Soul Essence

Soul Essence is the substance that Dhampirs feed on. It is present in all bodily fluids but is most apparent in blood. Sweat contains the least amount of Soul Essence. It is stated that all the races possess Soul Essence, but the races upon the seventh place of the Exceed have a more powerful concentration, making the Dhampir disappear if they consume it.

When Sora and Shiro first meet Plum, he licks the sweat off the bottom of Shiro's foot in order to avoid dying of starvation. Soul Essence