I would say Krogan being very durable and having multiple double organs or whatever was phrased as, who were very durable, or hunters. I never picture a Krogan eating a vegan diet so I would say hunters especially since there culture revolved around fighting or strength. But then again, Asia hundreds of years had many wars and conflicts and meat wasn't the primary source of food, and Rome's gladiator were plant based since meat was a luxury and those who were in luxury didn't fight often.