Acute effect of high-calcium milk with or without additional magnesium, or calcium phosphate on parathyroid hormone and biochemical markers of bone resorption.
OBJECTIVE
To assess whether there are any differences in the postprandial physiological responses to apple drink (control), calcium phosphate (tricalcium phosphate, TCP) and high-calcium skim milk (HCSM) with or without additional magnesium in postmenopausal women.


METHODS
Randomized, controlled, cross-over. Measurements after overnight fast before each drink, and subsequently every hour for 8 h postprandially.


METHODS
Human Nutrition Studies Laboratory, Milk and Health Research Centre, Massey University, Palmerston North, New Zealand.


METHODS
Twenty-one healthy postmenopausal women.


METHODS
Four drinks, each 400 ml. (1) Apple drink (25% fruit juice). (2) TCP dispersed in water containing 1200 mg Ca. (3) HCSM containing 1200 mg Ca and 65.5 mg Mg. (4) HCSM containing 1200 mg Ca and 172 mg Mg.


RESULTS
There was no difference in baseline serum calcium, PTH or C-telopeptide levels between drinks. There were no overall differences in serum calcium after apple or after either milk, but after TCP serum calcium increased from a baseline value of 2.12+/-0.08 to a mean peak of 2.21+/-0.12 mmol/l (s.d.) (P=0.0001) after 2 h. There were no significant differences in serum PTH after either apple or HCSM+Mg. In contrast, after TCP, serum PTH decreased from 2.76+/-0.69 to a mean nadir of 2.23+/-0.65 pmol/l (P=0.0001) after 1 h, and after HCSM, it decreased from 2.71+/-0.78 to a mean nadir of 2.51+/-0.87 pmol/l (P=0.007) after 2 h. Serum C-telopeptides decreased after each drink, reaching nadirs after 5 h. At this time the serum values for each of the high calcium drinks were not different from each other, but were significantly less than for apple (P=0.001 for each), being 0.22+/-0.09 ng/ml for apple, 0.15+/-0.08 for TCP, 0.14+/-0.07 for HCSM and 0.16+/-0.07 for HCSM+Mg.


CONCLUSIONS
Despite differences in serum calcium and PTH responses to the three high-calcium drinks that we tested, there was no distinguishable difference in serum C-telopeptides between high calcium drinks.
Green
J H
JH
Milk and Health Research Centre, Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand. J.H.Green@massey.ac.nz
Booth
C
C
Bunning
R
R
D000368:Aged; D000818:Animals; D019540:Area Under Curve; D001682:Biological Availability; D015415:Biomarkers / Q000097:blood; D001862:Bone Resorption / Q000378:metabolism* / Q000517:prevention & control; D002118:Calcium / Q000097:blood / Q000493:pharmacokinetics*; D002130:Calcium Phosphates / Q000008:administration & dosage / Q000494:pharmacology; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000493:pharmacokinetics*; D003094:Collagen / Q000097:blood; D024042:Collagen Type I; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008274:Magnesium / Q000008:administration & dosage / Q000494:pharmacology*; D008875:Middle Aged; D008892:Milk / Q000737:chemistry*; D010280:Parathyroid Glands / Q000187:drug effects / Q000378:metabolism; D010281:Parathyroid Hormone / Q000097:blood*; D010455:Peptides / Q000097:blood; D017698:Postmenopause
D015415:Biomarkers; D002130:Calcium Phosphates; D002136:Calcium, Dietary; D024042:Collagen Type I; D010281:Parathyroid Hormone; D010455:Peptides; C485828:alpha-tricalcium phosphate; C052929:collagen type I trimeric cross-linked peptide; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; D003094:Collagen; C020243:calcium phosphate; D008274:Magnesium; C485829:calcium phosphate, dibasic, anhydrous; D002118:Calcium