I recently lowered my cholesterol through dietary changes, since I already was exercising regularly. There is no way to know which change actually helped my numbers, but I do eat a bowl of cereal with 3g soluble fiber every morning (mine is Kashi GoLean but there are others, or oatmeal).
I agree with the other posters that you need to make the changes gradually. Perhaps he can try to add a new healthy habit every week or two. Good luck!
For you to be here now, trillions of drifting atoms had somehow to assemble in an intricate and intriguingly obliging manner to create you. It's an arrangement so specialized and particular that it has never been tried before and will only exist this once.
--Bill Bryson, "A Short History of Nearly Everything"