Vitamine D voor goede botten*
Uit een Australische studie blijkt dat extra vitamine D noodzakelijk is voor gezonde botten zeker op de langere termijn. De studie werd opgezet om te kijken of in een zonnig land als Australië extra vitamine D ook invloed heeft op de botdichtheid. In de studie kregen vrouwen van tussen de 70 en 80 jaar vijf jaar lang dagelijks 1 tablet van 1.200 mg
calcium plus een placebo, of 1 tablet calcium plus 1 tablet van 25 mcg vitamine D of 2 placebo tabletten. Na 1 jaar bleek dat zowel bij de vrouwen in de alleen calciumgroep als in de calcium + vitamine D groep de botdichtheid niet veranderd was
in tegenstelling tot de dubbel placebogroep. Doch na 3 en na 5 jaar bleek dat de botdichtheid alleen in de vitamine D groep onveranderd was. Zowel in de
alleen calciumgroep als de dubbel placebogroep was de botdichtheid afgenomen.
Effects of calcium and vitamin D supplementation on hip bone mineral density and calcium-related analytes in elderly ambulatory Australian women: a 5-year randomized controlled trial
Kun Zhu, Amanda Devine, Ian M. Dick, Scott G. Wilson, and Richard L. Prince*
School of Medicine and Pharmacology, University of Western Australia, Perth, Australia (KZ, AD, IMD, RLP); Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Perth, Australia (KZ, IMD, SGW, RLP), School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Perth, Australia (AD)
* To whom correspondence should be addressed. E-mail: rlprince{at}cyllene.uwa.edu.au
Context: Effects of long term calcium with or without vitamin D on hip bone mineral density and bone turnover in sunny climates have not been reported.
Objective: Evaluation of vitamin D added to calcium supplementation on hip DXA BMD and calcium related analytes.
Design, setting and participants: A five-year randomised controlled double-blind trial of 120 community-dwelling women aged 70–80 years.
Interventions: Calcium 1200 mg/d with placebo (Ca group) or 1000 IU/d vitamin D2 (CaD group), or double placebo (control).
Main outcome measures: Hip BMD, plasma 25OHD, biomarkers of bone turnover, PTH and intestinal calcium absorption.
Results: Hip BMD was preserved in CaD (-0.17%) and Ca (0.19%) groups but not controls (-1.27%) at year one and only maintained in the CaD group at years 3 and 5. The beneficial effects were mainly in those with baseline 25OHD levels below the median (68 nmol/L). At year one, compared with controls, Ca and CaD groups had 6.8% and 11.3% lower plasma alkaline phosphatase, respectively (P 0.02), and 28.7% and 34.5% lower urinary DPD/Cr ratio, respectively (P 0.05). At 5 years, this suppression was only maintained in the CaD group. CaD reduced PTH at 3 and 5 years cf controls (27.8 and 31.3%, P 0.005) in those with baseline PTH levels above the median (3.6 pmol/L). Therapy did not affect intestinal calcium absorption at high carrier loads.
Conclusions: Addition of vitamin D to calcium has long term beneficial effects on bone density in elderly women living in a sunny climate, probably mediated by a long term reduction in bone turnover rate.
SOURCE: Journal of Clinical Endocrinology and Metabolism (Februari
2008)
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