Nutritional needs (8)
I believe the answer is:
minerals
'nutritional needs' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for minerals that I've seen before include "Fizzy soft drinks" , "Natural substances in the ground, such as coal" , "non-organic material" , "Neither animals nor vegetables" , "Substances obtained by mining" .)