diet, high-risk kidneys
Popular low-carbohydrate, high-protein
diets may result in rapid weight loss, but they also appear to pose serious health
problems, including increased risk of kidney stones and bone loss," report
researchers from the University of Chicago and the University of Texas Southwestern
in the August American Journal of Kidney Diseases.
study was too brief to show such a diet induced osteoporosis, but our data suggests
this may be another potential risk," says Shalini Reddy, assistant professor
of medicine and the study's lead author.
eight-week study, which was funded in part by the U.S. Public Health Service,
ten healthy subjects ate a regular diet for two weeks. They followed that with
two weeks on a highly restrictive diet that included some vegetables but no fruits
and fewer than 20 grams of carbohydrates. Participants then ate a slightly less
restrictive diet for the final four weeks.
heavy on animal proteins and light on carbohydrates-like the Atkins diet-does
increase fat metabolism, which can boost the amount of acid in the blood. The
researchers found that acid excretion-a marker for the blood's acid load-increased
as much as 90 percent while subjects were on diets that severely restricted carbohydrates.
Meanwhile, calcium absorption was unchanged, but calcium excretion increased.
And with higher levels of uric acid and calcium
to handle, kidneys tend to form stones. More acid in the blood also may suppress
the cells that make new bone and stimulate the cells that break down bone. Therefore,
much of the excreted calcium likely was leached from bone. - John Easton