Revised Estimates for the Number of Human and Bacteria Cells in the Body

Summary

Reported values in the literature on the number of cells in the body differ by orders of magnitude and are very seldom supported by any measurements or calculations. Here, we integrate the most up-to-date information on the number of human and bacterial cells in the body. We estimate the total number of bacteria in the 70 kg "reference man" to be 3.8·1013. For human cells, we identify the dominant role of the hematopoietic lineage to the total count (≈90%) and revise past estimates to 3.0·1013 human cells. Our analysis also updates the widely-cited 10:1 ratio, showing that the number of bacteria in the body is actually of the same order as the number of human cells, and their total mass is about 0.2 kg.

Related articles

• Evolutionary Tree for All Bumblebee Species World-Wide Estimated by Combining Information from Fast-Evolving Genes, Slow-Evolving Genes, and Genomic Data (Apidae, Bombus)

  This article presents a comprehensive evolutionary tree for all extant bumblebee species worldwide, integrating data from fast- and slow-evolving genes along with genomic information to enhance understanding of their evolutionary relationships.

• Pollination ecology in the tropical Andes: moving towards a cross-scale approach

  This review explores plant-pollinator interactions in the tropical Andes, highlighting the importance of these networks for ecosystem functioning and suggesting a cross-scale approach to improve research and conservation efforts in this critical biodiversity hotspot.

• Helminths Overview - Notes Studley Microbiology & Parasitology

  This document provides a comprehensive overview of helminths, including their life cycles, classification, and significant types affecting humans. It covers their diagnosis, clinical presentations, and treatments for various infections caused by these parasitic worms.

• Life Processes

  This chapter explores the defining characteristics of life, the processes necessary for living organisms to maintain their structures, and the critical functions of nutrition, respiration, and excretion. It discusses both autotrophic and heterotrophic nutrition while highlighting the importance of molecular movements for sustaining life.

• Nuclear Magnetic Resonance (NMR) Fundamentals and Applications

  This document covers the principles of nuclear magnetic resonance (NMR), including the behavior of atomic nuclei in magnetic fields, gyromagnetic ratios, and the applications of NMR in spectroscopy.