24 Sep Why Does Alcohol Warm Your Throat and Chest? For Some of the Same Reasons it Messes With Your Brain
I’m a beer guy, but once in a while I indulge with some bourbon or whiskey. I’ve had a lot of vodka and gin in my life, but very little of those after one particular night at age 23. Walter, on the other hand, is a bourbon/whiskey connoisseur, everything from rotgut to Pappy van Winkle Family Reserve 20 yr. bourbon. We both have science/medicine backgrounds, but neither of us had every really considered why high alcohol drinks burn, or at least are warm, as you swallow them. I’m thinking that most people assume that high alcohol is caustic and basically burns the tissues as it is swallowed – but it turns out that there is much more to it than that.
Thermometers and Chili Peppers. Our story starts with two things most people can relate to – hot coffee and spicy food. Your body has evolutionary protection systems that alert you to eating/drinking things that could hurt you, including things that are “hot.” If you drink/eat drink something that is too hot, your body is going to let you know that this may not be good for you. Bitter is a second taste that is a warning for your body. Bitterness is harder for people to get used to because toxic plants/chemicals often taste bitter and your body has evolved to warn you to stay away from those.
Another thing that evolution has endowed humans with is efficiency. Very often, proteins will have more than one job, so that a smaller than expected genome can produce a larger than expected number of functions or will react to more than one stimulus. For the receptor that detects heat (called a nociceptor where noci = pain); heat this particular receptor protein knows; if it is triggered, something must be hot. But not everything that can trigger the receptor is hot in temperature. Another trigger for this same nociceptor is the capsaicin in chili peppers. Yet the reaction is the same, which is why we say spicy foods are “hot.” Your brain doesn’t know the difference between the two stimuli.
The protein involved in the response to heat and capsaicin is called TRPV1 (it stands for transient receptor potential cation channel subfamily V (vanilloid) member 1), but we can just call it the heat receptor from now on. However, there are several members of this same receptor family and they all react to something out of the ordinary. For example, TRPV3 (and other receptors) reacts to both cold temperature and menthol, which is why you think mint flavors or menthol are cold. Interestingly, cold stimulus makes your brain think that you are pulling in lots of crisp cold air, like when your nasal passages are wide open, and that’s why you think using menthol drops helps you breathe when you have a cold, but really your brains is just tricking you.
Anyway, back to our main receptor, the one for heat. Whether you consume something at high temperature or full of capsaicin, your brain reacts like each of them is very hot. Your body actually does several things, including trying to dissipate heat by sweating or breathing heavier, or craving cold water. What’s more, the degree of temperature or level of capsaicin can affect the number of receptors activated – the more receptors turned on, the hotter you think the stimulus is.
Alcohol sensation. Here’s where we get to our favorite pastime. Does any other chemical trigger heat receptors? Yes as you might expect, alcohol trips the same receptor – but not quite in the same way. Capsaicin interacts with the receptor directly, so it mimics a high temperature food or drink. Ethanol, on the other hand, makes the receptors more sensitive to heat. Instead of being activated at about 107˚F/41.6˚C, they turn on at about 93˚F/33.9˚C. Normal human body temperature is in the 98.6˚F/37˚C, so when you drink alcohol, it’s really your own body heat that activates the heat receptors.
Therefore, when you chug a ABV beer or take a shot, it warms or burns your throat. The phenomenon is concentration dependent, so the higher the alcohol ABV, the greater the number of heat receptors will be affected and the more you’ll feel it. That Russian Imperial stout gently warms your throat, while that shot of Everclear (is that even still around?) makes you burn.
So that explains why alcohol warms or burns your throat. But if you’re an avid drinker, you know that alcohol warms you in the chest too, not just your throat. So what’s up with that?
Ethanol boils at 173˚F/78.3˚C, significantly below the temperature of water (212˚F/100˚C). This means that when ethanol is in your mouth at 98.6˚F/37˚C, some molecules will be volatilized and turned into a gas. As such, they can be inhaled, and then they trigger heat receptors in your trachea and lungs. Therefore, with high proof alcohols you’ll likely feel the warmth not just in your throat, but in your chest (lungs) as well. You might even cough, since one of the triggers from having something “hot” in your lungs is for your body to cough it out.
At least one of your many cough reflex triggers is definitely mediated by this same heat receptor, and ethanol does exacerbate it. A research study done 12 years ago (and several others), showed that alcohol makes a cough worse, and it works through the heat receptor (linked here). The researchers induced a cough in guinea pigs with either a chemical that activates the heat receptor, or with saline which induces cough using a different mechanism. When these animals were given alcohol, the cough via TRPV1 got worse, but the saline-induced cough was unchanged. I believe this since a shot of pure alcohol will definitely make me hack for a while.
Alcohol/Heat/Behavior. Here’s where it gets really interesting. We’re all well aware that alcohol messes with your brain, specifically that it can act as a stimulant while drinking and as a depressant after blood alcohol levels get high or are decreasing. The actions of alcohol on the brain are immensely interesting – I think I’ll write about them very soon. But for today, let’s focus on the heat receptor overlap with alcohol. Research exists that shows alcohol can alter your behaviors via the heat receptor. It’s not surprising – many things mess with your brain. Can you believe that contracting certain STDs can actually make you more promiscuous! It’s how the microbe increases the chances it will be passed to a new host.
Here’s what scientists at the University of Texas found (linked here). Mice that lack the heat receptor (called a knockout mouse, where a specific gene has been removed or incapacitated) are more likely to choose to drink from a bottle containing an alcohol water solution than from a bottle with pure water. In addition, mice without the heat receptor had reduced ethanol-induced sedative effects and faster recovery from ethanol-induced motor incoordination. It seems that the heat receptor makes you want to drink more, and keeps you acting drunk longer.
Just how the heat receptor does this is a bit of a mystery, but several facts suggest that they work in the brain. One, these receptors aren’t just located in your respiratory and GI tracts (including mouth, throat, and lungs), they’re also present in your brain. Two, as we said above, the heat receptor is one of a group of channels/receptors known as nociceptors, where the noci- means pain. Three, nociceptor responses are involved in opiate and alcohol dependence in tangential ways (too much detail for this article). Therefore, it isn’t out of the realm of possibility that heat receptors contribute to your behavior when you’ve had too much and why you want to drink more after you start drinking.
This is where we see another crossover between spicy food and alcohol. Whether it’s alcohol or capsaicin that triggers the heat receptors, your body and brain react like you’ve been burned. Your brain reacts to pain by trying to make it hurt less by releasing endorphins, natural pain killers which make you feel good (high), and by releasing dopamine, which make you feel pleasure and rewarded. Whether it’s moderate alcohol or a spicy dish, many people feel sort of a runner’s high based on the heat receptor response (in addition to other pathways). So again, drinking a moderate amount of alcohol will likely make you want more.
There’s no getting around it, science rocks. But now you’re armed with alcohol/capsaicin knowledge. The next time you get pulled over and asked to take a sobriety test, tell them it’s not your fault, it’s that you have too many TRPV1 receptors and you just ate a spicy Thai dish. BTW – do I have to explain that our discussion today gives you ample reason NOT to chug an 11% beer to cool you off from that Phaal curry you just sucked down?
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