Vitamin D Involved in IGF-1 Secretion!?

Even if I repeat myself: The news on vitamin D and its multi-facetted effects on general health and performance are crowding in. The newest study comes from Bogazzi et.al. (Bogazzi. 2010) from the University of Pisa. The scientists found an interesting correlation between serum 25-OH-D levels and the amount of IGF-1 (which is an anabolic hormone involved in muscle building):

A positive relationship was identified between serum 25-(OH) D3 and IGF1 concentrations (r=0.33, p<0.0001); the 25-(OH) D3 -dependent changes of serum IGF-1 concentrations were observed also when subjects were divided on the basis of vitamin D deficiency; in fact, those with severe 25-(OH) D3 deficiency (<20 ng/ml ) had lower (185+/-83 microg/l) IGF1 values than those with mild-to absent 25-(OH) D3 deficit (225+/-83 microg/l, p=0.0004). Conclusions 25-(OH) D3 status may contribute to determine serum IGF1 levels in healthy population.

In spite of that, one must not jump into hasty conclusions, such as "vitamin D supplementation will raise IGF-1 levels", since the observed correlation of vitamin D3 deficiency (which is however pretty common in the western world) and low IGF-1 levels does not prove that there is a causal relationship between the two. It will thus require future studies to vindicate / confute the statement about vitamin D supplementation made at the beginning of this paragraph.