Mineral water as a source of dietary calcium: acute effects on parathyroid function and bone resorption in young men.
BACKGROUND
Calcium is a major component of mineralized tissues and is required for normal growth and maintenance of bone. Epidemiologic studies showed that a large percentage of the population fails to meet the currently recommended guidelines for optimal calcium intake.


OBJECTIVE
The present study was designed to determine whether high-calcium mineral water is an efficient additional source of dietary calcium.


METHODS
Twelve healthy young men (mean +/- SD age: 21.1 +/- 1.2 y) ingested in a randomized order either 0.5 L of a mineral water containing 344 mg Ca/L or 0.5 L of a mineral water with a very low concentration of calcium (<10 mg/L) as a control. Blood samples were drawn before and 1, 2, 3, and 4 h after intake of the water. Urine was collected for 2 h before and every 2 h for 4 h after ingestion of the water. Serum concentrations of intact parathyroid hormone (iPTH) and serum concentrations and urinary excretion of a recently developed biochemical marker of bone resorption, type 1 collagen cross-linked C-telopeptide (CTx), were measured.


RESULTS
Serum iPTH was significantly (P < 0.002) lower after ingestion of high-calcium water than after ingestion of the control. There was a significant (P = 0.01) progressive decrease in urinary CTx after ingestion of the high-calcium water, whereas after ingestion of low-calcium water the changes were modest and not significant. The fall in serum CTx concentrations was 34.7% 3 h after ingestion of high-calcium water, compared with 17.6% with the control. The decreases in serum CTx concentrations were significantly (P < 0.05) lower 1, 2, 3, and 4 h after ingestion of high-calcium water than after ingestion of the control.


CONCLUSIONS
The present study showed that one oral intake of water containing a very moderate dose of calcium (172 mg) acutely inhibited iPTH secretion and bone resorption.
Guillemant
J
J
Service de Biochimie, Faculté de Médecine Pitié-Salpêtrière, Paris. guillema@ccr.jussieu.fr
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Arnaud
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Guillemant
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D000328:Adult; D001862:Bone Resorption / Q000517:prevention & control*; D002136:Calcium, Dietary / Q000008:administration & dosage*; D003094:Collagen / Q000097:blood / Q000652:urine; D024042:Collagen Type I; D006801:Humans; D007700:Kinetics; D008297:Male; D008900:Mineral Waters / Q000008:administration & dosage*; D010280:Parathyroid Glands / Q000187:drug effects / Q000502:physiology*; D010281:Parathyroid Hormone / Q000097:blood; D010455:Peptides / Q000097:blood / Q000652:urine
D002136:Calcium, Dietary; D024042:Collagen Type I; D008900:Mineral Waters; D010281:Parathyroid Hormone; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D003094:Collagen