Drinking animal blood is not inherently toxic, and humans have consumed it in various forms for thousands of years, but doing so carries real risks that depend heavily on whether the blood is raw or cooked, which animal it comes from, how much you drink, and how the animal was raised. Cooked blood products like blood sausage, blood pudding, and blood-thickened soups have long track records in cuisines around the world. Raw blood, on the other hand, opens the door to infections, parasites, and prion diseases that cooking would otherwise neutralize. The safety picture is genuinely complicated, and the details matter more than a blanket yes or no.
Blood as Food Has Deep Roots
Blood has been used as a high-protein ingredient in human food and animal feed across many cultures, with documented economic, environmental, and nutritional benefits.1PubMed. Issues related to the use of blood in food and animal feed The Maasai of East Africa mix cattle blood with milk. Scandinavian traditions include blood pancakes and blood pudding. Filipino dinuguan is a savory stew thickened with pork blood. British black pudding, Spanish morcilla, Korean sundae, and Taiwanese pig blood cake all use cooked blood as a primary ingredient. These are not curiosities or relics. They are mainstream foods in their respective cultures, sold in supermarkets and served in restaurants.
The fact that so many culinary traditions independently arrived at blood-based foods tells you something important: blood is a dense, protein-rich ingredient that, when handled and cooked properly, can be eaten without obvious harm. The problems arise at the margins, and those margins are worth understanding.
What Is Actually in Blood
Animal blood is mostly water and protein. The dominant protein is hemoglobin, which carries oxygen and is packed with heme iron, the form of iron your body absorbs most efficiently. A comparative study of porcine, chicken, and duck blood found that porcine blood had the highest protein and fat content, followed by duck and then chicken, while chicken blood had notably higher carbohydrate content.2PubMed Central. Comparative Study on Compositions and Functional Properties of Porcine, Chicken and Duck Blood Blood also contains albumin, globulins, and smaller amounts of minerals and vitamins.
The high heme-iron content is the most nutritionally significant feature, and it cuts both ways. For people who are iron-deficient, blood-based foods can be a potent and affordable source of dietary iron. For people who are not deficient, that same iron load becomes a potential hazard, which we will get into shortly.
The Iron Overload Problem
Heme iron from animal sources is absorbed at a much higher rate than the non-heme iron found in plants. Your body has no efficient mechanism for excreting excess iron once it has been absorbed, so over time, chronic overconsumption of high-iron foods can lead to a buildup that damages the liver, heart, and pancreas. This is why people with hereditary hemochromatosis, a genetic condition that causes excessive iron absorption, are specifically advised to avoid blood-containing foods, offal, and red meat from mammals.3PubMed Central. Managing Genetic Hemochromatosis: An Overview of Dietary Measures, Which May Reduce Intestinal Iron Absorption in Persons With Iron Overload
Even for people without hemochromatosis, drinking blood in large quantities would deliver a concentrated iron dose that could cause nausea, vomiting, and gastrointestinal distress in the short term. The occasional bowl of blood soup or slice of blood sausage is a different situation from drinking cups of fresh blood. Dose matters enormously here. The traditional culinary uses of blood tend to incorporate it as one ingredient among many, diluting the iron load with starches, fat, and other components. Drinking it straight and in volume is a different proposition.
Infectious Risks of Raw Blood
The biggest safety divide is between raw and cooked blood. Cooking kills bacteria, viruses, and parasites. Raw blood, especially from animals that have not been veterinary-inspected, can carry a wide range of pathogens.
A systematic review of health risks associated with Africa’s bushmeat trade identified 66 microbes and parasites in wild animal products that are known human pathogens, including 23 viruses, 19 bacteria, and 24 parasites, with an additional 21 organisms classified as opportunistic or uncertain human pathogens.4PLoS Neglected Tropical Diseases. Systematic review of health risk assessment in Africa’s bushmeat trade: Are there any risks assessed? While that review covers all animal tissues and not blood exclusively, blood is one of the primary routes through which bloodborne pathogens move between species. Raw blood from cattle, goats, and pigs can harbor bacteria like Brucella, Salmonella, and pathogenic E. coli, along with parasites like Toxoplasma and Trypanosoma species depending on the region.
The risk is not theoretical. Communities that traditionally drink raw animal blood do experience higher rates of certain zoonotic infections. This does not mean every sip of raw blood will make you sick, but the probability of encountering a pathogen is meaningfully higher than with cooked blood products, and the consequences of some of these infections, particularly brucellosis or certain parasitic diseases, can be severe.
Prion Diseases Are the Scariest Outlier
Prions are misfolded proteins that cause fatal, incurable brain diseases in both animals and humans. The most well-known example is bovine spongiform encephalopathy (BSE, or “mad cow disease”) in cattle, which can cross into humans as variant Creutzfeldt-Jakob disease (vCJD). Prion diseases remain a concern in blood products because prions are extraordinarily resistant to heat, chemical disinfection, and standard sterilization methods. Cooking blood to safe temperatures for bacteria will not reliably destroy prions.
Research has confirmed that prions can be transmitted through blood. In transfusion experiments with sheep, animals that received whole blood, buffy coat, or red blood cells from infected donors all developed clinical signs of prion disease.5PLOS ONE. Impact of Leucocyte Depletion and Prion Reduction Filters on TSE Blood Borne Transmission Even when specialized filters were used to remove white blood cells and reduce prion load, some recipient animals still showed abnormal prion protein accumulation in their tissues, though clinical disease was prevented in those cases. Outbreaks of vCJD linked to blood transfusion and organ transplantation have also been documented in humans.6PubMed Central. Prion diseases as transmissible zoonotic diseases
The practical risk of contracting a prion disease from drinking animal blood in countries with effective BSE surveillance is very low. Regulatory systems in the US, EU, and other regions test cattle and remove animals at risk from the food supply. But the risk is not zero, and it is one that cooking cannot mitigate. This is one of the strongest arguments against drinking raw blood from ruminant animals, particularly cattle, in any context.
Why Cooking Makes Such a Difference
Blood is an ideal growth medium for bacteria. It is warm, wet, protein-rich, and has a near-neutral pH. Once an animal is slaughtered, its blood begins to support microbial growth rapidly if not processed. Research on meat from animals with poor bleeding efficiency, where more residual blood remains in the tissue, shows significantly higher bacterial counts during refrigerated storage compared to well-bled carcasses.7PubMed Central. Bleeding Efficiency and Meat Oxidative Stability and Microbiological Quality of New Zealand White Rabbits Subjected to Halal Slaughter without Stunning and Gas Stun-killing Blood that sits at ambient temperature for even a short time becomes a bacterial playground.
Traditional blood sausages solve this problem through thorough cooking. A study of morcela de arroz, a Portuguese blood sausage, found that its traditional thermal process exceeded the conservative safe harbor of 90°C for 10 minutes, and testing detected neither Bacillus cereus nor Clostridium perfringens in any samples.8Journal of Food Processing and Preservation. Application of Unsteady‐State Heat Transfer Equations to Thermal Process of Morcela de arroz from Monchique Region, a Portuguese Traditional Blood Sausage The combination of heat and time reliably kills the vegetative bacteria and many of the spore-forming organisms that might be present. This is why cooked blood products have been eaten safely for centuries while raw blood consumption carries persistent risks.
If you are going to consume animal blood, cooking it to at least 70-75°C (about 160°F) internal temperature is the single most effective safety measure you can take, aside from prion risk, which heat does not address.
Heavy Metals and Environmental Contaminants
An underappreciated risk of drinking animal blood, whether raw or cooked, is the potential for heavy metal contamination. Animals accumulate environmental pollutants in their blood over their lifetimes, and blood can carry measurable concentrations of lead, cadmium, mercury, copper, and zinc. A study measuring heavy metals in sheep blood found that concentrations varied significantly by season. Lead, copper, and mercury were higher in spring when animals were grazing outdoors, likely reflecting greater exposure to contaminated soil and vegetation compared to winter when the animals ate stored fodder.9PubMed. Seasonal variations in the blood concentration of selected heavy metals in sheep and their effects on the biochemical and hematological parameters
This means the safety of drinking animal blood depends partly on where and how the animal was raised. Animals grazing near industrial sites, highways, or in regions with naturally high soil contamination may carry heavier metal loads. Cooking does not remove heavy metals. The contaminants are dissolved in the blood itself and will remain in whatever dish you prepare. For occasional consumption this is unlikely to be a health concern, but regular, high-volume blood consumption from animals in polluted environments could contribute to chronic heavy metal exposure over time.
Allergic Reactions to Blood Proteins
Some people can have genuine allergic reactions to proteins in animal blood. Serum albumin, a major blood protein, is a recognized allergen that causes IgE-mediated reactions. Roughly 20 to 30 percent of people allergic to cats or dogs show IgE reactivity to animal albumin, and because albumins are structurally similar across mammalian species, these allergies frequently cross-react.10PubMed Central. Albumins represent highly cross-reactive animal allergens A person with a pet dander allergy could plausibly react to bovine or porcine blood albumin.
Meat allergies driven by serum albumin sensitivity have been documented as well. In a study of children sensitive to beef, significant cross-reactivity was observed between bovine and ovine serum albumin, and some children developed immediate allergic reactions including severe respiratory symptoms when challenged with albumin.11PubMed. Meat allergy: I–Specific IgE to BSA and OSA in atopic, beef sensitive children Blood, being especially rich in albumin compared to cooked muscle tissue, could potentially trigger stronger reactions in sensitized individuals. If you have a known allergy to a specific animal’s meat or dander, you should be cautious about consuming that animal’s blood.
What Vampire Bats Tell Us About a Blood-Only Diet
If blood were a well-rounded food, you might expect nature to have produced more blood-feeding mammals. It did not. Vampire bats are the only mammals that feed exclusively on blood, and they manage it only because of extensive genetic adaptations that most other mammals lack. Genomic analysis of the common vampire bat revealed gene losses tied to reduced insulin secretion, limited glycogen storage, a unique stomach physiology, and enhanced iron excretion.12PubMed Central. Gene losses in the common vampire bat illuminate molecular adaptations to blood feeding That last point is especially telling: vampire bats have lost a gene called REP15, which appears to help them excrete excess dietary iron, something humans cannot do efficiently.
Blood is extremely low in carbohydrates and fat while being overloaded with protein and iron. For a human, subsisting on blood would mean severe caloric insufficiency, dangerous iron accumulation, and inadequate intake of essential fatty acids, fiber, and many vitamins. Even cultures that drink blood regularly treat it as a supplement or ingredient, not a staple food. The vampire bat’s extreme genetic specialization is a reminder that blood is nutritionally lopsided in ways that require biological workarounds no human possesses.
Handling and Storage If You Choose to Use Blood
If you are working with animal blood in a culinary context, handling matters. Blood coagulates quickly once collected, so anticoagulants are typically added to keep it liquid for cooking. Sodium citrate is an effective and food-safe anticoagulant commonly used for this purpose. If blood needs to be stored for more than a few hours, acid citrate dextrose is preferred. Blood should not be stored for more than about two weeks even under refrigeration.13PubMed. Use of blood and blood products Freshness matters because, as noted earlier, blood supports rapid microbial growth.
For home cooks interested in traditional blood dishes, the safest approach is to source blood from a reputable butcher or slaughterhouse where animals have been veterinary-inspected, keep it refrigerated from the moment of collection, use it within a day or two, and cook it thoroughly. Many traditional recipes call for simmering or boiling blood-based mixtures for extended periods, which achieves more than adequate pathogen reduction. The long cooking traditions around blood sausage and blood soup exist partly because people learned through experience that well-cooked blood kept better and caused fewer problems.
When Blood Drinking Becomes a Clinical Concern
Separate from the food-safety question, there are rare psychiatric cases where people develop compulsive urges to consume blood. One case report describes a proposed condition called hemomania, characterized by uncontrollable urges to see, release, or ingest blood. The patient collected blood in vials, sometimes mixed it with water and drank it, and also consumed blood from other people and animals.14PubMed Central. Case Report of Hemomania: Recurrent Bloodletting and Blood Consumption From Self and Others This behavior overlapped with non-suicidal self-injury, impulse control disorders, and elements of what has historically been called clinical vampirism. It is not a formally recognized diagnosis, but clinicians have documented enough cases to propose a framework for understanding it.
This is a fundamentally different situation from choosing to eat blood sausage or following a cultural tradition. If you or someone you know experiences persistent urges to consume blood outside of normal culinary contexts, that warrants a conversation with a mental health professional. The physical risks in these cases are compounded by the psychological dimensions, since the blood consumed is often raw, unscreened, and sometimes human in origin.
Animal Welfare in Blood Collection
For readers concerned about the ethics of blood as a food product, the sourcing matters. In conventional slaughter, blood is a byproduct that is collected as part of the process, and using it for food is arguably less wasteful than discarding it. Some traditions, however, involve collecting blood from living animals, such as the Maasai practice of drawing blood from cattle via a small jugular puncture. Animal welfare guidelines suggest that no more than about 15 percent of an animal’s estimated circulating blood volume should be removed in any four-week period, with a ceiling of 25 percent only under special oversight.15Animal Welfare. Welfare of animals kept for harvesting of blood Exceeding these limits risks anemia, shock, and death in the animal. When blood is collected at slaughter, this constraint does not apply since the animal is being processed for meat regardless, and the blood would otherwise be discarded or rendered into low-value products like fertilizer.