Also known as Vlad the Impaler, the military ruler is said to have likely killed over 80,000 people, many by impalement, as per historians.
A new chemical analysis of the letters penned by the prince have unravelled details about his health and the environment in which he lived, according to researchers, including Maria Gaetana Giovanna Pittalà from Catania University in Italy.
New research, a set of which published in the journal Analytical Chemistry recently, extracted thousands of fragments of protein molecules from the surface of these letters and isolated about 500 of those that showed signs of degradation, indicating they were over 500 years old.
Researchers isolated a further 100 of the most degraded proteins, which were likely the oldest.
About 16 of these protein molecules were said to be of human origin and had most likely come from Vlad III.
These proteins suggest Vlad III may have suffered from respiratory issues, especially a condition called hemolacria, that may have caused him to cry literal tears of blood.
“He might also have suffered from a pathological condition called hemolacria, that is, he could shed tears admixed with blood,” scientists wrote in the study.
Study co-author Gleb Zilberstein said there was also an absence of animal food proteins among the molecules extracted from the letter.
“Food proteins are found only in plant foods. The prototype vampire may have been a vegan,” Dr Zilberstein told The Times.
If Vlad had been vegetarian or vegan, it may not have been an ethical choice as it is during modern times, scientists said.
Europe had a “very cold climate” during the time Vlad lived, with very little food.
Even aristocrats in Europe reportedly had a very meagre diet at the time, with rare meat consumption.
“Dracula may have been vegetarian or vegan due to poor diet or poor health,” Dr Zilberstein said.
The new findings reveal how similar techniques can shed more light on historical personalities based on documents they authored.
While more medieval people may have touched these documents, the most prominent ancient proteins “should be related to Prince Vlad the Impaler, who wrote and signed these letters”, scientists said.