Been wondering about this. I read somewhere that drinking mead while its fermenting was common practice in the old days.
However wouldnt it make you susceptible to developing a illness where your stomach begins to brew its own alcohol which causes you to be perpetually and mildly drunk?
It’s fine. It might be gross or sickly sweet, depending on how long it’s been fermenting.
Auto-brewery syndrome is super rare. It’s caused by conditions that allow brewing yeast (and other fermenting microbes) to live/thrive in your gut when they shouldn’t. Nutritional yeast is also living brewing yeast, though it’s dormant and not actively fermenting when eaten. You will get a bunch of B complex vitamins from the yeast!
But beware, my friends used to call green beer ‘fartzens,’ after the original Hefefartzen that we drank way too early.