggesting the compound may have the same effect on stress levels regardless of whether you drink it habitually (
Nevertheless, these results are preliminary.
Coffee’s咖啡因contentis highly variable. For reference, a large (“grande”) coffee at Starbucks contains about 330 mg of caffeine.
If you notice that you often feel nervous or jittery, it might be a good idea to look at your caffeine intake and cut it back.
Summary:虽然
低到中度剂量的咖啡因会增加机敏性，较大的含量可能
lead to anxiety or edginess. Monitor your own response in order to determine
有多少you can tolerate.
Caffeine’s ability to help people stay awake is one of its most prized qualities.
On the other hand, too much caffeine can make it difficult to get enough restorative sleep.
Studies have found that higher caffeine intake appears to increase the amount of time it takes to fall asleep. It may also decrease total sleeping time, especially in the elderly (
By contrast, low or moderate amounts of caffeine don’t seem to affect sleep very much in people considered “good sleepers,” or even those with self-reported insomnia (
You may not realize that too much caffeine is interfering with your sleep if you underestimate the amount of caffeine you’re taking in.
虽然coffee and tea are the most concentrated sources of caffeine, it is also found in soda, cocoa, energy drinks and several types of medication.
For example, an energy shot may contain up to 350 mg of caffeine, while some energy drinks provide as much as a whopping 500 mg per can (
Importantly, the amount of caffeine you can consume without affecting your sleep will depend on your genetics and other factors.
In addition, caffeine consumed later in the day may interfere with sleep because its effects can take several hours to wear off.
研究表明，虽然咖啡因平均在您的系统中持续五个小时，但该时间段可能从一个半小时到九个小时不等（取决于个人（
一项研究调查了摄入咖啡因的时间如何影响睡眠。研究人员在睡前六个小时，就寝前三个小时或就在睡前六个小时，就给了12名健康的成年人400毫克咖啡因。
Both the time it took all three groups to fall asleep and the time they spent awake at night increased significantly (
这些结果表明，重要的是要注意咖啡因的数量和时机以优化您的睡眠。
Summary:咖啡因可以
帮助您白天保持清醒，但可能会对您的睡眠产生负面影响
质量和数量。下午早上切断咖啡因的消费
避免睡眠问题。
Many people find that a morning cup of coffee helps get their bowels moving.
Coffee’s laxative effect has been attributed to the release of gastrin, a hormone the stomach produces that speeds up activity in the colon. What’s more, decaffeinated coffee has been shown to produce a similar response (
However, caffeine itself also seems to stimulate bowel movements by increasing peristalsis, the contractions that move food through your digestive tract (
Given this effect, it’s not surprising that large doses of caffeine may lead to loose stools or even diarrhea in some people.
虽然for many years coffee was believed to cause stomach ulcers, a large study of more than 8,000 people didn’t find any link between the two (
On the other hand, some studies suggest that caffeinated beverages may worsen gastroesophageal reflux disease (GERD) in some people. This seems to be especially true of coffee (
In a small study, when five healthy adults drank caffeinated water, they experienced a relaxation of the muscle that keeps stomach contents from moving up into the throat — the hallmark of GERD (
Since coffee can have major effects on digestive function, you may want to cut back on the amount you drink or switch to tea if you experience any issues.
Summary:虽然small
适度的咖啡可以改善肠道运动，较大的剂量可能会导致
to loose stools or GERD. Reducing your coffee intake or switching to tea may be
beneficial.
Rhabdomyolysis is a very serious condition in which damaged muscle fibers enter the bloodstream, leading to kidney failure and other problems.
Common causes of rhabdomyolysis include trauma, infection, drug abuse, muscle strain and bites from poisonous snakes or insects.
In addition, there have been several reports of rhabdomyolysis related to excessive caffeine intake, although this is relatively rare (
在一种情况下，一名妇女在喝了32盎司（1升）含有大约565毫克咖啡因的咖啡后出现恶心，呕吐和黑尿。幸运的是，她在接受药物治疗和液体治疗后康复（
Importantly, this is a large dosage of caffeine to consume within a short period of time, especially for someone who isn’t used to it or is highly sensitive to its effects.
In order to reduce the risk of rhabdomyolysis, it’s best to limit your intake to about 250 mg of caffeine per day, unless you’re used to consuming more.
Summary:People may
摄取后，出现横纹肌溶解或受损肌肉的崩溃
大量咖啡因。如果您是每天将摄入量限制为250毫克
uncertain of your tolerance.
Despite all of caffeine’s health benefits, there’s no denying that it may become habit-forming.
一项详细的评论表明，尽管咖啡因触发了某些与可卡因和苯丙胺类似的脑化学物质，但它不会像这些药物那样引起经典成瘾（这些药物的方式（
However, it may lead to psychological or physical dependency, especially at high dosages.
在一项研究中，通常有16人在没有咖啡因过夜后，通常会消耗高，中度或没有咖啡因的咖啡因。只有高咖啡因使用者对咖啡因相关单词有偏见，并且咖啡因渴望很强（
此外，咖啡因摄入量的频率似乎在依赖性中起作用。
在另一项研究中，有213位咖啡因用户在不消耗16个小时后完成问卷。每天用户的头痛，疲劳和其他戒断症状的增加比非每日用户（
即使该化合物似乎并没有引起真正的成瘾，但如果您定期喝很多咖啡或其他含咖啡因的饮料，则很有可能会依赖它的效果。
Summary:没有
咖啡因for several hours may lead to psychological or physical withdrawal
symptoms in those who consume large amounts on a daily basis.
Overall, caffeine doesn’t seem to increase the risk of heart disease or stroke in most people.
However, it has been shown to raise blood pressure in several studies due to its stimulatory effect on the nervous system (
Elevated blood pressure is a risk factor for heart attack and stroke because it may damage arteries over time, restricting the flow of blood to your heart and brain.
Fortunately, caffeine’s effect on blood pressure seems to be temporary. Also, it seems to have the strongest impact on people who aren’t used to consuming it.
高咖啡因intake has also been shown to raise blood pressure during exercise in healthy people, as well as in those with mildly elevated blood pressure (
因此，注意咖啡因的剂量和时机很重要，尤其是如果您已经患有高血压。
Summary:Caffeine seems
to raise blood pressure when consumed at high doses or prior to exercise, as
well as in people who rarely consume it. But this effect may only be temporary,
因此，最好监视您的响应。
The stimulatory effects of high caffeine intake may cause your heart to beat faster.
这也可能导致心跳节奏改变，称为心房颤动，这是在食用含有极高剂量咖啡因的能量饮料的年轻人中报道的（
In one case study, a woman who took a massive dose of caffeine powder and tablets in an attempted suicide developed a very rapid heart rate, kidney failure and other serious health issues (
However, this effect doesn’t seem to occur in everyone. Indeed, even some people with heart problems may be able to tolerate large amounts of caffeine without any adverse effects.
In one controlled study, when 51 heart failure patients consumed 100 mg of caffeine per hour for five hours, their heart rates and rhythms remained normal (
Regardless of the mixed study results, if you notice any changes in your heart rate or rhythm after drinking caffeinated beverages, consider decreasing your intake.
Summary:Large doses of
咖啡因可能会增加某些人的心率或节奏。这些效果出现
因人而异。如果您感觉到它们，请考虑减少您的
intake.
Coffee, tea and other caffeinated beverages are known to boost energy levels.
However, they can also have the opposite effect by leading to rebound fatigue after the caffeine leaves your system.
One review of 41 studies found that although caffeinated energy drinks increased alertness and improved mood for several hours, participants were often more tired than usual the following day (
Of course, if you continue to drink lots of caffeine throughout the day, you can avoid the rebound effect. On the other hand, this may affect your ability to sleep.
To maximize caffeine’s benefits on energy and avoid rebound fatigue, consume it in moderate rather than high doses.
Summary:虽然
咖啡因provides energy, it can indirectly lead to fatigue when its effects
wear off. Aim for moderate caffeine intake to help minimize rebound fatigue.
Increased urination is a common side effect of high caffeine intake due to the compound’s stimulatory effects on the bladder.
You may have noticed that you need to urinate frequently when you drink more coffee or tea than usual.
Most research looking at the compound’s effects on urinary frequency has focused on older people and those with overactive bladders or incontinence (
In one study, 12 young to middle-aged people with overactive bladders who consumed 2 mg of caffeine per pound (4.5 mg per kilogram) of body weight daily experienced significant increases in urinary frequency and urgency (
For someone weighing 150 pounds (68 kg), this would equate to about 300 mg of caffeine per day.
In addition, high intake may increase the likelihood of developing incontinence in people with healthy bladders.
一项大型研究研究了高咖啡因摄入量对超过65,000名没有尿失禁的女性尿失禁的影响。
那些每天摄入超过450毫克significantly increased risk of incontinence, compared to those who consumed less than 150 mg per day (
如果您喝了很多含咖啡因的饮料，并且觉得您的排尿比应有的频繁或紧急，那么减少摄入量可能是个好主意，看看您的症状是否有所改善。
Summary:高咖啡因
intake has been linked to increased urinary frequency and urgency in several
studies. Reducing your intake may improve these symptoms.
Light-to-moderate caffeine intake seems to provide impressive health benefits in many people.
另一方面，很高的剂量可能会导致副作用，从而干扰日常生活，甚至可能引起严重的健康问题。
虽然responses vary from person to person, the effects of high intake demonstrate that more isn’t necessarily better.
To get the benefits of caffeine without undesirable effects, conduct an honest assessment of your sleep, energy levels and other factors that might be affected, and reduce your intake if needed.
