# How many new somatic cells does a person produce every second?

06 September 2016

## Question

As an adult male, 70kg, 45y, in good health, how many new somatic cells do I produce every second? Rbcs don't count! Could this be measured by labelling somehow? What percentage have defects?

The panel give us their guesses on this tricky question. Fortunately, Kat Arney is armed with the facts...

(David) - You're looking at me. You want me to guess.

Kat - Yeah, I want everyone to have a guess.

(David) - There's billions of cells in our body so we're probably making hundreds of thousands every second, 10 to the 5.

Adam - But now we've got one guess. All of our guesses are going to be basically the same because you know, we've anchored the guessing. I'm going higher.

Kat - Andrew?

Andrew - I feel under a little pressure right now.

Kat - You are a biologist.

Andrew - This is not my field of biology. I'm going for a million.

Kat - You're going for a million? A million cells per second.

Caroline - I'm going to go for lower. I remember reading somewhere that you do retain some cells for quite a long time so I'm going to go for tens of thousands rather than hundreds of thousands.

Kat - I've been doing a little bit of maths. Math is not my strong suit but I have been having a little go at this. Your whole body is made up of probably now the best estimates are around this 37 trillion cells in your body. Caroline is right. Some of your cells don't multiply very often, things like your heart muscle doesn't really multiply but then cells like your skin cells, your immune cells your red blood cells, your gut cells, the sort of the epithelia, they really, really, really multiply. It turns out, every single day, roughly, 50 billion cells in an adult will die. Okay, 50 billion of your cells die because there's this turnover, you got to make new cells, got to keep repairing, got to keep renewing. And so, I think every second, there's about 2 million red blood cells made. You'll also have cells being made in your gut, in your skin, so it works out probably if you do the sums, if about 5 million cells are dying every second, it's probably about that many being made every second as well. There's something like 40,000 skin cells in a minute which always makes my flesh crawl.

Caroline - Gosh! I lost that one.