Re: Why does a diet excessively high in protein cause calcium depletion?

Lisa,


I know that high-protein diets put a strain on the kidneys in their attempt 
to excrete the excess waste matter that is the product of protein 
metabolism. I couldn't find a specific answer to your question, but I would 
guess that it is something like this. The kidneys basically filter out and 
keep the blood proteins and cells and "excrete" everything else, and then 
recover all the nutrients (glucose, vitamins, minerals like potassium and 
calcium, etc) from what goes through the filter except what they don't 
want, ie, urea and other waste products. Everything that is recovered is 
recombined with blood proteins and cells and put back into circulation. So 
the "loss" of things like urea, calcium, and potassium is passive and the 
recovery is active. I suspect that one of the things that happens when the 
kidneys are strained is that they operate at less than their usual 
efficiency and aren't as good as recovering the things like calcium that 
the body needs, but the passive loss of those things has nothing to do with 
how well the kidneys are functioning. Thus the loss of calcium stays the 
same but the recovery decreases, and overall you have calcium depletion.

Again, this is a total guess on my part because I couldn't find any 
information on this sort of thing myself. This may be completely more work 
than you want to do, but you could call a local hospital or medical school 
and get connected to the renal/nephrology department and ask one of them as 
well.