High phosphorus intakes acutely and negatively affect Ca and bone metabolism in a dose-dependent manner in healthy young females

• Published in: British journal of nutrition Vol. 96; no. 3; pp. 545 - 552
• Main Authors: Kemi, Virpi E., Kärkkäinen, Merja U. M., Lamberg-Allardt, Christel J. E.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.09.2006
• Subjects: administration & dosage; Adult; adults; Alkaline Phosphatase; Alkaline Phosphatase - blood; analogs & derivatives; Biological and medical sciences; biomarkers; Biomarkers - blood; blood; blood chemistry; Bone and Bones; Bone and Bones - metabolism; bone formation; Bone metabolism; bone resorption; Bone Resorption - blood; calcium; Calcium - blood; Calcium - metabolism; Collagen Type I; Collagen Type I - blood; Diet; Dietary Supplements; dosage; dose response; Dose-Response Relationship, Drug; Dose–response study; Essential nutrients; Feeding. Feeding behavior; Female; Food additives; Fundamental and applied biological sciences. Psychology; Health care; hormone secretion; Human subjects; Humans; Metabolism; nutrient intake; nutrient-nutrient interactions; Nutrition; Osteogenesis; Osteogenesis - physiology; Osteoporosis; Parathyroid hormone; Parathyroid Hormone - blood; Peptides; Peptides - blood; Phosphatase; Phosphates; Phosphates - blood; Phosphates - urine; Phosphorus; Phosphorus - administration & dosage; Phosphorus intake; physiology; urine; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vitamin D; Vitamin D - analogs & derivatives; Vitamin D - blood; women; United States > US; Finland; Phosphorus intake; Dose–response study; Parathyroid hormone; Bone metabolism; Osteoarticular system; Vertebrata; Mammalia; Parathyroid hormone: Bone metabolism: Phosphorus intake: Dose-response study; Female; Phosphorus; Bone; Metabolism; Dose
• ISSN: 0007-1145; 1475-2662
• DOI: 10.1079/BJN20061838

Ca and P are both essential nutrients for bone and are known to affect one of the most important regulators of bone metabolism, parathyroid hormone (PTH). Too ample a P intake, typical of Western diets, could be deleterious to bone through the increased PTH secretion. Few controlled dose–response studies are available on the effects of high P intake in man. We studied the short-term effects of four P doses on Ca and bone metabolism in fourteen healthy women, 20–28 years of age, who were randomized to four controlled study days; thus each study subject served as her own control. P supplement doses of 0 (placebo), 250, 750 or 1500mg were taken, divided into three doses during the study day. The meals served were exactly the same during each study day and provided 495mg P and 250mg Ca. The P doses affected the serum PTH (S-PTH) in a dose-dependent manner (P=0·0005). There was a decrease in serum ionized Ca concentration only in the highest P dose (P=0·004). The marker of bone formation, bone-specific alkaline phosphatase, decreased (P=0·05) and the bone resorption marker, N-terminal telopeptide of collagen type I, increased in response to the P doses (P=0·05). This controlled dose–response study showed that P has a dose-dependent effect on S-PTH and increases PTH secretion significantly when Ca intake is low. Acutely high P intake adversely affects bone metabolism by decreasing bone formation and increasing bone resorption, as indicated by the bone metabolism markers.