We read with interest the article by Fenton et al (1) in the October 2008 issue of the Journal.
The authors obtained 2 equations from their meta-analysis on the basis of whether urine
was acidic (pH, 6.5) or alkaline. For acidic urine, they estimated that a 47-mEq change in net
acid excretion (NAE) would result in a change in urinary calcium excretion of 1.6 mmol (ie, a
decrease in NAE of 47 mEq would result in a decrease in calcium excretion of 1.6 mmol). If
the urine was alkaline, then the change in calcium excretion would be 1.1 mmol for a …

Background: The acid-ash diet hypothesis of osteoporosis suggests that acid from the
modern diet causes a demineralization of the skeleton, and mobilized bone calcium is
excreted. A systematic approach has not been used to summarize the findings of the
numerous studies about the hypothesis. Objectives: The purpose of this meta-analysis was
to estimate the quantity of net acid excretion and calciuria associated with the modern diet,
to assess the association between acid excretion and calcium excretion, and to assess the …