Caffeine is the most widely consumed psychoactive substance in the world (1), whose rate is steadily increasing. According to one source (2), daily consumption has risen from 9% in 1999 to 41% in 2017- and that’s just in specialty coffee! More broadly, it is reported that over 85% of American adults consume caffeine daily, in the amount of 180 mg, which is akin to about two cups of coffee (1). So what’s the buzz? Is caffeine a productivity superpower or an adrenal draining ultra-drug? While many studies have been conducted on the benefits and health consequences of caffeine, the data remain inconclusive. How is this possible? Well, the effects of caffeine are HIGHLY individual, and depend on potential factors such as brain receptor sensitivity, and the presence or absence of certain genes and metabolic enzymes, which can be further influenced by certain medications, health conditions, and other lifestyle factors such as stress, gut health, and activity level! So let’s dive into the available research and information on caffeine, and empower YOU to determine your ideal caffeine intake.
READY TO DIVE IN?
Caffeine: the basics
Caffeine, or to be scientific, 1,3,7 trimethylxantine, is a naturally occurring substance found in coffee beans, tea leaves, the shrub seeds of yerba mate and gurana, the kola nut, and cocoa (3). In more recent years, it has increasingly been added artificially to foods, beverages, beauty products, and over-the-counter medications (1). It is most commonly ingested, and because it is both water and lipid soluble, it easily crosses the blood-brain barrier, is rapidly absorbed by the small intestine and can be found in most bodily fluids, including: saliva, semen, breast milk, amniotic fluid, and cerebrospinal fluid (1; 4). Most report feeling the effects of ingested caffeine within 10 minutes of consumption, with its peak effect of focus, concentration, alertness (and depending upon sensitivity, perhaps heart palpitations, breathlessness, and anxiety) occurring within 30 to 45 minutes (4). Caffeine is clinically recognized as an addictive substance (Kresser), with corresponding withdrawal symptoms (1). It is recommended that one wean down or off caffeine slowly over time if trying to decrease intake (e.g., 5; 6).
While many feel and enjoy the “buzz” from consuming caffeine, purely defined, caffeine is not actually a stimulant. So how does it do what it does?
Caffeine: molecular structure
The molecular structure of caffeine is quite similar to that of another neurotransmitter: adenosine. Adenosine concentrations parallel neuronal activity (i.e., the more neuronal activity the higher the concentration of adenosine) (7; 8). Once adenosine reaches a certain threshold, it will begin to bind with adenosine receptors, creating a calming, sleepiness effect. That is, unless caffeine comes in! Upon intake, caffeine will bind to the adenosine receptors, blocking the adenosine and thus its calming, sedative effects: vasodilation, lowered heart rate and blood pressure (8; 3). In fact, caffeine’s counteraction of vasoconstriction along with its anti-inflammatory properties is what makes it an effective addition to OTC and prescription pain medications (1).
FUN FACT: - we have adenosine receptors NOT ONLY in the central and peripheral nervous system, but in various organs too (1)- including the kidneys and colon- when caffeine binds to these receptors it triggers the urge to use the restroom (4).
Speaking of restroom- caffeine is a diuretic (it makes ya pee!), and this expedited passing of urine can also increase the release of vitamins and minerals from the body (e.g., potassium, magnesium, zinc, calcium, vitamin c, and the b vitamins) which can increase the risk of deficiency and related symptomatology (e.g, anxiety, panic, mood swings, and fatigue) (9).
Caffeine has a half-life of approximately six hours (again, it depends on individual factors), which means it takes about six hours for the original concentration of caffeine in the body to reach half of that amount. This is one of the reasons people may reach for another cup throughout the day. This is ALSO why drinking caffeine late into the afternoon may be a hindrance to quality sleep later that evening!
Ok, now that we’ve got the basics down, let’s dig deeper into the pro’s, con’s, and most importantly some of the individual factors to consider in your empowered choice to consume caffeine!
Because if its popularity among consumer’s, many of us have already been exposed to the benefits of coffee and caffeine. For thoroughness, let’s briefly review:
caffeine: potential benefits
While there appear to be beneficial relationships between caffeine consumption and reduced risk of decline and disease, the studies are often limited to being of an observational nature with specific population details and thus we cannot conclude causation (i.e., a direct effect) or generalize to all people (including ourselves!). There are also certain populations for whom the literature would suggest caffeine could be harmful.
Let’s take a look:
caffeine: potential risks
Ok, so there’s a snapshot of the big picture when it comes to current research on the benefits and potential harms in consuming caffeine. Feeling any closer to what’s best for you?
If so, great! If not, I completely understand and my hope is that you feel more informed. Research in this fashion can give us an idea of TRENDS as well as potential benefits and harms in CERTAIN POPULATIONS that don’t readily generalize to us as individuals. So, what’s an Empowered Patient to do? Be aware of the research and become your own health detective! What I mean by that is, most likely, we will be best served by honing in on our own current health, lifestyle factors, and tolerance levels to determine the type and amount of caffeine that is best for us right now!
Let’s take a look at tolerance and sensitivity:
caffeine: Tolerance & sensitivity
On average, for “healthy” adults, a daily intake of 200-400 mg (i.e. two to four cups/day) is considered to be “safe” in that it is not associated with adverse health effects (1; 13).
FUN FACT: according to one study (14), the heritability of coffee consumption is estimated to be 50%; there may be a small percentage of the population that carry a gene linked to higher caffeine intake with no adverse risks (i.e. caffeine hyposensitivity).
On the other side of the spectrum, those with caffeine hypersensitivity may experience adverse effects after consuming only a relatively small amount (e.g., 30-50 mg or less) of caffeine. This reaction, which can include symptoms such as heart palpitations, sweating, jitteriness, increased anxiety, insomnia, muscle tension, restlessness, and blood sugar dysregulation (5; 9; 13) is separate from a caffeine allergy (which can be tested and diagnosed). The later is often more severe, and can include: sneezing, hives, itching and hoarseness of the throat, swelling of face, mouth, and throat, eczema, pain in the chest, hyperventilation, confusion, inability to focus, dizziness, mood swings, paranoia, and hallucinations (9).
What are you gathering as you read this?
Are you feeling like you have a pretty good idea of where you fall on the spectrum generally with caffeine tolerance?
Keep in mind that life events such as periods of ongoing stress, chronic illness, HPA axis disregulation (i.e. adrenal fatigue), gut health issues, sleep deprivation, over-training, and the use of certain medications change that! In addition to lifestyle factors, there are certain genetic and metabolic factors that can influence our caffeine tolerance.
Additionally, there are specific genetic and metabolic factors to consider:
Caffeine: genetic & metabolic considerations
The CYP1A2 is the gene that codes for the enzyme primarily responsible for metabolism of caffeine in the liver (1;5). This gene appears to have a large genetic variability (1;14); it is reported that approximately 50% of the population has a variant of the CYP1A2 that leads to slower metabolism of caffeine (5). It may be that those who feel hypersensitive to caffeine consumption produce less copies of the gene that clears caffeine from the system and therefore, experience heightened, prolonged, and adverse effects (5; 6; 8; 13), although some of the adverse effects have been reported in slow metabolizers (5).
FUN FACT: the CYP1A2 gene is expressed in a circadian rhythm (and thus caffeine will have a different impact at different points in the day), and is the same enzyme that metabolizes steroid hormones (1). The impact is that steroid hormones SLOW the metabolism of caffeine; this is why the half-life of caffeine increases in pregnant women (up to 16 hrs longer!) and in women taking oral contraceptives (it tends to DOUBLE!). If you are interested in learning more about your genetic variations as they relate to caffeine consumption, there are tests available (i.e. 23andme).
So we've taken a pretty extensive look at CAFFEINE... but what about those of us who know we are sensitive/prefer to consume DECAF?
Here are just a FEW Things to consider:
If it is an issue of caffeine sensitivity, decaf may be the way to go (with approximately 2 mg per serving in coffee)- opt for Swiss-water-processed decaf if you can! Keep in mind, with coffee, that even decaf retains its diuretic properties, the proteins that often cross-react with gluten, and acids that can alter cortisol and thus blood sugar regulation (6). Again, this is not true for everyone, just data that can ground your own experience.
Alright, that’s it for now! As you can see, there is A TON of available and sometimes conflicting information out there on caffeine and coffee consumption. As an Empowered Patient, it really comes down to awareness and paying attention to our own experience over time.
Now, I’d love to HEAR FROM YOU!
How was your journey through this information?
What did you learn?
Are you a hyper-responder? Hypo-responder? Land somewhere in-between?
What aspects are you most interested in? Have you taken genetic/other tests? Did you find them helpful/informative?
How are you going to consume caffeine going forward?
PLEASE SHARE YOUR COMMENTS BELOW!!
Here to support you along the way!
Your Health Advocate,
P.S. If you have a question or would like a deep dive on a specific health/wellness topic and would like me to cover it in this series, please email me at : firstname.lastname@example.org