Low calcium:phosphorus ratio in habitual diets affects serum parathyroid hormone concentration and calcium metabolism in healthy women with adequate calcium intake.
Excessive dietary P intake alone can be deleterious to bone through increased parathyroid hormone (PTH) secretion, but adverse effects on bone increase when dietary Ca intake is low. In many countries, P intake is abundant, whereas Ca intake fails to meet recommendations; an optimal dietary Ca:P ratio is therefore difficult to achieve. Our objective was to investigate how habitual dietary Ca:P ratio affects serum PTH (S-PTH) concentration and other Ca metabolism markers in a population with generally adequate Ca intake. In this cross-sectional analysis of 147 healthy women aged 31-43 years, fasting blood samples and three separate 24-h urinary samples were collected. Participants kept a 4-d food record and were divided into quartiles according to their dietary Ca:P ratios. The 1st quartile with Ca:P molar ratio < or = 0.50 differed significantly from the 2nd (Ca:P molar ratio 0.51-0.57), 3rd (Ca:P molar ratio 0.58-0.64) and 4th (Ca:P molar ratio > or = 0.65) quartiles by interfering with Ca metabolism. In the 1st quartile, mean S-PTH concentration (P = 0.021) and mean urinary Ca (U-Ca) excretion were higher (P = 0.051) than in all other quartiles. These findings suggest that in habitual diets low Ca:P ratios may interfere with homoeostasis of Ca metabolism and increase bone resorption, as indicated by higher S-PTH and U-Ca levels. Because low habitual dietary Ca:P ratios are common in Western diets, more attention should be focused on decreasing excessively high dietary P intake and increasing Ca intake to the recommended level.
Calcium Research Unit, Department of Applied Chemistry and Microbiology, PO Box 66, FI-00014 University of Helsinki, Helsinki, Finland.
Virpi E
VE
Kemi
Merja U M
MU
Kärkkäinen
Hannu J
HJ
Rita
Marika M L
MM
Laaksonen
Terhi A
TA
Outila
Christel J E
CJ
Lamberg-Allardt
D000328:Adult; D050071:Bone Density Conservation Agents / Q000008:administration & dosage / Q000378:metabolism* / Q000652:urine; D001862:Bone Resorption / Q000097:blood / Q000378:metabolism; D002118:Calcium / Q000008:administration & dosage / Q000378:metabolism* / Q000652:urine; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000378:metabolism*; D003430:Cross-Sectional Studies; D004032:Diet / Q000009:adverse effects*; D015930:Diet Records; D005260:Female; D006706:Homeostasis; D006801:Humans; D018977:Micronutrients; D008903:Minerals; D009752:Nutritional Status; D010024:Osteoporosis / Q000517:prevention & control; D010281:Parathyroid Hormone / Q000097:blood*; D016226:Phosphorus, Dietary / Q000008:administration & dosage / Q000009:adverse effects* / Q000378:metabolism; D012016:Reference Values
D050071:Bone Density Conservation Agents; D002136:Calcium, Dietary; D018977:Micronutrients; D008903:Minerals; D010281:Parathyroid Hormone; D016226:Phosphorus, Dietary; D002118:Calcium