Or, at least it was.
It goes back, perhaps, hundreds of years. And it wasn't outlawed until the late 1990s.
Who in the name of Vlad the Impaler would put blood in beer?
Well, Dow Chemical for one. Fifty years ago, it won a U.S. patent for a technique to infuse beer with blood.
For those opposed to cannibalism, don't panic. It was not human blood. It was cow blood.
And to be completely clear, they weren't actually sacrificing calves over the mash tun - although, come to think of it, that might explain the gamy flavor of Zima.
Instead, the bloodletting involved the use of albumin, which is the protein in plasma.
They weren't adding it for flavor. Instead, like many beer ingredients, it was intended to make your beer look better.
This precious bodily fluid is perfect for removing what beer experts call "chill haze," the cloudiness that appears in light-colored beer when it's poured into a glass at a cold temperature.
The haze is created by microscopic proteins that are not removed through normal filtering. The haze has no flavor, and you wouldn't notice it if you drank straight from the bottle. But appearance is important, so brewers are forever in search of procedures and ingredients to keep their beer clear and bright.
Many favor Irish moss, which is red algae that is often used as a thickener in ice cream. When it's added to beer during boiling, it tends to attract those unsightly proteins in clumps, which are more easily filtered. (Next time you visit a brewery, look around for bottles of Whirlfloc; that's the brand name for concentrated Irish moss mixed with purified seaweed.)
Irish moss is just one of many recognized clarifiers, or finings. Over the years, brewers in search of clear beer have turned to clay, diatomaceous earth, charcoal, gelatin, papaya proteins and fish guts.
Wait a sec, fish guts?
Well, technically, the ingredient is called isinglass, but basically it's collagen from fish bladders. Added to beer during fermentation, it turns tiny floating yeast cells into flakes, which then sink to the bottom of the tank to be easily separated from your beer.
OK, I know this is a lot of tech talk, and you're out for blood.
We can blame this grisly practice on winemakers, who learned long ago that harsh tannins and other impurities can be removed by adding egg whites to casks. No yolk!
It's the egg-white protein known as albumin that does the trick. It's the same protein found, in higher concentration, in animal blood. According to various historical accounts, ancient winemakers discovered that dried ox blood helped clarify their wine.
Although it's uncertain whether commercial breweries ever dabbled in blood, in 1963 a trio of inventors at Dow Chemical suggested just that. In a patent titled "Clarification of beverages with animal blood albumin," they described a process of eliminating dastardly chill haze with a 1 percent solution of bovine blood.
The treatment, they declared, would "yield a clear beer."
And good news, other scientists suggested, it's the perfect alternative for those with fish allergies.
Now, much as one might enjoy a nice, frothy mug of Blood Beer this Valentine's Day, don't bother looking for it.
In the late 1990s, when the world was freaking over the mad-cow disease, government regulators banned the use of blood albumin in food products.
Presumably, however, daring homebrewers can skirt the law.
So, grab your syringe and don't forget: Blood Beer is best enjoyed at a proper serving temperature of 98.6 degrees.
"Joe Sixpack" is written by Don Russell. For more on the beer scene, sign up for his weekly email update at joesixpack.net. Email: firstname.lastname@example.org.