He's going to have to build up his immune system. So I recommend a good juicer. Like an Omega 8004.
Grow and juice wheat grass and barley grass.
BODY CLEANSING: The many detergent factors of wheatgrass juice can drain the lymph system, carrying away many toxins from all body cells. When an imbalance or injury exists (examples: sore tendons or joints; degenerative disease; etc.), there is a natural build-up of mucous in the lymph particular to that area. This mucous is encapsulated, helping to ensure the proper flow of lymphatic fluid. Wheatgrass juice helps to breakdown the mucous and allow it to drain. This helps to relieve pressure and allow healing.