Zach Bush, MD is a renowned, multi-disciplinary physician of internal medicine, endocrinology, hospice care and internationally recognized eduZach Bush, MD is a renowned, multi-disciplinary physician of internal medicine, endocrinology, hospice care and internationally recognized educator on the microbiome as it relates to human health, soil health, food systems, and a regenerative future.cator on the microbiome as it relates to human health, soil health, food systems, and a regenerative future.