how many microbes live on and in the average adult human?

The human body is home to trillions of microbes. The exact number can vary greatly from one person to another, but a commonly cited estimate is that our bodies may contain around 39 trillion bacterial cells compared to 30 trillion human cells. However, this is just an estimate and the actual number could be much higher or lower. These microbes, collectively known as the human microbiota, live on our skin, in our mouths, in our guts, and in other parts of our bodies. They play crucial roles in our health, helping us digest food, producing certain vitamins, and even shaping our immune system.