There Are More Bacteria in Your Body Than Human Cells

You are, in a very real sense, more microbe than human. Recent scientific estimates suggest the average human body contains approximately 38 trillion bacterial cells, outnumbering our roughly 30 trillion human cells by a small but significant margin. Earlier estimates (like the often-cited 10:1 ratio) were overestimates, but we're still partially outnumbered.

The vast majority of these bacteria live in the gut and play essential roles in digestion, immune function, and even mood regulation. The total weight of your microbiome is approximately 0.2 kg (about the weight of a small apple). Disrupting the microbiome — through antibiotics, poor diet, or illness — can have profound effects on overall health, including mental health.