Sloppy Science: Why does alcohol get you drunk?

Few substances have as long and strange a history with the human race as the collection of liquids we call alcohol. For about as long as humans have been living together in large groups we have been consuming, fighting over, and occasionally procreating as a result of what is basically a low-grade poison.

The alcohol that we know and love (found in beer, wine, hard liquor, etc.) is called ethanol and it may disturb you to know that it is actually the waste produced by unicellular fungi called yeast. Yeast loves to eat/react with sugar, and when that happens ethanol and carbon dioxide are expelled. Humans make use of both of these products. When you bake a loaf of bread it is the carbon dioxide bubbles that make it rise as the alcohol is evaporated away. In beer, the same carbon dioxide produces fizzing as the alcohol primes you for karaoke.

The amazingly simple chemistry and minimal ingredients involved are the reason why many researchers believe humans were drinking wine 3,000 years before we invented pottery or the wheel. Yeast thrives on the skin of fruit and when that fruit starts to decay the yeast gains access to the sweet sugars within. Half-rotten fruit (especially grapes) is basically booze waiting to happen. It wouldn’t have taken much for Neolithic people to put two and two together and start serving fermented grape juice (AKA wine) with their mammoth steaks at dinner parties.

But why do we love alcohol so much? To answer that question you need to understand what happens when ethanol gets into your body: When you drink alcohol it makes its way through your stomach into your small intestine, where nutrients are absorbed by the blood. Ethanol isn’t much of a nutrient but it can still hitch a ride on your blood cells to any tissue in your body that contains water (they all contain water). Your brain in particular is a veritable paradise for the stuff. Alcohol is processed by the liver and kidneys and broken down/removed from the body at a rate of about an ounce per hour, it is also a diuretic, meaning it makes you pee a lot, but when you drink more than your body can process ethanol starts to build up in your tissues. That’s where the fun begins.

In your brain, ethanol slows things down. That is why we call it a depressant. Your brain contains different neurotransmitters, some activate parts of your brain (excitatory neurotransmitters) and others de-activate parts of your brain (inhibitory neurotransmitters). Alcohol stimulates the release of GABA (gamma aminobutyric acid) which is inhibitory and it prevents the release of glutamate which is excitatory. The influx of GABA turns down the parts of your brain that control inhibition, making you say and do things you would otherwise consider a bad idea. At the same time the parts of your brain that control reaction times, balance and coordination also get dialed down, making you clumsy and a bad driver. Too much alcohol can even turn off the parts of your brain that remind you to breath or gag, an effect that has robbed the world of many a great musician. We call this “alcohol poisoning.”

But beyond all of this flipping of dimmer switches, alcohol results in a flood of the neurotransmitter dopamine in your brain’s reward centres. The same thing happens when you win a hand of blackjack or steal a kiss from someone you like. It is addictive. That is what makes alcohol dangerous.

In the short-term, processing alcohol is a drain on your body’s water resources. As your body tries to flush your system through constant peeing and your liver uses even more water to break down ethanol, other parts of your body get dried up, including your brain. That is why you often feel so rough the next day. You brain has literally shriveled up and the tissues throughout your body cannot work how they are supposed to. Other important chemical balances like the level of potassium in your blood also get out of whack. Over the long-term, your liver is damaged by repeated exposure to the waste products released as ethanol is broken down. Your liver is a pretty important organ if you like being alive.

There is some evidence that a single beer or glass of wine per day may have long-term health benefits for some people, but that just speaks to what the role of alcohol should be in anyone’s life. As with most things that you end up craving, the name of the game is moderation.