L.C.
I have a friend who has recently cut out meat from most of the food she feeds to her family. They are eating a lot more veggies. Her husband swears that his hair is growing in much thicker than it was before. (He is still fairly young though--in this late 30's.)
I have another friend who has been making veggie/fruit/kale smoothies for herself and her husband (mid-60's) and he has said that his hair is growing in more too!
It probably takes a couple months to see any results, but you might want to try reducing his meat consumption (eating lots of animal protein is linked to hair loss) and adding more veggies to his diet. Even if it doesn't add hair to his head, at least he will have been eating a healthy diet. Good luck!