In my case, the metallic taste began about week 3, and by week 5, everything tasted awful. Chocolate was one of the first things to go in my case, and has yet to come back completely.

I concur with Markus that you cannot let the taste impact his eating. I ate a lot of mashed potatoes with gravy and very finely ground meat. Soups worked well, as did scrambled eggs. I lost 30 pounds, which I should have lost anyway. I started treatment at 238, ended at 208. Could still lose a few . . . ;-)

This is not a diet plan. Your brother needs every calorie he can take in to keep his body strong enough to get through the treatment in good shape and to fight the cancer.

Good luck to you both.