Do our cells replace themselves every seven years?

G’day to you. Wonderfully clear and warm (=hot) day here in the Kingdom. Great to see you. Pull up a doughnut and sit down. Coffee’s fresh. Say…I’m sure you’ve heard that our bones replace themselves every seven years, right? Well, some folks say that all our cells do the same and that essentially we become a new person every seven years. With me so far? So what’s the truth, eh?  If I, like, become a new person every seven years, who is the old fellow keeps smiling at me in the mirror. He ain’t getting any younger! Maybe I’m just getting new wrinkle cells.

True enough that cells only live so long and when they die, they are replaced with new ones.  We have between 50 and 75 trillion cells in our bodies. Different types of cells have different life spans. In fact, when a human passes on, some cells may live on for hours – even days.

Red blood cells live for about four months.

White blood cells live on average more than a year.

Skin cells live about two or three weeks.

Colon cells live about four days.

Sperm cells have a life span of only about three days.

Brain cells usually live for our whole lives although some, such as neurons in the cerebral cortex are not renewed when they die.

As for the seven year cycle, well, that idea has been floating around for a long time but there does not appear to be any scientific evidence to confirm it. However, most of the atoms in our bodies are in a constant state of flux and there is evidence that most of our cells regenerate within 15 years or so.

So according to that, and applying Taylor’s Radical Youth Theory, we should all be no more than 15 years old, eh! Can I borrow your bike? What’s a bike? A carrier for a mobile Gameboy?

See ya!

Bob

Comment from Dennis in Toronto:

Hi Bob!

Read an article on eggs a month or so ago. The bottom line was only a very small number (5, or 20, or whatever) of people in the US die of Salmonella each year. I like my yolks runny, so I'll take my chances.

All the best.

Bob’s reply:

One of the late night snacks here in Thailand is a steaming bowl of rice soup with either pork or chicken in it. A favourite addition is to crack an egg into the hot soup. I suppose it cooks to some degree. Oh, other additions include a tsp. of fish sauce with chillies, a tsp.pf vinegar with larger chillies, a tsp. of crushed chillies and a tsp. of sugar… usually a tsp.of each. I don’t add the sugar.

Comment from Robin in Farnborough, England:

Jen really enjoys your blogs so could you include her on your list, on her i-pad.

Bob’s reply:

On her I-Pad no less! Must be nice… Happy to have Jen on my ever-growing list of loyal readers. Going to have to syndicate soon but only if it pays me money, eh!