1C Teenagers should probably shower more often than younger kids
because:
Teenagers are more likely to get dirty
Teens have oiler skin
Teens have a stronger sense of smell
Teens are more concerned about their apperance

Of that are from eating black  foods or iron supplements. the most common condition causing  it is a bleeding ulcer.  black poop caused by blood indicate a problem in the upper digestive tract.     along with pain, vomiting, or diarrhea is cause to see a doctor right go see a doctor