Dr. Luc (Luke) van Loon

So it's interesting to realize that all tissues, all living tissues, so also skeletal muscle tissue, is constantly being synthesized and broken down.

And that is always hard to imagine that every tissue in your body is breaking down, building up again.

So all the constituents are constantly being renewed, remobilized, refurnished.

And so for muscle, that happens at a rate of 1% to 2% per day.

which means that in say 50 to 100 days you have completely renewed your muscle

And so that renewal is actually one of the factors that makes it able to adapt to its use, to become bigger if you become a bodybuilder or become smaller when you actually don't move around anymore.

So that dynamic, that is why we, yeah, that's what tissue is.

And that tissue requires constant renewal and therefore it needs protein, or at least the building blocks of proteins being the amino acids.

Yeah, that's always, that is a lecture on itself.

So in the past, people did a lot of nitrogen balance studies.

So amino acids contain nitrogen, and so nitrogen goes into the body as protein, and nitrogen also leaves the body as nitrogen, but then as urea or in the urine.

And so measuring the balance between what goes into the body and what leaves the body gives a nice way of seeing whether you're in a positive balance, a negative balance, or a neutral balance.

So what they've done in the past is basically give people a low protein content diet for one or two weeks, a moderate or a high amount of protein, and then see whether you become in a positive or negative balance.

And the assumption is if you're in a neutral balance, it's good.

And if you actually give a low protein diet, you go down to 0.66, then you actually can stay in, most people actually stay in a neutral balance.

And then they suggest that with some leverage on top, we actually get to the 0.8 grams.

But that is, I regard that as a minimal requirement to stay in balance on the diet that has been provided for one to two weeks.

And that's a little bit an issue because, first of all, there's some methodological issues with nitrogen balance.

It's difficult to really figure out how much nitrogen goes in because people always under-report what they're eating.

And the second part is there's also some nitrogen leaving the body that you don't measure, for example, in air or if you fight a skin.