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Caffeine – All You Need To Know

Ever wondered how caffeine actually works, or if it’s good for you… or how much of it is SAFE!? Here is our quick 521 guide to all things caffeine. 

Caffeine, as a stimulant, has been a part of our lives for thousands of years. From monks saying that drinking green tea allowed them to meditate endlessly without needing sleep, to Coca Cola replacing cocaine with caffeine (not a fair swap… but given the market price of cocaine it’s probably for the best), it’s pretty prevalent and lots of people will wax lyrical about how it’s trying to get you! But is it all that bad??? (… the caffeine, not the cocaine)

521 - Caffeine Structure


• Caffeine is the most widely consumed psychoactive compound in the world

• Less commonly known as 1,3,7-trimethylxanthine

• It acts via the central nervous system (a central nervous stimulant)

• The mean caffeine intake for over 21’s is about 300mg

• Over 95% of caffeine intake is from caffeinated drinks (mostly coffee, but also tea and carbonated drinks)

•  400gm of caffeine daily is deemed to be safe for most 

•  Caffeine takes anything from 3-7 hours to leave the body, depending on how well you metabolise it (it has an average half-life in the body of about 5 hours) 

•  Smokers metabolise caffeine more quickly than non-smokers (by about 50%) 

• Pregnancy (and the contraceptive pill) can slow the metabolism of caffeine significantly

• Many articles have recently cited a link between caffeine and adolescent obesity, though this seems somewhat erroneous as the studies actually showed that increases in consumption of soda like beverages (which contained caffeine) caused an increase in levels of obesity, and no direct link with caffeine was noted.

• While high levels of caffeine intake may not pose many of the risks mainstream gurus purport, some studies are now showing that high caffeine consumption WHILE PREGNANT can substantially increase the risk for obesity in the child, so it is still best to limit caffeine consumption during pregnancy.

General caffeine guidelines for adolescents is 2.5mg/kg bodyweight (100mg for a 40kg child)

• Drinking caffeine in moderation will not force your body to become dehydrated


 NOTHING in this article (or on this website for that matter) is intended for use in the diagnosis or treatment of ANY medical issue. Please see a doctor (or health care professional) if you have any medical problems and take your health seriously! Now let’s take a look at what we can learn from Caffeine (it’s actually quite a bit!)…


The Mechanisms of Caffeine

Caffeine, a methyl-xanthine, is a stimulant (much like other methylxanthines – Theobromine, Theophyllin and Paraxanthine) and is metabolised in the liver into the 3 aforementioned “methylxanthines”. It is both water and fat soluble, and as such can cross the blood brain barrier (hence caffeine’s ability to make us more alert). It primarily works by blocking the action of adenosine. Adenosine is a CNS inhibitor, and a very important molecule that shifts the body towards a more restful (drowsy) and recuperative state. Adenosine is also a rather ingenious self regulating mechanism. Our body’s energy comes from ATP (ADENOSINE-triphosphate). As our body uses energy throughout the day, more and more ATP is used and more adenosine accumulates and attaches to adenosine receptors, meaning we get drowsy and need to rest. So, you can see why physical activity is so important!

Caffeine, by binding to the adenosine receptor (and therefore blocking the adenosine) causes a double reaction:  reduced adenosine binding/activity and increased dopamine activity.

By binding to the adenosine receptor, there is less active adenosine (adenosine that has bound) and therefore less drowsiness. Also, some of the adenosine receptors are complexes that have both a receptor for adenosine AND for dopamine. The caffeine, by attaching to the adenosine receptor increases the propensity of dopamine to attach to its respective receptor. Therefore, increased caffeine means increased dopamine activity.  ADDITIONALLY, caffeine (by blocking adenosine from attaching) increases the amount of Acetylcholine released (an important neurotransmitter).


Health Benefits

Caffeine is mainly comprised of anti-oxidants which therefore can help neutralise some free radicals. It is metabolised in the liver into 3 di-methyl-xanthines: Paraxanthine (increases…), Theobromine (dilates blood vessels, makes you pee more), Theophylline (relaxes the bronchi muscles, though is obtained in very low levels through caffeine metabolism). One of the few things that contains caffeine, theobromine AND theophylline is the drink Yerba Mate which has a caffeine level in between tea and coffee (approx. 85mg per cup).


Caffeine and your Brain

Seeing as caffeine can cross the blood brain barrier, it has shown to have some neuro-protective properties, and can help reduce the risk of both Alzheimer’s and Parkinson’s disease. For Alzheimer’s it is believed to be due to caffeine’s ability to reduce Abeta levels (Amyloid-Beta levels), and is thought to be due to caffeine itself as opposed to one of its metabolites. For Parkinson’s it seems that caffeine offers neuroprotective benefits against the degeneration of the dopaminergic neurons, as well as helping improve motor skills (by blocking the A2a Adenosine receptors), though studies don’t seem to have been long enough to tell whether or not the natural tolerance developed to caffeine would negate the benefits. More research needs to be carried out. 

Caffeine and your Weight

Caffeine can increase Basal Metabolic Rate and as such increases overall daily caloric expenditure. One of caffeine’s metabolites (Paraxanthine) can increase the body’s rate of lipolysis (metabolism of fat), meaning that caffeine can be a potent weight loss tool, though should only be administered as such by a professional.

Caffeine can also reduce the risk of becoming Diabetic, THOUGH it may exacerbate the glycemic response (in postprandial measurements) so can be dangerous for those who already have diabetes. Effectively, it seems that those who regularly drink coffee will develop a tolerance to the negative aspects (increased blood glucose and reduced insulin sensitivity) but maintain the benefits (increased adiponectin, which helps regulate glucose levels, and liver function).

Caffeine and your Heart

Caffeine can help with CAD (coronary artery disease) which was seen in studies when approximately 3-400mg of caffeine was consumed daily. This study was done with coffee and found that at 3-5 cups a day it was protective, and that at anything above 5 cups a day it progressively increased the risk.

Caffeine and Sports Performance

Caffeine has shown in numerous studies to be a potent sports aid, so potent, in fact, that it at one point was in line for being banned as a performance enhancing aid, though this was found to be unfeasible given its prevalence.

It can improve reaction time, power output, aerobic capacity, endurance, and even sprint performance.

Combined Effects

Caffeine combined with L-Theanine (as found in green tea) has shown to have synergistic effects for focus, task switching, and attention. It is also regularly combined with other “focus” nutrients in energy drinks, such as taurine, ginseng, guarana (which is effectively just more caffeine), and certain B-vitamins. 

*The opposite is true for alcohol, which can reduce the negative effects of caffeine without the caffeine reducing the effects of alcohol. What this means is that if you drink caffeinated alcohol you won’t get jittery, you will get just as drunk, but you will have slightly better motor control and focus allowing you to drink even more (and potentially overdose on caffeine AS WELL AS alcohol). The most common cause of caffeine related hospitalization is combining it with alcohol, which is the same when any stimulant is combined with alcohol. 


Potential Problems

As is unfortunately often the case, the dose makes the poison. So, with caffeine, if you take crazy high amounts there can be serious health implications. The level of toxicity is set in and around 10 grams (between 50-100 cups of coffee, depending on strength and size), which no normal person will ever come close to consuming. That said, in 2010 a British man, who apparently did not understand that caffeine had a toxicity level, ate two whole spoonfuls of powdered caffeine and washed it down an energy drink afterwards did not survive. Though instances like this are very rare, any supplement that is measured in milligrams should be handled with caution. 


Caffeine and your Bones

There is also the potential for leeching of calcium and magnesium beginning at around ¾ of a gram (daily) consumption, but give that the mean intake is around 300mg, and even diehard coffee drinks won’t usually go above 5-600mg a day, this shouldn’t be a problem for most.

Caffeine and your Heart

Caffeine can increase blood pressure by causing vasoconstriction, which is why those with heart conditions should reduce caffeine consumption and never consume high caffeine energy drinks prior to exercise. It is also believed that prolonged consumption of high levels of caffeine can lead to arterial stiffness (though this hasn’t been directly studied using caffeine, it is believed to occur due to the fact that coffee chronically raises systolic – not diastolic – blood pressure, which can lead to arterial stiffness).

Caffeine and your Adrenals

Caffeine has shown in studies to increase Cortisol levels (through adrenal signalling), which obviously over time can cause stress on the adrenal glands. While it is evident that excessive stress on the adrenals can lead to lower concentrations of Cortisol being released, the exact impact of this is unclear. Cortisol is an important stress hormone and has a steep increase in production in the early morning to get us ready for the day. Some will tell you that excessive caffeine will reduce your morning concentrations of Cortisol, leaving you feel groggy (hence needing a cup of coffee), BUT a 2005 study found that morning caffeine had no effect whatsoever on Cortisol levels and was only mildly effective at raising Cortisol levels in the afternoon. It’s not a lot to go on, but one thing is clear: excessive caffeine can stress the adrenals. This means that if you are having a stressful period in your life, it’s probably better to reduce stress (think time in nature, meditation, “zoning”, etc.) rather than use caffeine to cope with this stress so as to avoid overly taxing your adrenals (which will already be working overtime to deal with life/work stress).

If, on the other hand, you’re not prone to stress and just love a cup of tea or coffee, then enjoying a few cups a day won’t have any major negative impacts AND will actually provide some benefits (listed above)

Caffeine and Sleep

As we mentioned in the “Mechanisms of Caffeine” section above, caffeine blocks adenosine and as a result can make sleep difficult. The obvious fix for this is not to drink caffeine too late in the day. If the average biological half-life for caffeine is 5 hours and you want to go to bed at 10.30pm, then no caffeine after 5.30pm. You can adjust this yourself depending on how you feel you react to caffeine, though it’s generally better to err on the side of caution. Feeling like you can easily get a good night’s sleep after a cup of coffee and actually having a good night’s sleep are very different things. It’s better to gauge it over the course of a week by taking coffee as late as you think is doable, ensuring you get your 7-8 hours in bed, and seeing how you feel at the end of the week. Adjust accordingly (though, yes, there may be mitigating factors and caffeine might not be to blame for all your sleep woes).

On a side note, an interesting point worth noting (we will cover in more detail in our article on sleep) is that adenosine is a Ghrelin agonist. Now if you have read our other articles on diet and on obesity, you’ll know Ghrelin is responsible for your short term hunger signals. This means, that an increase in adenosine (due to its place being unceremoniously stolen by caffeine) can increase hunger signals and lead to snacking! If you feel tired, get some rest! (…or have a cup coffee and eat a bar of chocolate!)


Withdrawals & Caffeine Chelators

Caffeine withdrawals are pretty common and occur due to the fact that caffeine is addictive (who’d have thunk it). Generally speaking, caffeine withdrawals should only last a few days (potentially up to a week if you’re a slow metaboliser) and will leave you a little cranky and probably the proud owner of a headache. There are no serious side-effects of caffeine withdrawals, and the headaches are usually the worst of it. Some people advocate the use of things like Rutacarpine to help remove caffeine from the system, though this is usually a sneaky trick to get the best of both worlds. Things like Rutacarpine are said to chelate caffeine (bind to it and therefore reduce the time it takes to remove it from the system), though this begs the question: are products like Rutacarpine just reducing the effectiveness of caffeine (as opposed to allowing have the benefits of caffeine with none of the drawbacks). Also, the bigger questions of whether or not things like Rutacarpine actually work have yet to be comprehensively studied. We will update this when we have dug a little deeper!


Caffeine Substitutes

For those who want to go a more natural route and minimize the amount of caffeine they consume, a number of things should be noted:

•  Caffeine can be very beneficial

•  Stimulants are hard to replicate naturally (except with other stimulants)

•  Caffeine is usually consumed as part of a beverage (e.g. tea) which is both delicious and provides additional antioxidants and other nutrients

Ok, so if you still hell bent on removing all forms of caffeine from your diet (at least for the short term), here are a few things that can help.

1. Tyrosine and… have been shown to help with focus and cognitive function, so adding these to a drink or morning juice may help give you a little extra pep.

2. B vitamins are hugely important in both metabolism and energy production/regulation, so taking a good multivitamin or B-complex will help.

3. Have suitable hot drink replacements (herbal teas etc.) to replace your usual morning drink as it will make removing caffeinated drinks from your day infinitely less painful.

4. Exercise more and sleep more. Yes, they’re not the recommendations you want but regular exercise and quality sleep will both improve energy levels!


As we continue tumbling down the rabbit hole that is our 521 journey towards better understanding our heath, it’s safe to say caffeine and adenosine are important to help further a basic understanding of how complex and highly regulated our bodies are: Caffeine illustrating that the poison is in the dose, in that it can be both healthy and damaging; Adenosine showing us just one of thousands of synergistic mechanisms in place to help keep you alive and well.

Unless you have serious adrenal issues or are under 18, then the health benefits of caffeine will far outweigh the possible negatives. But, as should be evident from the article, moderation is key.  

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