Black Stool Pomegranate My Stool Is Black?!?!?!?!?!?!?

My stool is black?!?!?!?!?!?!? - black stool pomegranate

Well, I drink V8 juice, pomegranate and blueberry-type, and my chair was black, I noticed that my brother is 4 years old, black stools can also be our food? or something more serious.