Coffee & Caffeine - Good or Bad?

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Richard Staudner

The Optimizer

Coffee means many things to us: culture, ritual, social gathering and, of course, taste. Perhaps it's also the only reason to get out of bed before 10 in the morning. As often and regularly as we drink coffee, it definitely doesn't hurt to take a critical look at it.

What is coffee or caffeine actually? And what does it do to my body? Is coffee good or bad for us? In any case, there are enough myths around this topic. There definitely needs to be a little clarity!

The beloved coffee kick  

Coffee, or its main active ingredient caffeine, can be found in a huge range of retail and food service products. From simple espresso, to pumpkin spice latte, to caffeine tablets, we can enjoy it in many colors and forms. In addition to the aroma and ritual with which we associate coffee drinking, we naturally appreciate the stimulating effect that coffee has. For many of us, everyday life without coffee is still hard to imagine. One in the morning, one after lunch and a few in between. Coffee is an integral part of our society. Abstinence from coffee would be a hard blow for many of us and could even affect performance. 

But how does coffee actually work? 

In short, the caffeine in coffee does not increase wakefulness, but prevents fatigue. In fact, it cannot make us "more awake than awake", i.e. increase our performance above our normal level. 

It prevents the fatigue signals from being perceived by our body. This then shows up in both cognitive and physical performance. But let's just look at this a little closer. 

The biochemistry of caffeine

Caffeine belongs to a chemical group of so-called purine alkaloids, which incidentally also includes theobromine, a substance we know from cocoa. 

Caffeine looks similar to the body's own adenosine and can therefore dock onto its receptors. Unlike adenosine, caffeine does not activate the receptors, but simply blocks them. If I now tell you that adenosine is our body's energy brake, so to speak, then you can probably already imagine how the mechanism works. In the morning after waking up and the first light contact, the adenosine level starts to rise slowly to make you really tired towards evening (about 15 hours later). Adenosine thus provides the natural sleep pressure. 

Via the adenosine receptors, fatigue is signaled to us so that we exert ourselves less and come to rest. We can say that biologically our body cells are exhausted and need a break. 

But if the receptors are blocked by caffeine, then we simply don't feel the effect of all the adenosine particles. So coffee is actually fooling us. 

Last but not least, the biphasic effect of coffee and caffeine is interesting: small doses often have the opposite effect than large amounts. One often hears about the phenomenon "I don't react to coffee and can drink an espresso in the evening! (1) 

Interestingly, many primitive peoples independently discovered the effects of coffee, cocoa, guarana and cola early on and used the plants as stimulants or to enhance performance, for example during long hikes or in battle. Thanks to this long history, research became interested in coffee and its ingredients early on, so that today we can draw from a large amount of high-quality literature!

Besides caffeine, coffee also contains several other substances that act on our body! Of these, chlorogenic acid should definitely remain in our minds. It not only has a significant impact on coffee quality and aroma, but is also relevant for many effects. (2) 

Let's take a closer look at how chlorogenic acid and the other ingredients affect our bodies. For the research of this article, I have mainly oriented myself to meta-analyses, which are high-quality overviews that summarize several study results. The data situation on this topic, I can say in advance, is very satisfactory. 

Health effects of coffee and caffeine

Very briefly, in general, coffee seems to have largely positive effects on the body, e.g. in the development of many types of cancer, diabetes, on liver health and cognitive performance. There are clear negative effects during pregnancy and on blood lipid levels. There is also still disagreement about the effect on blood pressure.

The critical issue of blood pressure

Various research results speak of a positive, blood pressure-lowering effect from 2 cups daily (3,4). Some studies make this statement but only about decaffeinated coffee (5)

As always, there are studies that come to completely different conclusions and find, for example, no effect (2). Studies on the function of blood vessels show no clear positive effect (6)

Poor blood lipid levels due to coffee consumption?

According to various studies, coffee consumption has a bad influence on our blood lipid levels. Total cholesterol (TC) as well as LDL cholesterol and triglycerides (TG) are increased. (2,7,8) Additional smoking actually worsens the effect. If you drink less than 3 cups of coffee a day and do not smoke, then the negative effect is reduced. (7)

We must always take into account that our entire lifestyle has an impact and there are many factors that can distort the final result. 

In general, despite all this, cardiovascular diseases occur less frequently in coffee-drinking people than in abstinent ones. Whether the cause lies in the coffee or in other common circumstances is not clear. (8).

Perhaps the reason for this connection lies in the effect of coffee on the body's hormonal balance, because coffee consumption seems to increase adiponectin in women. This is a hormone that acts against high blood pressure, against diabetes and against the clogging of blood vessels (arteriosclerosis). As you can see, the issue of blood pressure is somewhat controversial regarding coffee consumption. 

Coffee against diabetes? 

Chlorogenic acid, mentioned at the beginning, seems to lower sugar in the blood and increase sensitivity to insulin. (2,10) More sensitive in insulin production? That sounds good. 

In general, this appears to mean a lower risk of type 2 diabetes. (8) By the way, this effect is also similar with decaffeinated coffee. Another analysis even claims that only decaffeinated coffee has a positive effect, but normal coffee does not. (5)

Coffee in the fight against cancer

Coffee appears to have a protective effect on the development of cancer. Coffee consumption can provide at least some protection against a variety of cancers. These include cancer of the endometrium, liver, prostate, pancreas, skin and mouth. (2,8). There is uncertainty about rectal and esophageal cancer. (11,12). On stomach cancer coffee seems to have a bad influence (2). This may also have to do with the method of preparation. 

An increased risk of lung cancer is also controversially discussed. This may be increased at first glance, but if you consider that many coffee drinkers also smoke and take this into account statistically, you can no longer see a significant connection. (2,8)

Pleasurably protect the liver & kidneys 

The liver shows the clearest protective effect. A lower risk of non-alcoholic fatty liver, liver fibrosis and cirrhosis. (2,8,13)

It is now thought to reduce the risk of chronic kidney disease (14), although a few years ago this was still considered uncertain (15).

What does our brain say about coffee?

Coffee consumption also seems to have an impact on our cognitive performance and mental health, namely reducing the risk of developing or progressing Parkinson's disease and depression (2,8,16,17). Dementia (Alzheimer's disease), and cognitive performance is assessed differently in the analyses, partly positive (2,8,18) or one came to the conclusion that there were no effects (19,20) gives.

So overall a positive effect on our brain and cognitive performance. 

Caution during pregnancy

Caffeine is broken down much more slowly during pregnancy and therefore has a longer effect, and can also cross the placental barrier and pass to the fetus. It increases the risk of low birth weight, premature birth, miscarriage in the 1st and 2nd trimesters, and has been linked to early childhood leukemia. (2,8)

Our bones also want to be healthy

Women are said to have an increased risk of bone fractures (8)but perhaps this is only relevant for women with calcium deficiency. Calcium is enormously important for bone function and women are anyway, hormone-dependent, more at risk for bone fractures in old age. Among other things, substances in coffee bind calcium and thus reduce the amount available to the body. Thus, the consumption of coffee directly after a meal is somewhat more questionable, because coffee can influence the calcium absorption from the food. 

Living longer through coffee?

Last but not least, we can see from huge population studies that coffee consumption significantly reduces mortality. We're talking about all-cause, cardiovascular and cancer mortality. These are incredible results! 

The effect has a U-shaped curve and the mortality is lower with low consumption, i.e. between 2 and 3.5 cups, than with no or more coffee. By the way, the whole thing looks similar with decaffeinated coffee. Women need slightly less coffee than men for the positive effect. Despite all this: These are only observational studies over many years and the influence of other external factors can never be excluded. (8,21,22)

Is decaffeinated coffee also useful?

There are, of course, many different types of coffee and preparation methods and from the studies it has been shown that in many cases decaffeinated coffee works at least as well, sometimes even better, compared to caffeinated.

There is also a method of coffee treatment, removing the outer wax layer of the beans, which in animal studies protects the gastric mucosa. 

Robusta varieties have a higher content of chlorogenic acid, more caffeine and a more bitter aroma than other varieties. Whether this has health benefits is still pure speculation and has not been studied in detail. Unfortunately, the stronger the coffee is roasted and the milder it tastes, the lower the chlorogenic acid content. (1)

Addicted to coffee? At what point is it too much?

With high amounts of coffee, the positive effect decreases again in many cases. We remember the U-shaped curves. More is not more, or more is definitely not better!

Moreover, from 5-10 cups a day (i.e. around 1g of caffeine), negative effects can actually occur, especially related to the excitation of the nervous system and muscles. 

Coffee addiction is a different matter: there are biological withdrawal symptoms, but they are not accompanied by incapacity to work, psychological disorders and an uncontrollable craving, as is the case with other addictive disorders. Experiments have also shown that for regular coffee drinkers, a caffeine tablet taken with water does not quench the craving, which underscores the strong social, gustatory, and ritualistic components of coffee consumption. 

Despite everything, we should not forget what caffeine actually does: caffeine prevents us from feeling our own tiredness. This can be practical, but also dangerous and questionable. If you can't function without coffee, you might consider reducing some stress for the sake of your health and giving yourself some rest. Are you getting enough quality sleep? Are you constantly consumed by mental health issues, or do you have to do more than you're capable of? Take care of your body, because as stupid as it may sound: You only have one and eventually it will tell you if you exploit it permanently. 

In any case, the two cups of coffee a day, with or without caffeine do not seem to harm anyone, but on the contrary have some positive effects. However, in case of pregnancy it is definitely advisable to reduce.  

More interesting facts!

Here is an overview of the caffeine content of various beverages: (1)

1 espresso (50 ml)= 50 mg 

1 cup of filter coffee (125 ml)= 80-120 mg 

1 glass of cola (200 ml)= 13-50 mg 

1 glass of mate (150 ml)= 25 mg 

1 cup black tea (125 ml)= 30-60 mg 

1 cup cocoa (125 ml) = 2-5 mg 

Energy drink (200 ml) = up to 240 mg 

When I talk about a coffee cup, I don't mean the giant 250 ml coffee mug, but the small 125 ml coffee cup.

However, these are only calculated average values. The content is of course dependent on the bean, the roasting and even the machine in which you prepare your coffee. 

If this topic interests you, but you do not drink coffee, then I have something else for you. Of course, I also looked at the topic of tea and wrote an article about it. This follows shortly

I hope this article was helpful for you. Please share it with your friends or post it on Instagram. 

You can also find the article as a podcast on all podcast platforms and YouTube on my channel "Rich Headroom". 

Your Performance Optimizer & Biohacker
Richard Staudner

PS: More performance is available with the basic supplement "100% Performance" from Btonic! There you have everything inside what your body needs for optimal performance, even Omega 3 algae oil. With the code "richard20" you get 20% on your purchase at 

On this website you can also find other helpful supplements for cognitive performance enhancement, but without caffeine. 


1 Hänsel R, Sticher O, Steinegger E, editors. Pharmacognosy - phytopharmacy: with 182 tables. 9th, revised and updated ed. Heidelberg: Springer Medicine; 2010. 1451 pp. (Springer Textbook).

2 Grosso G, Godos J, Galvano F, Giovannucci EL. Coffee, Caffeine, and Health Outcomes: An Umbrella Review. Annu Rev Nutr. Aug. 21, 2017;37(1):131-56.

3, D'Elia L, La Fata E, Galletti F, Scalfi L, Strazzullo P. Coffee consumption and risk of hypertension: a dose-response meta-analysis of prospective studies. Eur J Nutr. February 2019;58(1):271-80.

4. Xie C, Cui L, Zhu J, Wang K, Sun N, Sun C. Coffee consumption and risk of hypertension: a systematic review and dose-response meta-analysis of cohort studies. J Hum Hypertens. February 2018;32(2):83-93.

5 Ramli NNS, Alkhaldy AA, Mhd Jalil AM. Effects of Caffeinated and Decaffeinated Coffee Consumption on Metabolic Syndrome Parameters: A Systematic Review and Meta-Analysis of Data from Randomised Controlled Trials. Medicina (Kaunas). September 11, 2021;57(9):957.

6. Azad BJ, Heshmati J, Daneshzad E, Palmowski A. Effects of coffee consumption on arterial stiffness and endothelial function: a systematic review and meta-analysis of randomized clinical trials. Critical Reviews in Food Science and Nutrition. Mar 26, 2021;61(6):1013-26.

7, Du Y, Lv Y, Zha W, Hong X, Luo Q. Effect of coffee consumption on dyslipidemia: A meta-analysis of randomized controlled trials. Nutrition, Metabolism and Cardiovascular Diseases. November 2020;30(12):2159-70.

8. Poole R, Kennedy OJ, Roderick P, Fallowfield JA, Hayes PC, Parkes J. Coffee consumption and health: umbrella review of meta-analyses of multiple health outcomes. BMJ. Nov 22, 2017;359:j5024.

9. Zhang Y, Zhang D-Z. Associations of coffee consumption with circulating levels of adiponectin and leptin. A meta-analysis of observational studies. International Journal of Food Sciences and Nutrition. Nov 17, 2018;69(8):1003-12.

10 Kondo Y, Goto A, Noma H, Iso H, Hayashi K, Noda M. Effects of Coffee and Tea Consumption on Glucose Metabolism: A Systematic Review and Network Meta-Analysis. Nutrients. Dec 27, 2018;11(1):E48.

11 Sartini M, Bragazzi NL, Spagnolo AM, Schinca E, Ottria G, Dupont C, et al. Coffee Consumption and Risk of Colorectal Cancer: A Systematic Review and Meta-Analysis of Prospective Studies. Nutrients. Mar 24, 2019;11(3):E694.

12. Zhang J, Zhou B, Hao C. Coffee consumption and risk of esophageal cancer incidence: A meta-analysis of epidemiologic studies. Medicine (Baltimore). April 018;97(17):e0514.

13 Ebadi M, Ip S, Bhanji RA, Montano-Loza AJ. Effect of Coffee Consumption on Non-Alcoholic Fatty Liver Disease Incidence, Prevalence and Risk of Significant Liver Fibrosis: Systematic Review with Meta-Analysis of Observational Studies. Nutrients. September 2021;13(9):3042.

14 Srithongkul T, Ungprasert P. Coffee Consumption is Associated with a Decreased Risk of Incident Chronic Kidney Disease: A Systematic Review and Meta-analysis of Cohort Studies. European Journal of Internal Medicine. July 2020;77:111-6.

15. Wijarnpreecha K, Thongprayoon C, Thamcharoen N, Panjawatanan P, Cheungpasitporn W. Association of coffee consumption and chronic kidney disease: A meta-analysis. International Journal of Clinical Practice. 2017;71(1):e12919.

16. Hong CT, Chan L, Bai C-H. The Effect of Caffeine on the Risk and Progression of Parkinson's Disease: A Meta-Analysis. Nutrients. June 22, 2020;12(6):E1860.

17 Kang D, Kim Y, Je Y. Non-alcoholic beverage consumption and risk of depression: epidemiological evidence from observational studies. Eur J Clin Nutr. nov 2018;72(11):1506-16.

18. Ran LS, Liu WH, Fang YY, Xu SB, Li J, Luo X, et al. Alcohol, coffee and tea intake and the risk of cognitive deficits: a dose-response meta-analysis. Epidemiol Psychiatr Sci. Feb. 11, 2021;30:e13.

19 Larsson SC, Orsini N. Coffee Consumption and Risk of Dementia and Alzheimer's Disease: A Dose-Response Meta-Analysis of Prospective Studies. Nutrients. Oct 14, 2018;10(10):E1501.

20. Zhou A, Taylor AE, Karhunen V, Zhan Y, Rovio SP, Lahti J, et al. Habitual coffee consumption and cognitive function: a Mendelian randomization meta-analysis in up to 415,530 participants. Sci Rep May 14, 2018;8(1):7526.

21. Kim Y, Je Y, Giovannucci E. Coffee consumption and all-cause and cause-specific mortality: a meta-analysis by potential modifiers. Eur J Epidemiol. August 2019;34(8):731-52.

22. Li Q, Liu Y, Sun X, Yin Z, Li H, Cheng C, et al. Caffeinated and decaffeinated coffee consumption and risk of all-cause mortality: a dose-response meta-analysis of cohort studies. Journal of Human Nutrition and Dietetics. 2019;32(3):279-87.


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