Original Communication
European Journal of Clinical Nutrition (2005) 59, 311–317. doi:10.1038/sj.ejcn.1602074 Published online 26 January 2005
A 7-week reduction in salt intake does not contribute to markers of bone metabolism in young healthy subjects
Guarantor: C Lamberg-Allardt.
Contributors: CL-A, MUMK, MR and EP designed the study. A-MN undertook the protocol and collected the data. A-MN wrote the manuscript with the help of CL-A and undertook the statistical analyses with help from MUMK. All contributed to the manuscript.
A -M Natri1, M U M Kärkkäinen1, M Ruusunen2, E Puolanne2 and C Lamberg-Allardt1
- 1Department of Applied Chemistry and Microbiology, Division of Nutrition, University of Helsinki, Finland
- 2Department of Food Technology, Division of Meat Technology, University of Helsinki, Finland
Correspondence: C Lamberg-Allardt, Department of Applied Chemistry and Microbiology, Division of Nutrition, Calcium Research Unit, University of Helsinki, PO Box 66, FIN-00014 Helsinki, Finland. E-mail: christel.lamberg-allardt@helsinki.fi
Received 15 October 2003; Revised 16 August 2004; Accepted 10 September 2004; Published online 26 January 2005.
Abstract
Background:
Sodium intake increases urinary calcium excretion and may thus lead to negative calcium balance and bone loss.
Objective:
We hypothesised that reducing sodium intake would reduce urinary calcium excretion and have a beneficial influence in bone metabolism.
Design:
A total of 29 subjects, 14 males and 15 females, were divided into two study groups. One group (low-sodium group (LS)) reduced sodium intake for 7 weeks by substituting low- salt alternatives for the most important dietary sources of sodium. The other group, serving as a control group (C), was given the same food items in the form of normally salted alternatives. Fasting serum samples as well as 24-h urine samples were obtained in the beginning and at the end of the study. Urinary sodium, urinary calcium, urinary creatinine, serum calcium, serum phosphate, serum creatinine, serum parathyroid hormone (s-PTH), serum C-terminal telopeptides of Type-I collagen and serum bone alkaline phosphatase (s-B-ALP) were analysed.
Results:
The LS group showed a significant decline (P=0.001) in urinary sodium/creatinine ratio without a significant effect on urinary calcium/creatinine ratio. In the LS group, s-PTH increased (P=0.03). The C group showed an increase in s-PTH (P=0.05) and in s-B-ALP, but no differences were observed between the study groups in the changes of serum markers of calcium and bone metabolism.
Conclusions:
We have shown that reducing the sodium intake of young, healthy people with adequate calcium intake over a 7-week period does not affect the markers of bone metabolism.
Sponsorship:
The study was supported by Tekes—National Technology Agency of Finland.
Keywords:
osteoporosis, bone metabolism, sodium, calcium, urinary excretion, PTH
