I know that we can say something is helpful to/for someone like in
“This information would be extremely helpful for/to teenagers.”
I wonder if it is okay to say something is helpful to/for something
For example, let’s say I am teaching someone a particular exercise; can I say either of these sentences to him to mean that that exercise is effective for his stomach:
This is a helpful exercise for your abdomen.
This is a helpful exercise to your abdomen.
Or let’s say I think a book is effective at improving kids’ imagination, can I say either of these:
“This book is helpful for kids’ imagination.”
“This book is helpful to kids’ imagination.”
I am asking this question because I can’t find the structure “helpful to something” in dictionaries and that structure sounds a little bit off to me - especially when I put “to” instead of “for” after “helpful.”