Diet (6)
'diet' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for intake that I've seen before include "New recruits" , "Fresh pupils" , "Group of new students" , "Number of acceptances as in school" , "Entry for air, etc" .)
(Other definitions for nutrition that I've seen before include "what's taken in?" , "Food, nourishment" , "Act of nourishing" , "Food and drink, edibles" , "Food, its study" .)