Vlad the Impaler was not a nice guy. You don't earn the nickname "The Impaler" because of all your charity work. But new research suggests that, as well as possibly crying tears of blood, the figure often thought to have inspired Bram Stoker's Dracula may have been vegetarian or vegan.

Vlad, or Mr Impaler if you'd prefer, ruled over Wallachia and gained his unsavory reputation through his brutality against his enemies. It's estimated that he may be responsible for up to 80,000 deaths during his lifetime, impaling a good number of them on spikes, perhaps even eating amongst them as they suffered and died. 

According to a chemical analysis of three letters written in 1457 and 1475 by Vlad, however, it's possible animals were not harmed for this horrible banquet. The letters – addressed to the ruler of the city of Sibiu, Thomas Altemberger, and discussing matters like tax collection – were sampled using ethylene-vinyl acetate (EVA), a method that doesn't appear to cause damage or contamination.

“[W]e characterized about 500 peptides, of which about 100 peptides were certainly of human origin," the authors wrote in their study. “Peptides related to blood proteins or coming from proteins involved in the respiratory system were identified in all the documents characterized.”

Analyzing these closely, they found some peptides related to proteins involved in ciliopathy, a genetic disorder. They also found signs of retinal diseases and inflammatory processes. 

"Although proteomics data cannot be considered exhaustive alone, altogether, these identifications might indicate that Dracula 'cried tears of blood'," they wrote, "i.e., he suffered from the condition of hemolacria, as reported by some stories."

Interestingly, the team found an absence of animal food proteins when analyzing the letters.

“Food proteins are found only in plant foods," study co-author Gleb Zilberstein told The Times. "The prototype vampire may have been a vegan."

However, this was likely not an ethical thing. You impale that many people, you probably aren't going to get too squeamish in KFC. According to the authors, meat was meagre at the time and it could have been down to a lack of choice, or his own poor health. Nevertheless, it's possible that the figure behind the bloodthirsty Dracula was more partial to a salad.

The study is published in the journal ACS Analytical Chemistry.