运动营养小红书 | 14个问题详解运动减脂宠儿“咖啡因”！
咖啡因，被大众奉为“能量神器”、“精神支柱”。作为新晋时尚运动宠儿，咖啡因被捧为“运动助手”和“减脂神器”。作为广受欢迎的增强体质辅助剂，针对咖啡因及其积极作用的研究非常的广泛。在谷歌学术上，以“咖啡因”和“运动”为关键词进行搜索，可以得到20多万条结果。尽管有大量的可用数据，但学术界对咖啡因的有效性和安全性仍然存在一定的疑问。
近日，发表在国际知名运动医学领域期刊Journal of the International Society of Sports Nutrition的一篇综述文章Common questions and misconceptions about caffeine supplementation: what does the scientific evidence really show？对有关咖啡因补充剂的文献进行了循证科学评估，为大众所关心的14个与咖啡因密切相关问题进行了回答。
咖啡因会使人在休息时脱水吗？
In summary, previous research has suggested that a dose of ≥300 mg of caffeine may induce acute diuresis. However, recent research examining and controlling for multiple factors that may influence the validity of the study design and the responses of the participants has shown that moderate daily doses of caffeine (3 mg/kg or ~ 250–300 mg), which is above the reported average in the United States, in habitual drinkers do not seem to augment urine volume. In contrast, excessive and impractical doses of caffeine (6 mg/kg or ≥500 mg) may facilitate acute diuresis.
总结：适量咖啡因摄入不会增加尿量，但高剂量可能会。以往的研究表明，剂量≥300 毫克的咖啡因可诱发急性利尿。然而，最近的研究对可能影响研究设计有效性和参与者反应的多种因素进行了检查和控制，结果表明，习惯饮酒者每天摄入适量咖啡因（3 毫克/千克或约 250-300 毫克）（高于美国报告的平均水平）似乎不会增加尿量。相反，过量和不切实际的咖啡因剂量（6 毫克/千克或≥500 毫克）可能会促进急性利尿。
运动时，咖啡因是否会使人脱水？
In summary, sweat rate, hydration strategy, and genetics appear more influential on hydration status than reasonable caffeine intake alone. The diuretic effect may be minor or non-existent; however, appropriate fluid intake prevents negative effects on fluid balance. A potential confounder is whether caffeine is consumed as a pill or as part of a multi-ingredient pre-workout supplement with other ingredients and extra fluid.
总结：适量咖啡因摄入不会显著影响运动中的体液平衡。出汗率、补水策略和遗传因素对水合状态的影响似乎比适量咖啡因摄入本身更为重要。咖啡因的利尿效果可能较小或不存在；然而，适当的液体摄入可以防止对液体平衡的负面影响。可能的考虑因素是咖啡因是以药片形式摄入，还是作为含有其他成分和额外液体的多成分锻炼前补充剂的一部分。
咖啡因会促进体内脂肪的流失吗？
In summary, in longer-term caffeine studies examining weight loss, conflicting results may be due to several limiting issues, such as the standardization of dietary intake. Another variable is whether the participants were caffeine naïve prior to the study. If not, perhaps they are habituated to the caffeine dose during the course of the study, thereby minimizing weight loss. The other issue is the dose of caffeine utilized and perhaps whether overweight or non-overweight participants were involved.
总结：目前证据不足以支持咖啡因具有减脂效果。在研究长期咖啡因摄入与体重减轻的实验中，可能由于几个限制性问题导致结果存在冲突，例如饮食摄入的标准化问题。另一个变量是参与者在研究开始前是否对咖啡因不敏感。如果不是，那么在研究过程中他们可能已经对咖啡因剂量产生了耐受性，从而最小化了体重减轻的效果。另一个问题是所使用的咖啡因剂量，以及可能涉及的参与者是否超重或非超重。
咖啡因对上肢和下肢力量表现的影响是否不同？
In summary, caffeine’s ergogenic effects on upper versus lower body strength depend on dose, individual differences, muscle group size, and activity type rather than a clear bias. The advantages are situational and unique rather than inherent in either the upper or lower body.
总结：咖啡因对上肢与下肢力量表现的促进作用取决于剂量、个体差异、肌肉群大小和活动类型，而并非有一个明确的偏向。其优势是情境性和独特性的，而不是固有的存在于上肢或下肢。
咖啡因与抑郁之间有关系吗？
In summary, the relationship between caffeine and depression is highly individualized. While moderate caffeine consumption may provide temporary relief from some depressive symptoms and even have potential mood-enhancing effects for some individuals, excessive or poorly managed caffeine intake can exacerbate anxiety, disrupt sleep, and lead to negative mental health outcomes. It is crucial for individuals with depression to be mindful of their caffeine consumption and its impact on their well-being, as well as to seek professional guidance if necessary, as well as consider any other physical diagnoses present.
总结：咖啡因与抑郁之间的关系存在高度个体化差异。虽然适量摄入咖啡因可以暂时缓解某些抑郁症状，甚至对某些人有潜在的情绪促进作用，但过量或管理不当的咖啡因摄入会加剧焦虑、扰乱睡眠，并导致负面的心理健康结果。对于抑郁症患者来说，关键是要注意咖啡因的摄入量及其对自身健康的影响，必要时寻求专业指导，并考虑其他身体诊断。
摄入过多咖啡因会致命吗？
In summary, caffeine can be lethal when overdosed, but this is not typically possible in healthy persons when consumed in caffeinated beverages like coffee and tea. At a potentially lethal dose of >5000 mg or 5 grams, it is unlikely that an individual would overdose via the consumption of caffeinated beverages.
总结：过量摄入咖啡因可能致命，但健康人在饮用咖啡和茶等含咖啡因的饮料时通常不会出现这种情况。在潜在致死剂量大于5000毫克或5克的情况下，个人不太可能通过饮用含咖啡因的饮料过量摄入咖啡因。
咖啡因的影响存在性别差异吗？
In summary, the literature regarding sex differences in response to caffeine is mixed. Possible contributing factors such as estradiol103 and oral contraceptive use decrease CYP1A2 activity, which is directly involved in caffeine metabolism. Menstruation and subsequent variations in hormones and other physiological differences may account for the reported sex differences. Likewise, caffeine’s effects on sports performance are mixed. Caffeine is an ergogenic aid, and even the placebo effect of caffeine improves sports performance irrespective of sex, with some studies reporting greater performance advantages in males.
总结：有关咖啡因反应的性别差异的文献资料不一。雌二醇103 和口服避孕药等因素可能会降低 CYP1A2 的活性，而 CYP1A2 直接参与咖啡因的代谢。月经和随之而来的荷尔蒙变化以及其他生理差异可能是造成报告中的性别差异的原因。同样，咖啡因对运动表现的影响也不尽相同。咖啡因是一种增强体质的辅助剂，即使是咖啡因的安慰剂效应也能提高运动成绩，而与性别无关，但有些研究报告称男性在运动成绩方面更具优势。
习惯性摄入咖啡因是否会影响对急性咖啡因补充剂的表现反应？
In summary, the preponderance of the evidence suggests that habitual caffeine intake does not negatively impact performance following acute caffeine administration. It may be that a dosage of 6–9 mg/kg of caffeine is necessary to affect performance. However, with the majority of studies not reporting habitual caffeine intake, more research is needed.
总结：大量证据表明，习惯性摄入咖啡因不会对急性摄入咖啡因后的表现产生负面影响。影响成绩可能需要6-9毫克/千克咖啡因的剂量。不过，由于大多数研究没有报告习惯性咖啡因摄入量，因此还需要进行更多的研究。
咖啡因对每个人都有效吗？
In summary, there is clear evidence that a large inter-individual variability exists with regard to the ergogenic response to caffeine ingestion. Furthermore, the performance-enhancing effects of caffeine are not always repeatable. Presently, if non-responders to caffeine do exist, it is likely rare. Future research using repeated tests with multiple tasks and dosing strategies is required to confirm the responsiveness of an individual.
总结：有明确的证据表明，摄入咖啡因后的运动能力反应存在很大的个体差异。咖啡的增强效果并非总是可重复的。目前，如果确实存在对咖啡因无反应的人，那也很可能是极少数。未来的研究需要使用多种任务和剂量策略进行重复测试，以确认个体的反应性。
咖啡因会导致心脏问题吗？
In summary, the overall impact of caffeine on an individual’s cardiovascular risk profile is likely to be influenced by a myriad of factors, including dosage, duration of consumption, mode of consumption (e.g., coffee, tea, etc.), and individual metabolic and genetic differences. In addition, much of one’s caffeine consumption is via coffee. It is known that regular coffee consumption confers a myriad of benefits. The current FDA guidelines suggest consuming no more than 400 mg daily. Clearly, the effects of 400 mg will differ if one’s body mass is 60 kg vs. 100 kg. Moreover, this must be tempered with the fact that many exercising individuals may exceed that dose when caffeine is used as an ergogenic aid.
总结：咖啡因对个人心血管风险状况的总体影响可能受到多种因素的影响，包括剂量、饮用时间、饮用方式（如咖啡、茶等）以及个人代谢和遗传差异。此外，一个人摄入的大部分咖啡因都是通过咖啡摄入的。众所周知，经常饮用咖啡有很多好处。美国食品和药物管理局（FDA）的现行指南建议每天饮用不超过400毫克。显然，如果一个人的体重是60千克与100千克，400 毫克的效果就会不同。此外，还必须考虑到这样一个事实，即许多运动者在使用咖啡因作为运动辅助剂时，可能会超过这个剂量。
咖啡因会促进骨矿物质流失吗？
In summary, there is evidence to suggest that ≤ 4 cups of coffee (≤400 mg of caffeine) is the threshold for concern regarding BMD and/or fracture risk, primarily in females. It is unclear whether any presumed effect is from beverages such as tea, coffee, or energy drinks compared to caffeine alone. Moreover, the lack of RCTs on this issue makes it difficult to arrive at a definitive conclusion. Additional clinical research, specifically RCTs, is needed to explore the potential dose-response relationship between caffeine consumption and bone health and investigate relevant confounding variables (i.e. diet, population, and mode of caffeine delivery [e.g. coffee, energy drinks, tea, soft drinks, etc.) before drawing any firm conclusions.
总结：有证据表明，≤ 4 杯咖啡（≤ 400 毫克咖啡因）是关注 BMD 和/或骨折风险的临界值，主要针对女性。目前尚不清楚与单纯咖啡因相比，茶、咖啡或能量饮料等饮料是否会产生任何假定的影响。此外，由于缺乏有关这一问题的研究性试验，因此很难得出明确的结论。在得出确切结论之前，还需要进行更多的临床研究，特别是研究性临床试验，以探讨咖啡因摄入量与骨骼健康之间的潜在剂量反应关系，并调查相关的混杂变量（即饮食、人群和咖啡因的摄入方式[如咖啡、能量饮料、茶、软饮料等]）。
孕妇应避免摄入咖啡因吗？
In summary, the consensus derived from observational studies and meta-analyses is that maternal caffeine intake consistently links to adverse pregnancy outcomes. The cumulative scientific evidence suggests that pregnant women and those considering pregnancy should be advised to abstain from caffeine.
总结：观察性研究和Meta分析得出的共识是，孕产妇咖啡因摄入量一直与不良妊娠结局有关。累积的科学证据表明，应建议孕妇和考虑怀孕的妇女禁用咖啡因。
咖啡因会上瘾吗？
In summary, though it appears that caffeine has the potential to be abused by some and has established withdrawal symptoms, current mechanistic evidence and SUD criteria do not fully support the classification of caffeine as addictive. The potential for caffeine dependency or CUD may be revisited in future DSM and ICD guidelines as additional research evidence becomes available.
总结：尽管咖啡因似乎有可能被某些人滥用，并且已经出现了戒断症状，但目前的机理证据和SUD标准并不完全支持将咖啡因归类为成瘾。随着更多研究证据的出现，咖啡因依赖或CUD的可能性可能会在未来的DSM和ICD指南中重新讨论。
起床后等待1.5-2.0小时再摄入咖啡因是否有助于避免午后“崩溃”？
In summary, though there may be an upside to delaying morning caffeine intake under conditions of sufficient sleep, this has to do with the magnitude of effect rather than proposed mechanisms related to prolonging the cortisol peak, continued declines in adenosine, or avoiding an afternoon “crash.” A significant drawback in the argument related to cortisol is that a similar effect occurs with intense resistance exercise performed soon after waking. Following this line of reasoning would imply that this type of early morning exercise should be avoided; however, this notion makes no scientific or pragmatic sense. The suggestion that adenosine continues to decline upon waking is also scientifically inaccurate and not supported by research. There is also no evidence that caffeine ingestion upon waking is somehow responsible for an afternoon “crash” or that delaying consumption would somehow prevent this if it did occur.
总结：虽然在睡眠充足的条件下推迟早晨摄入咖啡因可能有好处，但这与效果的大小有关，而不是与延长皮质醇峰值、腺苷持续下降或避免下午 "崩溃 "有关的机制。与皮质醇有关的论点的一个重大缺陷是，在睡醒后不久进行的高强度阻力运动也会产生类似的效果。按照这种思路推理，就意味着应该避免清晨进行这种类型的运动；然而，这种观点既没有科学道理，也没有实际意义。关于腺苷在醒来后会继续下降的说法在科学上也是不准确的，没有得到研究的支持。此外，也没有证据表明起床后即刻摄入咖啡因会导致下午的“崩溃”，或者推迟摄入咖啡因会在某种程度上防止这种情况的发生。
*中文翻译仅供参考，请以英文原文为准
关于期刊
Journal of the International Society of Sports Nutrition
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