INTRODUCTION
Disclaimer: this document is not an argument for or against coffee.
I drink coffee every day, and have also fully incorporated it into my health and longevity protocol: "Life Override".
Amid all this "noise" we hear on social media, mainly generated by influencers and other health and nutrition "coaches", I wanted to bring a little music: better-verified information, more nuanced and balanced, accompanied by a less common point of view: that of the biohacker.
Coffee is one of the most widely consumed drinks in the world. According to the various estimates I was able to compile as I write this article (May 2025), about 1.7 billion people drink it every day (nearly 2.4 billion with occasional consumers).
There are more than 20,000 scientific studies on coffee, and that number is only increasing.
These studies cover a wide range of areas:
- 🧬 Effects on health (cardio, liver, metabolism, cancer, neuroprotection, etc.)
- ☕ Bioactive compounds (caffeine, chlorogenic acid, diterpenes, etc.)
- 🌍 Social and economic aspects
- ⚗️ Production, roasting, extraction and the chemistry of coffee
Most of the studies in the first category generally show a convincing association between coffee consumption and various health benefits (longevity, cardiovascular protection, antioxidant effect, etc.).
These are most often summarized by "drinking coffee is good for your health", or by general recommendations such as "drink coffee". But, as in everything around us, coffee conceals a more complex and more nuanced reality. Indeed, our response to coffee is in practice highly individual and determined, in part, by our DNA.
🧬 CYP1A2: the gene that decides whether coffee does you good… or not?
Although it is not the only one, the most active component of coffee is caffeine: a psychoactive molecule whose effects vary enormously depending on how quickly the body eliminates it.
CYP1A2 is the gene that codes for a liver enzyme technically called "cytochrome P450 1A2" and that is most often abbreviated as… CYP1A2 (yes, the same name as the enzyme that codes for it: that does not exactly make it easier to understand).
This enzyme is responsible for about 95% of the metabolism of caffeine, which it mainly converts into paraxanthine (80%), as well as into theobromine (10 to 12%) and into theophylline (4 to 5%): three metabolites with distinct psychological effects.
This metabolism process takes place mainly in the liver and can vary considerably from one individual to another, notably because of genetic polymorphisms. The most studied is rs762551, located on the CYP1A2 gene.
Each individual inherits two copies of each gene (one from each parent) and there are three possible genotypes at this location:
- ⚡ AA: both copies of the gene carry the A allele → fast metabolizer
- ⚖️ AC: one A copy, one C copy → intermediate to slow metabolizer
- 🐢 CC: both copies carry the C allele → slow metabolizer
People with the AA genotype produce a more active CYP1A2 enzyme: caffeine is eliminated more quickly, which limits its prolonged effects.
Conversely, AC or CC individuals have lower enzyme activity, prolonging the presence of caffeine in the body.
I am simplifying, with a few shortcuts, but do not forget that nothing is that simple in nature. Thus, in reality, this polymorphism is not the only factor in play. Other genes also influence the rate of metabolism and the effects we feel.
These include:
- 🔬 AHR (Aryl Hydrocarbon Receptor) regulates the expression of CYP1A2
- ⚙️ POR is a key cofactor of the P450 enzymes, including CYP1A2
- 🚪 ABCG2 modulates the intestinal and hepatic excretion of xenobiotics, including caffeine
- 🧩 PDSS2 is associated with modulation of the perceived need for coffee (less active = more frequent consumption)
In plain terms: caffeine metabolism is not "just" binary (slow or fast), but a polygenic continuum, also influenced by environment, diet, the microbiota and lifestyle. But, to make things understandable, it is sometimes necessary to simplify.
Important: rs762551 is a useful indicator, but not a deterministic one. In practice, the environment, hormones and certain co-medications can speed up or slow down CYP1A2 so much that the observed "phenotype" (what you feel) can differ from what the genotype suggests.
✅ Coffee does you good!
Studies show that fast metabolizers (AA) generally derive clear benefits from coffee. Examples include:
- ❤️🩹 A 15-20% reduction in cardiovascular risk
- 🩸 A dose-dependent reduction in the risk of type 2 diabetes
- 🧠 A 17% reduction in the risk of stroke
- 🧓 A reduction in the risk of dementia
There are dozens of other examples with more or less similar benefits and figures among the thousands of studies available
If we considered only these individuals, we could simply conclude that "drinking coffee is good for your health", but…
⚠️ Specific risks for slow metabolizers
If you are an AC or a CC, that is a slow to intermediate metabolizer, then high caffeine consumption can significantly increase certain long-term risks.
That is what a recent study notably shows (PMC9880799), carried out on hypertensive adults, slow metabolizers who consumed more than 3 cups a day. This consumption was accompanied by significantly increased risks:
- 🧪 2.7x more albuminuria (kidney damage)
- 💧 2.1x more renal hyperfiltration
- 🩺 2.8x more arterial hypertension
But that is not all!
🧠 ADORA2A: the effect of coffee on the brain
ADORA2A (Adenosine A2A Receptor) is a gene that codes for the adenosine A2A receptor, a G protein-coupled receptor (GPCR). It plays a central role in several key functions of the body, notably:
- 🔥 Regulation of inflammation
- 🛡️ Modulation of the immune system
- ⚡ Dopaminergic transmission (motivation, pleasure, vigilance)
- 😴 Regulation of sleep
What ADORA2A does
- ⚙️ Modulation of dopamine (involved in Parkinson's, schizophrenia and addictions)
- 🧬 A role in immune modulation (it dampens certain activation signals depending on the context)
- ❤️ A vascular and cardiovascular role (vasodilation and protective effects depending on the context)
- 💤 A direct impact on sleep and vigilance
Caffeine acts as an antagonist of ADORA2A. It blocks this receptor, which prevents adenosine (the messenger of fatigue) from taking effect. The result: we stay awake, alert, "dopamine-boosted". But once again… that is not true for everyone!
Depending on our genetic variation, the effect can be very different. Some people will:
- ✅ Tolerate caffeine well and get a gentle mental boost from it
- ⚠️ Be hypersensitive, with anxiety, palpitations, or sleep disorders
- 😴 Paradoxically fall asleep after a coffee, a calming effect in some profiles
Depending on the genetic variant of ADORA2A, caffeine can therefore have a calming or an anxiety-inducing effect. This genetic polymorphism explains why one and the same espresso can soothe a person or, on the contrary, wreck their evening (and their sleep!)
🧯Aggravating or moderating factors
All of that is interesting, but still incomplete: indeed, there are many other factors that can influence all of this further, including for example:
- 🚬 Tobacco: speeds up CYP1A2
- 🍊 Grapefruit juice and cocoa: can modulate the metabolism of certain xenobiotics and indirectly influence tolerance in some profiles
- 😵💫 Chronic stress: can inhibit CYP1A2 via hormonal effects
- 🦠 Intestinal microbiota: can modulate a significant part of how caffeine is processed, with substantial variation between individuals
But also age, pregnancy, liver function, diet, etc., which can influence its metabolism.
I know, this is starting to be a lot…
🛠️ The biohacker's approach
As a biohacker, the aim is to take an analytical, measured and individual approach.
- 🧬 Analyze your genome (CYP1A2, ADORA2A) (useful indications, but probabilistic, and they require perspective and nuance)
- 👀 Observe your reactions (sleep, heart rate, anxiety, etc.)
- ⚖️ Adjust your coffee consumption (dosage, timing…)
- 🌿 Explore the alternatives and the combinations (decaf, rhodiola, matcha, ginkgo, L-theanine, etc.)
☕️ Coffee: preparation and culture
We have just seen how biological, metabolic or genetic factors affect the health impact of coffee consumption differently for each individual, but the complexity does not stop there.
Not all coffees are equal, and the preparation method also strongly influences both the quantity of caffeine and the presence of cafestol and kahweol, two compounds naturally present in coffee oil that can increase LDL (the "bad" cholesterol) if they are not filtered.
Thus, filter coffee will trap the diterpenes and its impact on cholesterol will be negligible, whereas an espresso may cause a slight elevation at high levels of consumption (doses and extraction vary with country and habits).
However, French-press coffee is more likely to cause a measurable increase in LDL if consumed regularly, and let us not even talk about "Turkish coffee", for which the effect will be greatest.
Finally, the cultural habits linked to coffee consumption strongly influence the results: in Italy or in Ethiopia, coffee is a social experience with doses that are often smaller and more spaced out. An Italian espresso is often shorter (ristretto/espresso), but the caffeine per "shot" varies enormously according to the dose, the blend and the extraction. In practice, an espresso can range roughly from ~30 to ~90 mg per cup. Conversely, a large mug of filter coffee often contains more caffeine overall.
As a result, the number of coffees per day is an unreliable measure from one country to another.
💤 Sleep: the real deciding factor
You can "no longer feel" the caffeine and yet still be harming your sleep (latency, micro-awakenings, deep sleep). The biohacker's point: define a strict cutoff time, then adjust it according to your metrics (falling asleep, awakenings, HRV, mood).
Pragmatic tip: if your sleep is a priority, and it is not going well, test a "cutoff" at day −7, 8 to 10 hours before bedtime, then gradually reintroduce it if everything stays stable.
🎯 Dose: think in mg, not in "cups"
We talk about cups of coffee, as I did earlier, but biohacking starts when we move beyond vagueness: "a cup" is not a reliable unit. Between espresso, filter, cold brew and mug sizes, the real exposure varies by an enormous factor.
Simple approach: calibrate your dose (in mg) and identify your "minimum effective dose" (useful stimulation with no crash and no impact on sleep).
🔁 Tolerance, dependence, withdrawal: the adenosine loop
With regular consumption, the body adapts (adenosine receptors). Result: the perceived effect drops, the dose rises, then withdrawal becomes brutal (fatigue, headaches, mood).
Biohacker strategy: cycle. Not everyone necessarily needs it. For those who do, designing cycles (example: reduce to the minimal dose on weekdays and do a light "reset" on the weekend, or plan periodic tapering phases) can be an excellent option. Objective: keep the useful effect without escalation.
❤️ Cardio: acute effects vs chronic effects
Two realities coexist:
- Acute effect: a possible rise in blood pressure and heart rate, especially in people unused to it or sensitive to it.
- Chronic effect: in many cohorts, moderate consumption is associated with lower mortality, and part of the signal also exists with decaf (which points toward compounds other than caffeine).
The biohacker's point: the individual takes precedence over the crowd. If you have borderline blood pressure, palpitations, or a tendency toward anxiety, measure your blood pressure morning/evening for 7 days with and without coffee, rather than believing the results of a population average.
🍬 Metabolism and blood sugar: especially on an empty stomach
In some people, coffee (especially on an empty stomach) can amplify the stress response (adrenaline/cortisol) and disrupt blood sugar or hunger. In others, it is neutral, or even beneficial. The variability is enormous.
Biohacking: if you have a glucometer, compare coffee on an empty stomach vs coffee with breakfast vs coffee after a meal, over 3 days. You will have *your* truth, not social media’s.
🧲 Iron and micronutrients: the invisible trap
Coffee can inhibit the absorption of non-heme iron (the kind found in plants and many mixed meals). If you have borderline ferritin levels or are prone to anemia, this is an important parameter to take into account.
Simple heuristic: keep coffee/tea 60 to 90 minutes away from a meal rich in iron (or an iron supplement).
🧪 Coffee quality: contaminants, molds, pesticides
The "biohacker" point too often ignored: quality and the supply chain (storage, freshness, roasting, sourcing) can count as much as genetics. Mycotoxins and contaminants exist, but the subject is also a breeding ground for aggressive marketing.
Pragmatic approach: favor freshness, a reputable roaster, traceability, clean storage. And, if you are very sensitive, test a change of source before concluding that "coffee" is the problem.
⚗️ Decaf: not just "coffee without caffeine"
Decaf keeps a large part of the bioactive compounds other than caffeine, which explains why certain health associations can persist.
The biohacker's view: if you like coffee but your sleep suffers or your anxiety worsens, decaf (or a "half-caf") can be the optimal compromise.
💊 Drug interactions: the safety aspect
Caffeine and CYP1A2 interact with certain medications and hormonal contexts. If you are taking medication, a change in coffee dose can sometimes change the effects you feel (anxiety, palpitations, insomnia), and the reverse is true as well.
The biohacker's point: if you are taking medication, pregnant or have liver disease, consider coffee as an "active molecule" and not as a mere neutral drink.
🧠 N=1 biohacking protocol in 7 days
- Day 1-2: coffee only in the morning, strict cutoff, measure sleep (latency, awakenings) + blood pressure + how you feel.
- Day 3-4: same dose, but test coffee with a meal vs on an empty stomach.
- Day 5-6: replace with decaf, keep the ritual and the timing identical.
- Day 7: choose your "setpoint" (minimum effective dose + cutoff) and hold it for 2 weeks before concluding.
🧾 In conclusion
Coffee is neither a universal remedy, nor a poison for everyone. But knowing your genome, your microbiota, and listening to your physiological signals, etc., makes it possible to turn it into an effective tool for both health and day-to-day performance… provided you avoid a dogmatic approach and adapt your consumption to your individual situation.
Share your experience in the comments! I will keep updating this page over time. Take care of yourselves and your loved ones. Have a great weekend!
Christophe CasalegnoFind all my social links at: all.bo
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