Laufey Steingrimsdottir Ph.D., of the Landspitali-University Hospital, Reykjavik, and colleagues recruited 2,310 healthy Icelandic adults from February 2001 to January 2003. They divided the adults into three age groups and analogical to theirs calcium intake and serum 25-hydroxyvitamin D level.

“The significance of our study was demonstrated by the strong negative association between sufficient serum levels of 25-hydroxyvitamin D and PTH, with calcium intake varying from less than 800 mg/d to more than 1200 mg/d. Our results suggest that vitamin D sufficiency can ensure ideal serum PTH values even when the calcium intake level is less than 800 mg/d, while high calcium intake (greater than 1200 mg/d) is not sufficient to maintain ideal serum PTH, as long as vitamin D status is insufficient,” say the authors.

“Although a cross-sectional study such as our study is not sufficient to demonstrate causality, the association between vitamin D status, calcium intake, and the interaction between these 2 with serum PTH levels is a strong indication of the relative importance of these nutrients,” the researchers write. There must be more studies to define the ideal intakes. Those should also emphasize the importance of vitamin D status and recommend vitamin D supplements for the general public, when sun exposure and dietary sources are insufficient.

“In conclusion, our study suggests that vitamin D sufficiency may be more important than high calcium intake in maintaining desired values of serum PTH. Vitamin D may have a calcium sparing effect and as long as vitamin D status is ensured, calcium intake levels of more than 800 mg/d may be unnecessary for maintaining calcium metabolism. Vitamin D supplements are necessary to ensure adequate vitamin D status for most of the year in northern climates,” write the authors.

MEDICA.de; Source: American Medical Association (AMA)