The role of microbiomes in human biology and health are being extensively investigated, yet how the fungal community or mycobiome contributes to an integral microbiome is unclear and probably underestimated. We review the roles of fungi from the perspectives of their functionality in human biology, their cross-kingdom talk with other human microbial organisms, their dependence on diet and their involvement in human health and diseases. We hypothesize that members of the fungal community may interact as necessary symbionts with members of other human microbiome communities, and play a key role in human biology, yet to be fully understood. We propose further that "regulobiosis", whereby fungi play a regulatory role in human ecobiology, is operative in humans as probably obtains in other forms of life. Fungally-dependent regulobiosis would characterise, at first, microbiomes which include, but are not limited to, bacteria, archaea, and viruses; then, their human host; and, next, provide ecological connectedness.