Animal blood — typically that of cow, pig, goat, lamb, chicken, duck and goose — has been used in traditional ethnic cooking across the globe and throughout time. In the spirit of "what's old is new again," along with a dose of culinary curiosity and Paleophilia, blood is making its way into the contemporary kitchens 
of professional chefs and home cooks alike.
Blood — thanks to the protein albumin, which coagulates with heat above 167 degrees Fahrenheit — is a traditional thickening agent in French cuisine, particularly in certain sauces and braises. It is also found in the savory Filipino stew dinuguan, which comes from the word dugo (meaning "blood") and may use pork, beef or chicken blood. In south India, lamb blood stir-fried with meat and spices (ratha poriyal) is a common dish, while blood soups can be found throughout the world: Polish czernina (made with duck blood), Swedish svartsoppa (goose blood), Vietnamese tiê´t canh (raw duck blood) and Korean haejangguk (ox blood), to name a few.
Blood sausages, which have been made for thousands of years by a number of cultures, refer to blood mixed with fillers and stuffed into casings. Arguably the most well-known blood sausage in the U.S. hails from the United Kingdom: black pudding (pig's blood and grain, usually oats). Other traditional blood sausages include Italy's biroldo (either pig's or cow's blood mixed with raisins and nuts), Ireland's drisheen (sheep's blood with cream, grains and spices), Spain's morcilla (pig's blood, rice and onions), Tibet's gyurma (yak blood with or without filler) and Estonia's Christmas verivorst (pig's blood, rye and flour served with lingonberry jam or sour cream, similar to Finland's mustamakkara).
Some cultures, namely in China, Vietnam and Thailand, serve the coagulated blood of chicken, duck, goose or cow that's been cut into blocks, known as "blood tofu." In addition, blood has roots in U.S. food history. According to The Oxford Companion to Food, 3rd ed. (Oxford University Press 2014), "the bleeding of horses was also common during the settlement of America." The horse blood was consumed either as a liquid or preserved with salt and cut into squares.
While little data are available on the nutrient content of blood (the USDA Nutrient Database has an entry for "blood sausage"), some sources promote blood consumption as a means to stave off anemia due to the high bioavailability of its heme iron. There also is little information about food safety considerations for cooking with blood. Livestock blood is considered a "meat byproduct" under the jurisdiction of the USDA Food Safety and Inspection Service. For pork blood to be certified "edible," FSIS requirements include that blood come from healthy animals (inspected before and after slaughter), be processed in an establishment under official control and be heat-treated. Pig blood also must come from a country free of classical swine fever.
According to the World Health Organization, in outbreak areas for H5N1 avian influenza virus ("avian flu"), reports of "a few human cases" potentially linked avian flu to the consumption of raw poultry, including raw blood-based dishes.
