What Happens To Your Body When You Drink Blood?
So you, like the terrifying Nosferatu, the quietly noble chupacabra, and Nicolas Cage before you, have heard the seductive call of the night and decided to give in to your insatiable lust for vita. Kudos. Time to nab an unsuspecting jogger and suck on their jugular vein with all the ferocity of an infant latching for the first time. You probably have a lot of questions. What will it feel like? What can you expect, besides serious jail time and the promise of being branded "that guy" at your high school reunion?
One of two things is about to happen, neonate. There is a chance that you will experience a rush of erotic power coursing through your undead frame, granting you clarity, strength, and power you never imagined possible. That's sort of a sucker bet, though. Odds are you'll just throw up a lot.
Red Dead Digestion
As LiveScience has pointed out, blood, which nine out of ten doctors agree is a great thing to have inside you, is actually pretty toxic when you put it anywhere besides your circulatory system. Drinking it, while decidedly cool in movies and video games, leads to a bad case of the tummy aches when you do it IRL.
There are plenty of reasons for this. Ignoring the pantheon of diseases you could pick up from lapping at your buddy's papercuts, blood tends to be pretty high in iron, a substance which is great for you in small amounts, but bad news when you overdo it. Haemochromatosis, or "too much iron" for the outside kids, can lead to significant liver damage, dehydration, nervous disorders and, ironically, low blood pressure.
But let's say that you refuse to be deterred. You wish only to sup upon the sweet nectar of mortals from this day forth. Alongside the sun, crosses, and Sarah Michelle Gellar, there's another time-honored vampiric vulnerability that you'll have to take into account: sodium intake. BBC's Science Focus states that the biggest danger to prospective blood suckers is the enormous amount of salt they'd need to take in if they wanted to hit their kcal needs for the day, roughly four and a half times the recommended daily allowance. If nothing else, that explains why the Children of the Night are kvetching about being so thirsty all the time.
Not that any of this is stopping anyone. The heart wants what it wants, and the BBC points out that communities around the world swear by snacking on people juice, saying that it benefits everything from libido to poop regularity. Doctors tend not to agree. What are you going to do? People buy Goop. People are weird.