A 2014 study by the Department of Forensic Medicine at the MedUni Vienna, with the Department of Anthropology at the Institute of Forensic Medicine at the University of Bern confirms the authenticity of many historical claims which indicates that Roman Gladiators had a special diet rich with barley and legumes. In contemporary literature, they were referred to as "hordearii" ("barley eaters”).
The study came to such a conclusion following the detailed bone analysis of 53 individuals, 22 of whom were gladiators, known for being some of the most elite athletes of the Roman Empire. These bone fragments were some 1,800 years old and found in the Roman town of Ephesus which is situated in modern-day Turkey and once was the capital of the Roman province of Asia with over 200,000 inhabitants.
In this study, using spectroscopy, stable isotope ratios (carbon, nitrogen, and sulfur) were investigated in the collagen of the bones, along with the ratio of strontium to calcium in the bone mineral. The results of the study made the research team conclude that the gladiators mostly ate a vegetarian diet and also use to have a special potion made of plant ash which made them have a considerably higher amount of strontium in their bones.
This further lead the conclusion that gladiators had a higher intake of minerals from a strontium-rich source of calcium, which can come from drinking a sort of plant-ash beverage (references to which are also found in various historical texts).
Sandra Lösch, Negahnaz Moghaddam, Karl Grossschmidt, Daniele U. Risser, Fabian Kanz. Stable Isotope and Trace Element Studies on Gladiators and Contemporary Romans from Ephesus (Turkey, 2nd and 3rd Ct. AD) - Implications for Differences in Diet. PLoS ONE, October 15, 2014 DOI: 10.1371/journal.pone.0110489