Thanks, Todd, for this citation (Hammond and Janes J Exp Biol 1998 Jul)

What this indicates to me, is as follows (caution: speculation follows)

1. Kidney function declines with age (fact)

2. High protein diets, esp. with high consumption of fluids, over time
cause the kidneys to increase in mass and in their function. (fact,
right?)

3. By following a high protein, high fat, low carb diet, with plenty of
fluids, our increased kidney function means that we have more kidney
function left later in life, so age related kidney decline affects us
less. (speculation) This is the same logic as a person who has worked
out and built muscle mass and bone mass will maintain this mass longer
through the aging process.

4. Therefore, high protein/low carb diets (paleo style) are healthy and
we can expect to live longer and healthier on them due to better kidney
function.

--Richard