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All the Gory Details: Dr. Tomas Ganz Discusses Blood Drinking

Dr. Tomas Ganz, Professor of Medicine and Pathology at University of California Los Angeles, at his home in March 2014. Picture: Tomas Ganz.

In 2015, Dr. Tomas Ganz was quoted in various articles for his views on blood drinking in regard to self-identified vampires. I reached out to him to discuss his views further, and our interview was published in Vamped the following year.

Recent interactions with people in our affiliated Facebook group, Vampire Community, have inspired me to formulate further questions—mainly concerning iron and blood consumption.

I emailed Tomas on May 28, 2016 and he replied the same day. To add context, this is the introduction I gave in my email:

Many of my questions below relate to iron as in the vampire community many sanguinarians discuss iron poisoning and how ingesting too much blood can make them sick. I am trying to build a basis for this and give people a better understanding of the topic and a point of reference for learning.

Here are the questions I emailed and his replies:

Erin Chapman: Can you explain for our readers your field of study and give us a bit of background on what you do?

Tomas Ganz: I am a Professor of Medicine and Pathology at UCLA, and a Principal Investigator at the UCLA Center for Iron Disorders. For the last 18 years, my research has focused on the mechanisms by which humans and animals regulate the amount and distribution of iron in their bodies, and on the diseases that cause iron dysregulation. My research group discovered that there is a hormone, called hepcidin, that regulates the amount and distribution of iron in the body. We also discovered a second hormone, erythroferrone, that regulates hepcidin in response to the iron requirements for the production of red blood cells. Finally, we described the regulation of hepcidin during infection, where iron in blood plasma is lowered to starve infecting microbes of iron.

EC: Can you explain how the body works concerning ferritin and iron levels? What are the optimal levels that a person should have and also what happens to the body when someone has either low levels or high levels? How much iron should a typical person ingest daily?

TG: Blood plasma (the pale yellow liquid in which blood cells float) receives iron from the diet, from places where iron is stored (mainly the liver) and from cells involved in recycling iron from used up red cells and other worn out cells. The iron in plasma is then distributed all around the body but most of it flows to the bone marrow to make new red blood cells to replace the ones that have worn out. The amount of iron in plasma is regulated by the body similarly to the levels of glucose (sugar) and other important substances for body metabolism. Plasma can be thought of as a railway station into which trains bring iron from various places and then take it out to other destinations. The total amount of iron in the bodies of normal adults is 3-5 grams but this is not easily measured. Ferritin is the protein that cells use to store extra iron. In healthy people, ferritin levels in blood are a good measure of total body iron. The normal levels of ferritin in serum (the liquid part of plasma after the clot and cells are removed) depend somewhat on the lab where the test is performed. At UCLA the normal range is 20 to 250 ng/mL for adult males, 10 to 120 ng/mL for adult females, 18 to 39 years,  and 12 to 263 ng/mL for females, 40 years and older. Per US Office of Dietary Supplements, the average daily iron intake from foods and supplements is 13.7–15.1 mg/day in children aged 2–11 years, 16.3 mg/day in children and teens aged 12–19 years, and 19.3–20.5 mg/day in men and 17.0–18.9 mg/day in women older than 19.  Of this, only about 10% is taken up by the body and the rest goes out of the body in stool. In healthy people, the amount of iron taken up from the diet goes down if they have already enough iron in the body, and goes up if they become iron deficient.

People with too much iron in the body (“iron overload”) usually have genetic conditions that cause them to take up too much iron even when their body stores are already normal or even high. Others have blood disorders that require blood transfusions which deliver large amounts of iron into the body without any regulation. When the amount of iron in the body is over about 10 grams, the regulatory systems will fail and allow too much iron to enter the blood stream, leading to deposition of surplus iron in the liver, the heart and other organs. Over many years, the large amounts of extra iron damage the tissues where the iron is deposited, leading to liver and heart disease. Another form of iron poisoning can develop over several hours, usually in children who swallow large amount of iron pills, mistaking them for candy.

People with low body iron (and therefore low serum ferritin) do not make enough red blood cells and become anemic (have too little hemoglobin in red cells). They also lose iron from important iron-containing enzymes in tissues, especially muscles. People with iron deficiency complain of being tired and having low energy. The main cause of iron deficiency in developed countries is blood loss from the body, usually from excessive menstrual blood loss in women or from slow bleeding in the stomach or the intestine in both genders. Worldwide, diets very low in iron cause iron deficiency but this takes many years to develop.

EC: I have seen some iron supplements such as Palafar that contain up to 300 mg of iron in one pill. How is it possible for the body to handle iron in such a high dosage? Does it absorb all of it?

TG: Palafer contains 300 mg of iron fumarate but only 100 mg of this is elemental iron, the rest is not iron. In healthy people, the body regulates the amount of iron taken up from the diet or from supplements, decreasing the amount of iron that enters the blood when the body already has enough iron. For this reason, iron overload is rare even in people who take iron supplements. However, some people may be genetically predisposed to absorb more iron, often without knowing it, and they may be harmed by excessive iron supplements.

EC: You elaborated before in our last interview on Vamped that the nutritional value of blood is as follows: “100 ml (3.3 oz) of blood contains 12-15 grams of hemoglobin (protein) that contains 40-50 mg of iron, 8 g of other proteins, 0.9 g of salt, 0.1- 0.2 g of sugar and 0.1- 1 g of fat, depending on when the last meal before the blood collection was consumed. If we do the basic math and use the data you supplied for the nutritional value of human blood, a sanguinarian could consume 600 ml (50g per ml) of blood a day to equal the same amount of iron that is included in one Palafar pill that is 300 mg? Would the absorption rate be the same as with a supplement and is this something that would be safe to do on a daily basis?

TG: In the intestine, humans take up iron in two major ways, either as ferrous iron (a form of iron with two positive electrical charges) or as heme iron (a form where iron is inside an organic chemical called porphyrin). However, ferrous iron is not common in nature because it easily reacts with oxygen to make ferric iron. So, elemental iron in the diet is mainly ferric iron (with three positive charges) which has to be converted by intestinal processing to ferrous before it can be taken up. Most iron pills are made with ferrous iron because it is more soluble and more efficiently taken up in the intestine. However, it is also more irritating to the lining of the intestine.

The equivalent of the 100 mg of ferrous iron in the Palafer pill would be 200 ml of blood or about a cupful. Surprisingly, we do not know much about how heme iron is taken up into the body, except that the process appears more efficient than other forms of dietary iron. That is why meat and liver are such good sources of iron, and blood would be too, except for its cathartic effects. So drinking a cupful of blood a day will not cause iron poisoning in most people but may cause diarrhea. The exception would be people who have the genetic disorder hereditary hemochromatosis (about 0.1% to 1% of the population in some parts of Europe, Australia and North America) for whom this amount of iron daily could cause iron accumulation over many years.

EC: What level of iron intake would a person have to ingest for iron poisoning? What would the symptoms be?

TG: What I am going to describe does not apply to persons drinking blood, unless they also have an underlying genetic disorder of iron metabolism. Their increased iron intake could then worsen or speed up the development of chronic problems. Chronic effects of excess iron are often quite subtle, and have been reported in patients who are genetically predisposed (hereditary hemochromatosis and similar diseases) or receive many blood transfusions for blood disorders. In the most severe cases, these patients develop heart failure and endocrine problems at a young age (in their 20s). Patients with milder disease get sick later in life and mainly suffer from liver problems (liver failure, liver cancer) and diabetes.

Acute iron poisoning in infants can develop after ingestion of more than 60 mg/kg of body weight of iron, i.e. a handful of iron pills containing 60-100 mg each. Adults have been reported to die after suicidal ingestion of more than 10 grams of iron. Such patients develop injuries of their intestinal lining leading to bleeding, low blood pressure, liver failure, coma and death. Again, this will not happen from drinking blood where the iron is much less concentrated than in pills.

EC: Many sanguinarians drink raw meat juice from packages that have steaks in them. We know this is considered myoglobin. Does this have the same nutritional value as blood? Can you elaborate on this if you know?

TG: The red meat juice probably contains both hemoglobin and myoglobin because meat contains not only muscle but also blood vessels and blood. For nutritional purposes myoglobin and hemoglobin are very similar molecules.

EC: I have spoken to sanguinarians that drink human blood versus animal blood. Is there a difference nutritionally between them and would one type be more ideal for them to ingest than another?

TG: Animal blood (cows, pigs) is less likely to transmit blood-borne diseases (hepatitis, HIV etc.) than human blood. Nutritionally they are identical.

EC: Could there be long term effects on a person’s digestive system if they are drinking human or animal blood daily? If a sanguinarian is drinking blood on a daily basis, can the body adapt to the amount they are ingesting and therefore need to increase their dosage eventually to get the same effective?

TG: I have no information about how human adapt to blood drinking over days or years. A few species of vampire bats drink blood as their sole source of nutrients and they are adapted to it over millions of years of evolution.

EC: Can you explain for our readers some of the basics concerning iron such as what is the difference between ferrous and ferric iron? What is the difference between the three types of ferrous iron: ferrous sulfate, ferrous fumarate and ferrous gluconate? Can you also explain the difference between heme and non-heme iron? With these categories where would human blood fall under?

TG: Ferrous iron contains two positive charges as is rare in nature because it gets converted to ferric iron (three positive charges) by reaction with oxygen.

Ferric iron is poorly soluble in water or in body fluids. Ferrous iron is more soluble, more chemically reactive, and more irritating to the intestinal lining.

Heme iron is the form of iron bound to an organic molecule called porphyrin, and it is made by animal cells and bacteria. It is the form of iron in hemoglobin and myoglobin as well as some iron-containing enzymes.

In the intestine, humans take up iron in two major ways, either as ferrous iron (a form of iron with two positive electrical charges) or as heme iron (a form where iron is inside an organic chemical called porphyrin). Ferrous iron is not common in nature or in natural diets because it easily reacts with oxygen to make ferric iron. So, elemental iron in the diet is mainly ferric iron (with three positive charges) which has to be converted by intestinal processing to ferrous before it can be taken up. Most iron pills are made with ferrous iron because it is more soluble and more efficiently taken up in the intestine. However, it is also more irritating to the lining of the intestine.

Blood contains about 40-50 mg of heme iron per 100 ml and about  50-150 micrograms of ferric iron per 100 ml, i.e. 0.05-0.15 mg per 100 ml of ferric iron. In other words, blood contains mainly heme iron.

EC: I’ve been told by my doctor that consuming folate, vitamin C and B12 help the body absorb the iron in a more optimal way. Can you confirm this and if so can you elaborate on this for me? Does this apply to ingesting iron supplements or would this apply to blood consumption as well?

TG: Of the three, only vitamin C helps iron uptake into the body (absorption), in part by helping to convert ferric iron to ferrous iron in the intestine. Folate and B12 are important for the development of red blood cells but not for iron absorption itself.

EC: In our last interview you said, “uncooked blood is a laxative probably because it is protein-rich and not easily digestible (cooking makes it more digestive as in the case with meat and other protein-rich foods.” If raw blood acts as a laxative, why do iron supplements make you constipated? I’ve also heard from sanguinarians that consuming blood as opposed to supplements doesn’t turn their stool black, can you elaborate on this?

TG: Blood drinking or digestion of blood from nosebleed or other internal bleeding does turn the stool black if enough is ingested. This black stool is called melena, and is a sign of internal bleeding into the stomach or upper intestine.

EC: If a sanguinarian cooked their blood as opposed to drinking it in raw form, do they lose nutrients like when we cook vegetables as opposed to ingesting them raw? Would cooked blood have the same laxative effect on the body?

TG: No, cooking makes the blood (and most food) more digestible, as in blood sausages. Cooking will also make it less laxative.

The laxative property of blood is not from iron but from the very large and poorly digestible liquid protein load that acts to draw in more water from its environment. This type of effect is called “osmotic diarrhea” and is similar to the effect caused by magnesium salts and indigestible sugars which are also not absorbable in the gut and draw in more water, causing the liquid in the lumen to increase in quantity.

Iron pills change the populations of different bacteria in the intestine by making iron more available and thereby selecting bacteria that thrive on more iron. Normally, about 30% of stool are bacteria so it matters which kind and how many there are. The change in bacteria can cause either constipation or diarrhea but mostly constipation. This is why iron is often (but not always) constipating.


  1. our interview was published in Vamped the following year: Erin Chapman, “Interview with Dr. Tomas Ganz, Regarding His Views on Sanguinarianism,” Vamped, February 17, 2016, accessed May 31, 2018,
  2. our affiliated Facebook group, Vampire Community:
  3. Here are the questions I emailed: The last question of the interview I reached out to Tomas after he sent his initial response, to ask him to elaborate. The second and third paragraph from that response are from his follow up that I was emailed on May 31, 2018.

For an example of  a self-identified vampire drinking animal blood as a human blood substitute, read “Got Blood? What Self-Identified Vampires Get from Raw Steaks.”

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Written by Erin Chapman

Erin is Vamped’s Co-administrator. She is the owner of Vampire Classifieds and Horror Classifieds. She has 2 turtles; has 15 piercings and 5 tattoos; loves turtles and walking around in bare feet. She has a degree in marketing and sales and has been in the industry for over 12 years. She lives in Vancouver, Canada.

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Monthly Digest #44–45: March/April 2018