Effect of high vegetable protein diets on urinary calcium loss in middle-aged men and women.
OBJECTIVE
To determine the effect of high-protein diets, which have recently been promoted for their health benefits, on urinary calcium losses and bone turnover in older subjects.


METHODS
Randomized controlled cross-over study.


METHODS
Teaching hospital and university.


METHODS
Twenty hyperlipidemic men and postmenopausal women (age 56+/-2 y) completed the study.


METHODS
One-month test and control phases during which subjects consumed equi-energy metabolic diets high in calcium (1578 and 1593 mg/day, respectively). On the test diet 11% of total dietary energy from starch in the control bread was replaced by protein (wheat gluten), resulting in 27% of energy from protein on the test diet vs 16% on the control diet.


METHODS
Urinary calcium excretion.


RESULTS
Compared with the control diet, at week 4, the test diet increased mean (+/-s.e.m.) 24 h urinary output of calcium (139+/-15 vs 227+/-21 mg, P=0.004). The treatment difference in urinary calcium loss correlated with the serum anion gap as a marker of metabolic acid production (r=0.57, P=0.011). Serum calcium levels were marginally lower 2.41+/-0.02 vs 2.38+/-0.02 mmol/l (P=0.075), but there was no significant treatment difference in calcium balance, possibly related to the high background calcium intake on both diets.


CONCLUSIONS
In the presence of high dietary calcium intakes the vegetable protein gluten does not appear to have a negative effect on calcium balance despite increased urinary calcium loss.
Jenkins
D J A
DJ
Clinical Nutrition and Risk Factor Modification Center, St Michael's Hospital, Toronto, Ontario, Canada. cyril.kendall@utoronto.ca
Kendall
C W C
CW
Vidgen
E
E
Augustin
L S A
LS
Parker
T
T
Faulkner
D
D
Vieth
R
R
Vandenbroucke
A C
AC
Josse
R G
RG
D000328:Adult; D000368:Aged; D002118:Calcium / Q000652:urine*; D018592:Cross-Over Studies; D004032:Diet; D004044:Dietary Proteins / Q000097:blood / Q000494:pharmacology* / Q000652:urine; D005243:Feces; D005260:Female; D006801:Humans; D006949:Hyperlipidemias / Q000097:blood / Q000652:urine; D008297:Male; D008875:Middle Aged; D017698:Postmenopause / Q000652:urine; D014675:Vegetables
D004044:Dietary Proteins; D002118:Calcium