Sometimes improved by zinc picolinate. See: Sakai F, Yoshida S, et al. Therapeutic efficacy of zinc picolinate in patients with taste disorders. Nihon Jibiinkoka Gakkai Kaiho 1995. Picolinic acid secreted by pancreas is the “zinc binding ligand” for intestinal absorption. Other forms of zinc not effective. Consider 50mg daily for a few months to see if it works.