Blame it on the a-a-a-a-a-alcohol

This is the most requested post I’ve written yet; but it is dedicated to the first person to ask me for it, and the person who has been waiting the longest for their request post to be written, my lovely fiancé. Sorry for the wait, G!   

 So, hangovers. That moment when you wake up, feeling like a small furry animal died in your mouth, with an army of industrious builder ants hammering wildly in your brain and the sensations that someone appears to have replaced your bowels with a churning cement mixer of doom. Or, in technical terms, you wake up thirsty, with a headache, nauseous and quite probably suffering from diarrhoea. Chances are good you’re also feeling somewhat depressed and negative (not surprising, really, under the circumstances). 

The actual causes of all the hangover symptoms are not entirely understood; what I’m going to explain is the best explanation we have, at the moment. It could be wrong though, science is like that sometimes. One thing is certain though, when you’re hungover, your body is dehydrated. Ethanol (the alcohol in alcoholic drinks) causes increased production of urine. This accounts for the well-known fact that pints go straight through you, and results in your body being dehydrated. Dehydration in turn leads to a very dry mouth (hello small furry animal), a headache (oh, and welcome small hammering ants), and a sense of lethargy (can I be bothered to get out of bed? No…) 
Ethanol causes dehydration by inhibiting a hormone, vasopressin. Vasopressin’s job is to regulate water retention; when the body is dehydrated, vasopressin is produced. It heads straight to the kidneys, where it prevents water from escaping the body by altering the permeability of cells in your kidney tubules. It makes certain cells more permeable, so that they will reabsorb more water and leave less in your urine. Ethanol, however, inhibits vasopressin. So your kidneys don’t get the messages telling them to ‘hang onto some of that water please’, and instead they merrily get rid of it all, leaving you dashing to the loo every half-pint and with a raging headache the next morning.  
A possible cause of other hangover symptoms has to do with the way your body breaks down alcohol. In your liver, ethanol is broken down by a stunning little enzyme called alcohol dehydrogenase. You may never have heard of it, but if you like a drink or ten, then you should probably list it as among your favourite enzymes.  What alcohol dehydrogenase does is convert ethanol into acetaldehyde, which is then converted into acetic acid by another enzyme. 
These reactions, however, cannot take place on their own. They need a little help from a co-enzyme. If enzymes were superheroes, co-enzymes would be their side-kicks. They work with enzymes to help them do their stuff. In the case of alcohol dehydrogenase, the co-enzyme NAD+ accepts spare electrons from the reaction and uses them to become NADH. The problem is that there are many other reactions in your body that use NAD+, including the citric acid cycle, which is a crucial step in respiration. With an excess of NADH and insufficient NAD+, the citric acid cycle can’t function. Pyruvate, which is the starting product of the cycle, builds up. Tense music starts to play in your cells so you know things are getting bad. In order to stop you dying, your body uses lactate dehydrogenase to convert pyruvate to lactate, generating NAD+ again. Phew, you’re still alive. Good. 
But, your body has now used pyruvate that would usually be used to produce new glucose in your liver cells. That means that if your blood sugar levels drop, your liver will be less able to help bump them back up again. The theory is that this causes a lowering of glucose levels in your brain, which causes or contributes to fatigue, mood alteration and a lack of ability to concentrate. Meaning that if you were hungover right now, you probably wouldn’t have read this far. 
There are a few other theories and reasons why hangovers suck… firstly acetaldehyde, the middle product of the breakdown of ethanol, is quite toxic, certainly considerably more toxic than ethanol was in the first place. And not only is it produced whilst ethanol is being metabolised, it may also be present in your drink in the first place as a by-product of fermentation. Other by-products, including acetone, may also be hanging around. This is the reason why a distilled alcohol, like vodka, is reputed to cause less severe hangovers than darker alcohols; the distillation process removes some or all of the by-products. Unfortunately it can’t stop ethanol dehydrating you, or needing to be broken down into acetaldehyde and acetic acid.  So while it may make the hangover slightly less awful, it certainly won’t protect against it. 
Finally, the question that everyone really wants answered… how do you make it go away?? Well there is no proven remedy, despite the myriad of weird and wonderful ‘cures’ out there. Unfortunately, based on this model of what causes a hangover, there are really two simple things you need to make you slowly feel better… water and glucose. Or not drinking in the first place. Sorry about that.


4 thoughts on “Blame it on the a-a-a-a-a-alcohol

  1. Thank you! Fab post. Am tweeting/blogging/facebooking it 😀 ps. Drank wine again last night and feel like shite again. Can you work out and explain why spirits not only don't make me hungover, but also don't even make me drunk in the first place?

  2. Thanks Clare 🙂 I'll do some research for you. Off the top of my head, I would guess it's at least partially also to do with the byproducts of fermentation. And it's also partly genetic, personally I can practically get a drunk from a liquor chocolate!

  3. Pingback: Your Body: The Liver & Alcohol | The Molecular Circus

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