My love for caffeinated drink (specifically coffee) started after university when I discovered its amazing effects on my cognition (it allowed me to not only stay awake, but REALLY awake, it felt like my brain was running on steroids). After decades, my love for it still remains, but I've learned to tinker with it according to:
1. My energy level (basically how I feel cognitively and physically)
2. My diet
3. My sleep quality from the previous night
4. My plans for the day
To say that I've completely grasped the effects of caffeine is a complete lie, I also question those who claim they have unlocked the perfect dose for caffeine ingestion, or perfect dose for any chemicals for that matter. However, I think there are things about caffeine that most people don't understand, and I hope I can shed some light on that.
Let's start with the bad, since most of the social media information about caffeine these days are negative (for good reasons, because I do think people are drinking coffee under the wrong circumstances..). To understand why caffeine may be affecting your health in a negative way, we'll look at 2 popular effects it has on the body:
1. How it keeps us awake
2. How it affects our stress hormone
How does caffeine keep us awake?
To understand how caffeine keeps us awake, we have to look at the chemical adenosine. Many people have heard of ATP (adenosine triphosphate), and understand that ATP is an energy currency in our body that allows us to move, talk, think, eat, digest, etc.. It basically is the currency in our body that keeps our cells running and thus, keeps us alive. As we go on about our regular day, we also expend more and more ATP, which through a complicated process, can eventually breakdown into adenosine (energy is created by the cleavage of phosphate groups).
Adenosine can have multiple different effects depending on the type of receptor it attaches to, but one of the global effects of having too much adenosine build up in the brain is that it creates sleepiness (it builds your sleep pressure). Adenosine is usually cleared and recycled during sleep by the cerebral spinal fluid, that is why if you do not have adequate sleep, your sleep pressure can be tremendously high and cause you to fall asleep behind the wheel (really... really bad). So what does caffeine have to do with all this adenosine talk? Well, caffeine is extremely similar in its chemical structure to adenosine, and competes with adenosine receptors (think of adenosine and caffeine playing musical chair..), but it doesn't activate the receptor it binds to (in science that is called an antagonist). So a typical receptor that is bound to adenosine will create sleepiness, and when caffeine wins the race to the chair, it just sits there can like a rebellious kid, not accepting any responsibilities (which by the way is also why most people may "crash" once caffeine wears out in your system, because now adenosine, like a responsible adult, will not stop until it bind and activate all its receptors).
So why is this bad? It is still unclear as to the exact long-term effects of caffeine will do to these receptors, but from what we understand about the body is that it is an extremely smart system. An increase in demand leads to an increase in supply, meaning more caffeine, more adenosine receptor. Our body starts to create more and more receptors to meet the demand. That means more chairs available for adenosine to sit on, and you will need to drink a heck of alot more caffeine in order to block that adenosine from binding to its receptor. This becomes detrimental because of 2 reasons (that I've figured out anyway...i'm sure there are more reasons):
1. It will affect your ability to fall asleep when you need to
2. Increased caffeine means more adenosine build up in the brain, and more clearance required by the cerebral spinal fluid
Essentially, it becomes a vicious cycle of: feeling sleepy --> coffee --> still not quite awake --> more coffee --> finally feeling a little more awake --> but its 6pm --> having a hard time falling asleep OR/AND falling asleep fine but brain is busy clearing adenosine instead of doing all its other wonderful stuff --> waking up feeling sleepy because there are still adenosine present.
How does caffeine affect our stress hormone?
Stress is crucial in allowing you to become stronger, physically, mentally, and immunologically (not sure if that's even a word). Our nervous system can be generalized into 2 different categories: sympathetic nervous system (fight or flight) and the parasympathetic nervous system (sleep and digest). The reason stress is important is because it activates our sympathetic nervous system, which allows us to become vigilant, increase heart rate and blood pressure, and free up stored glucose so we are readily able to contract our muscles when required.
Caffeine can readily activate the HPA-axis (hypothalamic-pituitary-adrenal axis) which results in an increase in adrenaline and cortisol, which is responsible for everything that is mentioned above. Most people have heard of cortisol, and it's gotten quite a negative connotation to it, but it's not all bad. In fact, in a healthy body, our cortisol level goes through a circadian rhythm, where it goes on a steady rise the minute we wake up (or even before we wake up) and peaks around 1-2 hours after awakening (reasons are not clear, but speculation is on our ability to be vigilant for the start of the day, and to better cope with the our perception of the world. I mean..makes sense given that we used to need to fend ourselves from lions and tigers the minute we wake up, not to mention snakes, scorpions, spiders...).
So here's my question, if our body naturally produces cortisol (meaning our sympathetic nervous system is active) during awakening, and peaks around 1-2 hours after awakening, why should we be drinking caffeinated drinks upon awakening? Here's the paradox: people who drink coffee in the morning because they don't feel restful are actually the ones who SHOULD NOT be drinking coffee at all. You don't really want to add stress upon stress..but unfortunately, most people who consume caffeinated drinks are the ones who are under either an acute or chronic stress (stress defined as either a self-perceived or a measurable activity such as exercise).
One may ask, what's wrong with having too much cortisol in our system? Our body is in a constant state of maintaining homeostasis, if there are too much of anything in our body, we tend to have a gate way of controlling these chemicals so it doesn't alter that homeostatic response. So if we have too much cortisol in our body, what usually happens is that we go through a negative feedback loop where cortisol will shut off the HPA-axis, hence decreasing adrenal gland activity. BUT, if you are pounding stress upon stress, this cortisol is maintained in a high level and will start to dysregulate this feedback loop, medically this is called cortisol dysregulation. I'll use the example of exercise to make this a little easier to comprehend: exercise creates stress in our system, it creates microtears in our muscles, and induces local inflammation. This is great, because once we recover from these alert stages of stress, we eventually adapt, that is how we get stronger, and bigger, and faster. If we however overreach and not allow our muscles to recover properly, we break down, and get injured. Same thing occurs internally when we have cortisol dysregulation, in fact, it has a potential of creating metabolic problems like diabetes, and alter your mental state (sympathetic nervous system inactivates the prefrontal cortex, which is responsible for our emtional regulation) and pose threat on the development of depression and anxiety issues.
So yea..it has the potential to make things very bad for us, but to create a perfect storm, it is time-dependent and dose-dependent. In other words, drinking large doses of caffeinated drinks under conditions when your body is under chronic/acute stress can be a recipe for disaster if done chronically.
Alright, so now that the bad news is out of the way, what is good about caffeine? If we look at epidemiological studies (not reliable at all..but provides insights), countries and populations that readily drink tea and coffee also have lower risk of death from any causes (like I said..insights, not causative at all..). This brings up some questions regarding possible ingredients in coffee and tea that be potentially beneficial for the human body. It turns out, that these type of caffeinated drinks are high in polyphenols, mainly phenolic acid and flavonoids. These are the chemicals that are readily found in vegetables we eat and one of the main ingestible antioxidants in our diet. So let's break down some of this information to better make sense of how drinking coffee may be beneficial when done right. I'll explain 2 things that I am comfortable sharing:
1. What antioxidants actually do?
2. How much polyphenols are in coffee in comparison to berries?
To understand what antioxidants do, we have to look at something called oxidative damage. We hear terms like free radicals and oxidative stress, and understand that having too much of either can result in things like cancer. So what is oxidative stress? Our body is an walking biochemical lab, and we are going through chemical processes every second of our lives, even when we sleep. Take something as simple as breathing for example, the reason we breath is to take in oxygen, because our cells' livelihood depends on it. Without oxygen, our cells will not be efficient in providing energy to fuel our system, and hence enter a process of programmed cell death. With oxygen, cellular respiration is available, and each of our cells will be able to provide much more energy (ATP) than if we do not. While going through this chemical process (called oxidative phosphorylation) of providing our body with an abundance of energy fuel, the cell (mitochondria of the cell) also creates alot of by products called reactive oxygen species (a form of free radicals).
These reactive oxygen species come in the form of peroxides, hydrogen peroxides, superoxides, hydroxyl radicals etc. The reason why these are dangerous is because they are highly reactive (hence...reactive oxygen species, sometimes science does make sense through their terminology), meaning that they can readily bind or react to other things like protein, lipid (mainly polyunsaturated fatty acid, yes..PUFAs are not always good in large amounts, it highly depends on whether you are under oxidative stress or not), and DNA/RNA and change their chemistry (usually in a bad way because it causes destabilization of the molecule itself).
In a normal functioning body, homeostasis takes care of much of these free radicals because of the presence of antioxidants. As the name implies, antioxidants are great for us because its sole purpose is really to scavenge these highly reactive free radical and stabilize them. How do we produce these antioxidants you may ask? We create alot endogenously (meaning our body creates them from within), things like glutathione, Coenzyme Q, Ferritin, Alpha-lipoic acid, uric acid, etc. and the creation of these antioxidants is really really...really..complicated, but what you need to know if much of its amount depends on our diet (we need help from exogenous sources to create endogenous antioxidants, for those of you nerds who really wanna know how endogenous antioxidants are produced, heres a paper about glutathione (here).
So if we create it in our body and our body is such a smart system, why do we need to worry? Well...I'm gonna try to keep it simple so that I don't dig myself into a rabbit hole. To keep it simple, the world we live in now just creates too much problems in our body that endogenous antioxidants may not be able to keep up with its overwhelming demands (the chicken we eat has alot of steriods and antibiotics than before, the fish we eat contains more mercury, some vegetables we eat contain more chemicals than nutrients due to the fertilizers we use, the sun we love has much more UV rays than before due to the damaged ozone layer, i mean..i can probably go on and on). For these reasons, exogenous intake becomes key, that's why we are encouraged to take in things like vitamin A, vitamin C, vitamin E, and polyphenols because they help us create antioxidants.
So now that we roughly understand why antioxidants are important, how much polyphenols does coffee and tea actually contain? For simplicity purposes, I'll just focus on coffee (because I'm biased). This is again, a very nuanced topic, because it highly depends on:
1. type of coffee beans
2. how the beans are roasted
3. how long it's been on the shelf after roasting
Annnnnnd, here's your answer:
1. organic coffee > non-organic
2. light > dark roast
3. non-organic coffee lost its bioactive compounds after 12 months of shelf-life
I'm not gonna get into the how and why because...it's beyond my understanding, but those of you who would like to know, here's a good paper on it (here). The exact amount of daily intake of polyphenol is still yet to be determined, mainly cause its just very hard to grasp an RDI (recommended daily intake) in general unless we go through another war (let's hope not). Let's just put things in perspective though, if you google the amount of polyphenols in something simple as blueberry, it contains 5.6mg/g. In a conventional coffee that you buy out doors, or even brewed from home, you're looking at around 41mg/g for a light roast coffee bean. So a typical coffee is about 175ml which usually amounts to about 10.6g of coffee bean, if you do the math, that's about 436mg of polyphenol ingested. A bowl of blueberry is usually around 100g, and if you do the math for that, its about 560mg of polyphenol. Now coffee drinkers usually take in about 2 cups of coffee, that's 872mg of polyphenols in the body. If you ask me, that's a damn lot...In countries like Norway and Finland, they figured that coffee provides about 64% of total ingested antioxidants. So yes...there is something good about caffeinated drinks like coffee.
Sooooooo... now what? How much coffee is the right amount? Here's my answer:
Like everything else, these things are always time-dependent, circumstantial, does-dependent, and what most people don't realize, Gene-dependent. Nutrition and what I consider as natural psychoactives, such as caffeine, is way too individualized, and the only way to know the right amount for yourself is:
1. educate yourself on what it actually does to the body
2. constant tinkering
3. diligent documentation
4. genetic testing
If it is at all helpful, I will include a few pointers that I use for myself to gauge the amount of coffee I drink during a typical day:
- wake up feeling tired = maaaaybe 1 cup of coffee depending on how I feel an hour after awakening
- wake up feeling exhausted = no coffee, take in antioxidants from other food sources
- wake up feeling refreshed and energized = take in 1-2 cups of coffee, I also try to hit a prime workout day, which gives me more reason to need to fight these oxidative damages
- busy day at work, or need to use alot of brain power? Definitely drinking at least 1 cup of coffee, this is on the contingency of me having a good night sleep
- Low HRV (heart rate variability) + high RHR (resting heart rate) = definitely no coffee for the day
- Low HRV + low RHR = 1-2cups of coffee
- High HRV + low RHR = 2 cups of coffee
- High HRV + high RHR = maybe a cup
- eating alot of crappy food + feeling really rested and energized = a cup of coffee
- eating alot of crappy food + feeling crappy (not a good recipe for health..) = no coffee
As you can see, it really depends on multiple factors, and I have excluded in my opinion one of the biggest determinant of it all, which is your genetics. Personally, I have a genetic make up that allows me to metabolize caffeine relatively well and quick, so I know that it doesn't stick around my system for long. That is why I am comfortable with drinking as much as 2 cups of coffee a day. (Click here to learn more about how to test your genes).
Now I can't stress enough how simplified this is, but the idea is to provide some general understanding of what caffeinated drink does to your body. The goal is to help you gain more insights on this topic, so you can make informed decision towards better health and recovery strategies.