The microbiome plays an important role in human health and disease. Our current understanding of the human microbiome is limited. A significant amount of progress has been made in this area of research in the last two decades. The human microbiome plays an important role in host metabolism and physiology. Recent studies suggest a critical relationship between the human microbiome and host metabolism. The interactions between the microbiome and host metabolism affect human health and disease. However, this review of the literature indicates that more studies are required using new technologies to have a greater understanding of the role the human microbiome plays in human health and disease.