On Sat, 5 Sep 1998, Mahesh Shah wrote:

> Can this be answered by epidemiological studies? Protein consumption around
> the word versus the incidence of kidney disease?

For a start, here is a clip from a message on the lowcarb list
that discusses some scientific evidence.

   Dr. Marian Blum laid to rest the myth that higher-protein
   diets damage the kidneys in a classic paper published in the
   Archives of Internal Medicine in 1987.  Her research team
   identified adult subjects who currently ate and had eaten a
   high-protein diet - including meat of all kinds - for most of
   their lives and matched them by age and sex to a second group
   of adults who were long-term vegetarians.  The second group
   ...consumed very little protein, and what they did eat was
   entirely of vegetable origin.  The team then measured the
   natural "age-related decline" in kidney function ..and found
   that there was absolutely no difference between the two groups
   across the entire spectrum of ages.  This study shows that
   eating meat or eating a diet of high protein carries with  it
   no risk of damage to normal, healthy kidneys.  A much more
   recent study by the  German research team of Remer and Mantz,
   published in the Journal of Nutritional Biochemistry in 1995,
   showed that weightlifters who consumed excessive amounts of
   protein actually experienced IMPROVED kidney function.

Here's an animal study:

   Hammond KA, Janes DN "The effects of increased protein intake
   on kidney size and function."  J Exp Biol 1998 Jul;201( Pt
   13):2081-2090

   In endothermic vertebrates, long-term increases in metabolic
   energy demand are often associated with increases in food
   intake and accompanied by increases in organ mass. Wide-scale
   increases in organ mass have often been attributed to a
   metabolic response to increased energy intake and utilization.
   On a constant diet, however, increased food intake is also
   associated with increased protein intake. We hypothesized
   that, while increased food intake itself may be responsible
   for increases in digestive tract mass, the consequent
   increased protein intake would be the factor responsible for
   increased kidney mass and function.  Thus, we exposed male and
   female mice to diets differing in protein level (7 %, 15 % or
   46 % casein by mass) at different acclimation temperatures (5
   degreesC or 23 degreesC). Within an acclimation temperature,
   food intake rate remained constant over the entire range of
   dietary protein level, and protein intake rate increased as
   dietary content increased. The mice in the cold-acclimation
   group increased food intake rate by 48-120 % over those in the
   warm-acclimation group. Liver, kidney and stomach mass
   increased with protein intake rate, while digestive tract and
   other vital organ masses increased only in response to
   increased energy intake rate. Blood urea nitrogen levels
   increased with protein intake rate. Glomerular filtration
   rates increased with increases in dietary protein level in
   male mice but not female mice.  Finally nitrogen filtration
   rate increased with protein intake rate for mice on the
   high-protein diet. We suggest that it is primarily the
   increased protein intake rate rather than the increased food
   intake rate that results in the changes in kidney and liver
   mass and kidney function observed to occur in situations of
   high energy demand.


Todd Moody
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