Acetaldehyde, the part of a night out nobody mentions

Ask ten people at a bar what makes the next morning rough and you'll hear "dehydration" nine times. The tenth person is usually a nurse, and she'll say a word most of us have never heard: acetaldehyde.

Here's the short version. Your liver doesn't get rid of alcohol in one step. An enzyme called alcohol dehydrogenase turns ethanol into acetaldehyde first, and a second enzyme, ALDH2, turns acetaldehyde into acetate, which is basically vinegar and harmless. The middle step is the problem. Acetaldehyde is reactive and toxic, and for as long as it hangs around, your body is cleaning up after it.

Why some people turn red after one drink

If you've ever had a friend go bright red halfway through their first beer, you've watched this happen in real time. A common variant of the ALDH2 gene makes that second enzyme slow. Acetaldehyde builds up, blood vessels widen, and the face flushes. A 2009 paper in PLoS Medicine by Philip Brooks and colleagues put the number of people carrying it at roughly 540 million worldwide, most of them of East Asian descent. It's not a tolerance thing, and you can't train it away.

Most people don't flush, but everyone makes acetaldehyde. The difference is how fast you clear it.

Where glutathione comes in

Glutathione is one of the molecules your body uses to deal with reactive compounds like this one. It's a small protein your cells make from three amino acids, and the liver keeps a big supply of it. A long night of drinking uses that supply up faster than usual.

That's the reason Glug is built around 500 mg of glutathione, plus NAC, which your body uses to make more of its own. We're not going to tell you a drink mix rewrites your liver chemistry. What it does is put the raw material back at the point where your body is spending it.

The timing part

When you finish your last drink, most of the night's alcohol usually hasn't been processed yet. Your liver works through roughly half a standard drink an hour, so a few drinks over an evening keeps it busy well past the time you fall asleep. Which means the acetaldehyde shift happens overnight, mostly while you're unconscious.

So that's when we'd rather the glutathione show up. Not at 8 p.m., hours before it's needed. At 1 a.m., on the nightstand, in a glass of cold water.

The nurse at the bar, by the way, was drinking club soda. She had a 7 a.m. shift.