What does caffeine do to your body?<\/h2>\n\n
Caffeine is chemically closely related to adenosine. Adenosine builds up in the brain throughout the day and makes you feel tired; it\u2019s essentially the body\u2019s built-in fatigue meter. The higher your adenosine levels, the more tired you feel. Caffeine blocks the adenosine receptors and essentially takes their place. The result: lower adenosine levels, and you feel more alert, even though your actual need for sleep hasn\u2019t changed (1<\/strong><\/a>). <\/p>\n\n More than 95% of caffeine is metabolized by the liver, specifically by the enzyme CYP1A2. This enzyme primarily converts caffeine into the metabolite paraxanthine. The rate at which this occurs varies greatly from person to person, sometimes by a factor of 5 to 6. More on this below in the section on genetics (2<\/strong><\/a>). <\/p>\n\n Your brain constantly produces adenosine\u2014the substance that tells you, \u201cSlow down, you\u2019re tired.\u201d Caffeine blocks this very mechanism. It binds to the adenosine receptors (A1\/A2A) in the brain and hijacks them before adenosine can even dock. The result: a lower perceived exertion (RPE), greater alertness, and higher levels of dopamine and norepinephrine in your system\u2014your body feels more refreshed than it actually is.<\/p>\n\n For a long time, the rule of thumb was: Coffee causes heart palpitations, so it\u2019s bad for the heart. That\u2019s exactly what the CRAVE study set out to investigate. For two weeks, 100 healthy adults had their heart rates monitored around the clock, alternating daily between drinking coffee and abstaining from it\u2014in a fair comparison, so everyone had one \u201ccoffee day\u201d and one \u201cno-coffee day.\u201d The result: Coffee did not increase the risk of dangerous heart rhythm irregularities. (8<\/strong><\/a>).<\/p>\n\n There is also no increased risk associated with atrial fibrillation. In a large analysis of the UK Biobank involving over 449,000 participants, coffee consumption was even associated with a slightly reduced rate (9<\/strong><\/a>). <\/p>\n\n And what about the arteries themselves? This is where it gets really interesting. Chlorogenic acid, an antioxidant found in coffee, has been shown in controlled studies to improve endothelium-dependent vasodilation (FMD), an important marker of healthy, elastic blood vessels (10<\/strong><\/a>). <\/p>\n\n It’s worth taking a closer look here, because the preparation method makes all the difference (11<\/strong><\/a>):<\/p>\n\n In the short term, caffeine can slightly raise blood pressure, especially if your body isn\u2019t used to it. The effect begins after about 30 minutes and peaks after 1 to 2 hours. With regular consumption, however, a significant tolerance develops. Daily intakes of up to 400 mg do not significantly increase resting blood pressure in the long term, and coffee is not associated with an increased risk of hypertension (12<\/strong><\/a>). <\/p>\n\n The topic that catches most people’s attention. Let’s take a look at the four relevant categories. <\/p>\n\n During roasting, compounds such as acrylamide and furan are automatically formed as a result of the heat. Acrylamide levels are particularly high in light roasts, while furan levels tend to be higher in dark roasts. There is no roasting method that minimizes both at the same time. However, the measured levels are below the relevant risk thresholds (13<\/strong><\/a>). <\/p>\n\n Yes, mold on green coffee beans can produce the mycotoxin OTA. However, espresso reduces the OTA content by nearly 50%, while filter coffee reduces it to a much lesser extent. A global analysis of 3,256 coffee samples shows that even four cups a day provide only about 2% of the daily intake considered safe (14<\/strong><\/a>). <\/p>\n\n Cadmium, lead, and other elements enter plants through the soil and fertilizers. However, the relevant risk measure (Total Target Hazard Quotient) is below the critical value of 1 in all countries studied worldwide (15<\/strong><\/a>). <\/p>\n\n Washing, roasting, and brewing eliminate pesticide residues almost completely\u2014in some cases up to 100%. Virtually nothing remains in the finished cup (16<\/strong><\/a>). <\/p>\n\n The story of contaminants is actually a success story for processing. Roasting, washing, and steeping do most of the work for you. <\/p>\n\n A classic among exercise myths: Coffee dehydrates the body, so you have to drink extra water to compensate. A study lasting several days involving 50 regular coffee drinkers shows: Four cups of coffee a day for three days versus the same amount of water for three days\u2014no difference in fluid balance, urine, or blood values (17<\/strong><\/a>). Another 11-day study involving varying amounts of caffeine reached the same conclusion: no signs of a diuretic effect (18<\/strong><\/a>). <\/p>\n\n Relevant for athletes: According to an analysis of 16 studies, even the mild diuretic effect that caffeine can have at rest disappears almost completely as soon as exercise is added (19<\/strong><\/a>).<\/p>\n\n In other words: The coffee you drink before your workout counts toward your fluid intake as usual\u2014no extra water is needed. This applies to moderate, normal consumption. On hot days and during long workouts, be sure to drink enough anyway. <\/p>\n\n This is where things get serious, because this is the area where the evidence is truly unequivocally negative. A large meta-analysis of 24 studies shows (20<\/strong><\/a>): <\/p>\n\n The tricky part is this:<\/strong> Even if taken six hours before bedtime, a 400-mg dose of caffeine will still cost you over an hour of sleep, according to a controlled study (21<\/strong><\/a>). So, depending on how much caffeine you consume, you should allow plenty of time before bedtime if your sleep and recovery are important to you. <\/p>\n\n Not everyone metabolizes caffeine the same way, and that\u2019s not just a figment of your imagination. The key difference lies in the CYP1A2 gene. People with the AA genotype are considered fast metabolizers, while those with the C allele (AC\/CC) break down caffeine significantly more slowly. CYP1A2 activity can vary by a factor of 5 to 6 between individuals. <\/p>\n\n This has real-world implications for performance: At 4 mg\/kg of caffeine, fast metabolizers improved their 10-km time trial performance by 6.8%. Slow metabolizers, on the other hand, were 13.7% slower (22<\/strong><\/a>). <\/p>\n\n Genetics also play a role in sleep patterns, specifically through the ADORA2A gene, which regulates the sensitivity of adenosine receptors. If coffee makes you jittery in the afternoon or keeps you awake at night, you\u2019re probably a slow metabolizer or particularly sensitive to ADORA2A. In that case, stick to lower doses and cut back earlier. <\/p>\n\n The EFSA (European Food Safety Authority) has defined the limit as follows (23<\/strong><\/a>):<\/p>\n\n![\"\"](\"https:\/\/athleatcoach.com\/wp-content\/uploads\/Caffeine-mechanisms-English.jpg\")
<\/figure>\n\nEinfluss auf die sportliche Leistung<\/h2>\n\n
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Caffeine is one of the most effective supplements for boosting performance, but does it have negative effects on health?<\/mark><\/h3>\n<\/blockquote>\n\n
![\"\"](\"https:\/\/athleatcoach.com\/wp-content\/uploads\/heart.jpg\")
<\/figure>\n\nIs coffee bad for the heart?<\/h2>\n\n
Cholesterol: It Depends on How It’s Prepared<\/h3>\n\n
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Der Grund sind die Diterpene Cafestol und Kahweol. Die bleiben im Papierfilter gr\u00f6\u00dftenteils h\u00e4ngen. Trinkst du also viel French Press oder Espresso und hast erh\u00f6hte Cholesterinwerte, ist ein Wechsel zu Filterkaffee eine einfache und sinnvolle Ver\u00e4nderung.<\/mark><\/h3>\n<\/blockquote>\n\n
High Blood Pressure: Acute, Yes; Long-Term, No<\/h3>\n\n
![\"\"](\"https:\/\/athleatcoach.com\/wp-content\/uploads\/kaffee-cover-bild-chatGPT-1024x1024.png\")
<\/figure>\n\nSchadstoffe: Mythos oder wirkliches Risiko?<\/h2>\n\n
Roasting by-products (acrylamide, furan, 5-HMF):<\/h3>\n\n
Mold (Ochratoxin A):<\/h3>\n\n
Heavy metals:<\/h3>\n\n
Pesticides:<\/h3>\n\n
![\"\"](\"https:\/\/athleatcoach.com\/wp-content\/uploads\/Koffein-dehydrierung-1024x1024.png\")
<\/figure>\n\nDehydriert Kaffee?<\/h2>\n\n
Muss man mehr Wasser trinken?<\/h4>\n\n
Einfluss auf den Schlaf<\/h2>\n\n
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![\"\"](\"https:\/\/athleatcoach.com\/wp-content\/uploads\/caffeine-cut-off-sleep-English-1024x683.png\")
<\/figure>\n\nEinfluss der Genetik<\/h2>\n\n
Schnelle und langsame Abbaurate<\/h4>\n\n
Safety: What are the current limits?<\/h2>\n\n