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Caffeine and L-Theanine: The Good, The Bad, and The Myths
We all know that when you say “I need coffee,” you actually mean “I need caffeine,” and we just can’t seem to get enough of it! On the other hand, coffee and caffeine are associated with some negative effects: insomnia, hypertension, dehydration, etc. Since many people drink coffee, often even multiple times a day [1], we felt it was our civic duty as a nutritionally complete food company to investigate whether any of these negative effects associated with coffee and caffeine are actually true.
The Good, The Bad and The Myths
Most of us can probably relate: if we had to choose between coffee or cereal, the first thing we would consume in the morning would definitely be the beverage, not just because we love the taste, but because we need it. We can still feel the sleep in our eyes, our movements are sluggish, and we feel that between going back to bed or having a cup of coffee, the latter is probably better since it won’t get us fired.
But why do we feel we need it?
When digested, caffeine goes partly to the brain, where it fights against adenosine, the neurotransmitter responsible for making you feel sleepy [2].As you go through the day, adenosine is produced because you are doing physical work or because you are using your brain intensively. Adenosine then floats around until it finds a receptor it can bind to, causing your muscles to relax and making you feel sleepy [3, 4]. But caffeine stops this from happening. Caffeine has a similar chemical structure to adenosine, but it doesn’t bind to adenosine receptors, it just blocks them [5]. Imagine your dog jumping on your favorite chair and claiming it. It’s not made for him but he sits down anyway. Rude.
Normally, you wake up without adenosine molecules in your system. Getting a good night's sleep should metabolize them [6], but if you don't get enough (good) sleep, some of those molecules will remain. And then you wake up feeling groggy.
Caffeine may also be a cause of your morning grogginess: Because caffeine blocks adenosine, adenosine molecules build up. [7] By the time the caffeine wears off and adenosine can bind to its receptors again, this surplus of adenosine should be metabolized during sleep. But because there's so much of it (you just drank an espresso after dinner, right?), you're likely to wake up with a surplus of adenosine in your body, leaving you feeling groggy.
Anyway, based on these properties, you could say that caffeine is helpful: It’s known for being good at keeping you awake and alert, and rightly so. But it can also turn coffee drinking into a vicious cycle: You’re fighting grogginess with coffee, which leads to grogginess, which leads to drinking more coffee, which leads to… you get the picture. Still, caffeine is associated with other things, too. Read on to find out where some of these claims come from, and whether they’re true or false.
Caffeinated drinks dehydrate the body
Caffeine itself is dehydrating – it has a mild diuretic effect [8, 9]. This means that it promotes urine production, which means you lose more fluid. This diuretic effect is probably why the “coffee dehydrates you” myth still exists. To have a significant effect on your hydration status, you would need to consume at least 500 mg of caffeine a day – that’s about 5 cups of coffee [10-12]! It’s a fact that caffeine causes you to lose more water, but since you consume it as a beverage, you make up for it.
Bottom line: Coffee and other caffeinated beverages won't dehydrate you, especially if you drink them in moderation.
Coffee or caffeine causes constipation
The myth that caffeinated drinks cause dehydration could be the reason why they are also believed to cause constipation. Dehydration can cause constipation – if you lose too much water, there is not enough fluid left to properly process stool. But coffee does not cause dehydration! And if, in addition to coffee, you also drink some water throughout the day, you will more than make up for the slight diuretic effect of coffee. This way, there is no way you will become constipated from consuming some caffeinated drinks.
In fact, coffee might even have a mild laxative effect, not on its own, but in combination with stomach acid. A study in 1986 found that both caffeinated and decaffeinated coffee stimulate the production of gastrin [13]. Gastrin is a hormone that promotes digestion and speeds it up, making you have to poop [14]. Another study found that having a cup of coffee in the morning makes this process happen even faster – about twenty minutes after the subjects drank their coffee, they already needed to use the bathroom [15]. This doesn’t affect everyone, and the effects of caffeine differ from person to person. What we can conclude is that coffee does have an effect on your bowel movements, but it’s most likely promoting them rather than constipating you.
Caffeine causes insomnia
Remember adenosine? This claim probably stems from exactly what caffeine does – it keeps you awake by preventing adenosine from doing its job. But whether that leads to a diagnosis of insomnia remains the question. Caffeine can definitely cause sleep problems, especially when you consume it too late in the day, as it will increase the time it takes for you to fall asleep. On average, the time it takes for caffeine to wear off is around 6 hours, so drinking coffee a few hours before bed can mean having to count 5 million sheep before finally falling asleep [16]. According to some studies, caffeine can also decrease sleep quality if you consume too much of it (more than 400 mg a day) [17-19], but according to another study, caffeinated beverage consumption has no significant relationship with sleep quality [20].
When caffeine is consumed in low to moderate amounts during the morning hours, people who don't normally have trouble sleeping don't experience any sleep problems, and even people who do experience them don't generally feel that caffeine makes these problems worse [21]. Of course, this is obviously only the case if you don't generally possess a gene that might make you more susceptible to any of the effects that caffeine might have on a person.
So don't worry. If you monitor your own caffeine intake and keep it low, you should be able to get enough rest at night! If you want to keep accurate track of how much caffeine you consume, you should try our Plenny Shake Café ! Each shake contains 25 mg of caffeine per 100 ml of prepared product - that's about 100 mg of caffeine per 400 ml of shake or 400 kcal meal!
( 1 shake of 400 kcal = 300 ml of water + 96g of powder = 400ml of prepared product).
Caffeine causes hypertension.
Another commonly believed fact is that caffeine can cause hypertension. Let's analyze what this means exactly.
When you have hypertension, it means that your blood pressure is consistently elevated over a long period of time, compared to your “normal” reading. Every person has different blood pressure, and what is high for someone else may be normal for you. However, when your blood pressure is even higher on average for most of the day, you may be diagnosed with hypertension, often also called high blood pressure [22].
So why is caffeine thought to cause hypertension? Studies have shown that a cup of coffee with 140 mg of caffeine does raise blood pressure, but only for about 2 to 3 hours after consuming it [23]. It is not sure why it goes up, it has just been observed to go up. Because it only goes up for about 2 to 3 hours, you can argue that it does raise your blood pressure, but it does not necessarily mean that you have high blood pressure [24]. On top of that, it is also concluded that the elevations in blood pressure that occur after consuming caffeine are greater in people who do not consume caffeine regularly [25]. From these studies it can be concluded that caffeine does not cause hypertension , just temporarily elevated blood pressure.
However, if you have hypertension, it is recommended that you keep track of how much caffeine you consume. You can definitely have a cup of coffee every day, as it seems unlikely to have a significant effect on your blood pressure, but if you start increasing your caffeine dose, or suddenly start drinking caffeine when you usually never do, you could increase your blood pressure [26].
You know yourself better than anyone else, so use this information to know what applies to you. If you've always been drinking your morning coffee and you have high blood pressure, don't worry, you'll be fine. And if you don't have high blood pressure and you still drink coffee every day, you don't have to worry either, caffeine doesn't cause it, but if high blood pressure is hereditary, you may want to check your blood pressure regularly, as genetics play a big role [27].
Caffeine helps you lose weight
Is coffee really the magic drink that helps you lose weight? Various studies have pointed to different answers: some concluded that it plays a role, while others say that it cannot be determined whether coffee plays such a big role, or whether the weight loss was a result of drinking coffee and having a drink with healthy eating habits. Let's take a look at some of the findings.
First, keep in mind that the whole “coffee can help you lose weight” claim is about black coffee. A cup of coffee contains less than 5 calories per cup if you drink it black, but it can actually cause you to gain weight if you add a lot of sugar, milk, or cream, as it increases your calorie intake [28]. Pretty logical, right?
With that in mind, it might make sense that coffee could help you lose weight. Since a cup is low in calories, it's much better than drinking, say, a glass of Cola. Weight loss happens when you burn more calories than you take in, so if you consume fewer calories by replacing a high-calorie drink with a lower-calorie drink, like coffee, you may already be taking a step in the direction of weight loss (assuming you're taking other steps, too).
The caffeine found in coffee has also been found to boost metabolism [29, 30]. A faster metabolism means you'll burn more calories while you're "at rest," which means you'll burn more calories while doing... almost nothing! Hooray! However, this doesn't apply to everyone. As we said before, everything affects everyone differently - don't get your hopes up too high: coffee may not even be the miracle weight loss drink you think it is!
Another effect that caffeine has is that it might decrease feelings of hunger. A 2014 study found that daily coffee consumption caused participants’ feelings of hunger to decrease, as levels of ghrelin in the blood decreased [31]. Ghrelin is the hormone that makes you “feel” hungry – it’s also known as the hunger hormone for this reason [32]. On top of that, drinking coffee can also increase the satiety hormone called peptide YY, which is the hormone responsible for making you feel full [33, 34]. Obviously, this means that you’ll eat less.
On the other hand, other studies have concluded the opposite: some studies concluded that caffeine intake may promote weight loss, but the impact of the effect seems small, and it is also questionable whether it is clinically relevant [35]. Other studies found that caffeine might even make it harder to lose weight and instead cause you to gain weight.
The reason for this is that caffeine can lead to reduced sleep, which we mentioned earlier. Getting enough sleep is important in general, and if you want to know why, check out our article on why sleep is important . In this case, getting enough sleep is also important, as reduced sleep can lead to a decrease in leptin [36], the hormone responsible for decreased appetite, and an increase in ghrelin, the hunger hormone we talked about earlier, which can lead to increased appetite for high-calorie foods) [37]. This craving, if heard repeatedly, can lead to weight gain. Reduced sleep also means that you have more time during the day, which means more time to eat. If you are not good at controlling cravings in general, you may indulge more frequently, which is also a cause of weight gain. In short, drinking too much coffee or drinking it too late can be counterproductive if your goal is to lose weight.
It's safe to conclude that if weight loss is your goal, the solution is to be mindful of how much caffeine you consume and at what time. If you're looking for some tips on how to lose weight, check out our weight loss guide .
So... it's not bad?
Coffee, or caffeine itself, is definitely not bad for you; if you drink coffee or consume caffeine in moderation, you shouldn't experience any problems, if you're healthy and not allergic to any ingredients. The most important thing to keep in mind when consuming caffeine is what time you consume it and when you'd like to go to bed. Just drink it in moderation and don't drink it too late, and caffeine can give you that boost you might need in the morning. If you find that caffeine alone can't keep you focused, maybe you could even try a combination of caffeine and L-theanine.
W-what!?
L-Theanine! What, you've never heard of it!? Just kidding, we're not judging. We'll explain it here anyway.L-theanine is an amino acid found primarily in green tea. It is what gives green tea its unique flavor [38] and is thought to improve mental function as it has a similar chemical structure to glutamate [39]. Glutamate helps transmit nerve impulses in your brain (making it a neurotransmitter) and occurs naturally in your body. L-theanine behaves similarly to glutamates as it binds to the same glutamate receptors, but the effect is different. While glutamate has an excitatory effect (causing a neuron to fire an action potential), L-theanine has an inhibitory effect (preventing an action potential). Blocking the effects of glutamate stimulates the production of the neurotransmitter GABA, which has a stress-regulating quality and helps relieve anxiety [40]. In short, consuming L-theanine makes you relaxed without making you drowsy, as it lowers your blood pressure as you become less stressed.
L-theanine has also been found to produce more focus. During a study conducted in 2012, they looked at people who ingested either L-theanine or a placebo and found that the group that did not receive the placebo made fewer errors on a sustained attention task and improved focus [42]. In other studies, L-theanine combined with caffeine has been found to produce even better results when it comes to focus [43]. People who had a dose of both caffeine and L-theanine were found to be better at shifting attention and were faster and more accurate at doing so [44].
So, caffeine itself is already beneficial when the goal is to stay awake and feel less tired, and apparently, L-theanine in addition to caffeine seems to increase your concentration as well.
So, you're telling me... Drink all the coffee!?
No no no! Were you not paying attention? Don’t drink too much ! Caffeine definitely has its good qualities, but you definitely shouldn’t drink all the coffee you can find as it will be detrimental to your health. As long as you don’t overdo it and keep your caffeine intake under 400mg a day, you should be fine. So are we suggesting you mix your coffee with green tea? Of course, you’re free to experiment, but to make things easier, we developed Plenny Shake Chai Latte , which contains 30mg of caffeine and 25mg of L-Theanine per meal. And if you prefer a spill-proof bite rather than a drink, check out our Plenny Bar Hazelnut & Coffee , which has 90mg of caffeine and 225mg of L-Theanine per 400kcal bar. Both are great on the go, can double as both your morning coffee and breakfast, and will help you stay focused to boost your productivity. They are also packed with 26 vitamins and minerals, high in fiber, contain 20g of protein per serving, and so much more good stuff.So what are you going to eat? A plain old coffee or a deliciously nutritious Plenny meal?
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