Caffeine is a substance that many start the day with tofeel awake and focused。其他人则在特殊场合使用它，例如长期驱动器或深夜活动来保持警惕。Athletes use it to boost performance。It is the most well-studied, legal performance aid.
Since caffeine was removed from the World Anti-Doping Agency’s list of banned substances, roughly75%of athletes use caffeine strategically for performance. While it is popular and known to提升结果，补充剂的缺点可能并不适合所有人。
REQUIRES MORE FOR THE SAME RESULT
The brain can increase receptors for caffeine with long term, high intake which means you need more to feel the same effects. Consuming a little bit each day can easily lead to consuming a moderate and then a large amount because you build a tolerance to it. This could happen without you even being aware, due to the prevalence of caffeine in food, drinks and supplements — caffeine is in waters, gums, sport gels; even a standard cup of coffee or tea can vary greatly in caffeine content.
The fix:Tracking your eating and drinking habits can be a great tool to figure out how much you are taking in each day.
INTERFERES WITH SLEEP
Caffeine’s main job is to keep you alert, which is great — unless you need to get some shut-eye. How quickly or slowly you process caffeine varies from person to person based on factors such as age, gender, diet, disease and genetics. The stimulant typically stays in the body for 4–6 hours. Athletes who consume high amounts of caffeine for late-day training or to combat feeling exhausted after early morning training, might be hindering their sleep and ultimately their performances.
The fix:尝试在中午之前食用咖啡因，以增加您获得足够休息的几率。
阻碍营养的吸收
那些关心健康习惯的人通常也投资于健康的饮食习惯。不幸的是，食用咖啡因会干扰保持活跃身体健康所需的关键营养素，例如B族维生素，铁，钙和镁。在fact, consuming caffeine with a meal can reduce the absorption of heme iron by 50% and non-heme iron by more than 60%.
The fix:To ensure you’re still getting enough nutrients everyday, consume caffeine away from meals, eat nutrient-rich foods and take a daily vitamin to cover your bases.
影响心脏健康
关于咖啡因是对您的心脏是好还是坏的，可用的科学文献并不能明确结论。通常，每天使用多达600毫克（大约6杯咖啡）被认为是安全的，但是对于那些耗费该数量的人来说，研究有限。大约25％的成年人消耗超过600毫克，这使其成为合理的关注点。尽管参与持续的身体健康的人通常比久坐的人具有更好的心脏健康，但在严重的表演中（例如马拉松比赛）经历心脏事件的风险有所增加。食用过多的赛前咖啡因可能会增加这种风险。
The fix:Wear a heart rate monitor during workouts to get a better idea of your caffeine response — tracking if and how much caffeine was consumed. Reducing caffeine content before/ during workouts might be key if you are a high consumer.
INTERFERES WITH MEDICATION
咖啡因可以通过阻止或加剧吸收来与许多药物进行负相互作用。一studyfound taking thyroid medication with coffee reduced absorption of the medication by roughly 50%. Some antibiotics, osteoporosis drugs and antidepressants can also be affected by caffeine consumption.
The fix:If you take medication, speak to your doctor or pharmacist and act accordingly.
THE BOTTOM LINE
这些问题中的许多是个人的，并且从个人到个人都有很大不同，这使得难以建议的具体准则。如果您怀疑咖啡因会导致您的身体或心灵压力，请开始reducing the amount you consume each day。Once the substance is eliminated, you can evaluate how you feel and whether or not you wish to return to using caffeine daily, for performances only or not at all.
