Real-life vampire couple Pyretta Blaze and Andy Filth weren’t shy about explaining their unusual habit of drinking each other’s blood in spite of the practice’s ghoulish undertones. Although the sudden rise in vampire fan fiction has seemingly died down with the conclusion of two of its driving forces — Twilight and True Blood — it’s important to note that this obsession with vampirism is pretty unhealthy.

Drinking blood is often considered a defining characteristic of the vampire subculture; however, not all aspiring vamps agree on the source of their sustenance. While some settle for the blood of an animal, others insist that human blood is the only form of nourishment they require. Besides the obvious concern of blood borne illnesses, such as hepatitis B, hepatitis C, and HIV, consuming human blood in large quantities is a toxic habit.

Whether you suffer a busted lip and accidentally swallow a few teaspoons of your own blood or if you enjoy spending your free time participating in a macabre lifestyle that teeters too much on the edge of exsanguination for my liking, it’s best we all know what swallowing even a little bit of human blood can mean for our health. Blood may keep us alive while it’s coursing through our veins and keeping our heart pumping, but ingesting it is just like ingesting any other toxin: a little bit probably won’t cause harm, but too much can be life-threatening.

It may seem like a simple question, but what exactly is blood? This red fluid circulating though our blood vessels plays a major role in fighting infections and acts as the body’s transport system. Blood is generally separated into four categories: red blood cells, white blood cells, platelets, and plasma. Hemoglobin, a protein molecule found in red blood cells, contains iron which is responsible for carrying oxygen from our lungs to the rest of the body. Our bodies need iron to function and not having enough can lead to iron deficiency, the most common nutritional deficiency and leading cause of anemia.

The body may need iron to function, but too much can lead to major health complications. People with haemochromatosis, a genetic condition that causes iron to build up in the body to toxic levels, often end up suffering from liver disease and even heart failure. Iron overload can be all too common for some people, considering the human body has trouble excreting the mineral. Vampire bats, on the other hand, come equipped with a mucous membrane in their intestinal tract that prevents too much iron from getting into their bloodstreams.

Like Blaze and Filth, vampire mom Julia Caples has also taken her vampire obsession to the extreme by finding living “donors” who are willing to have the blood sucked straight from their necks. Caples admits that “there's not a lot of nutrition in blood, but maybe there's some value we haven't discovered yet.” More shocking than her alternative lifestyle is how long Caples has been keeping up with her habit of drinking a half a gallon of blood a month: 30 years.

If drinking blood truly is dangerous, how has Caples managed to stay healthy and alive for so long? According to Steven Gruenstein, a hematologist at Mount Sinai Hospital in New York, some people may be drawn to drinking blood due to an iron deficiency or the absence of another mineral.

For anyone who does think their body has adapted to actually need human blood, consider the incredibly high STD rates seen in the U.S. recently.