Long-Term Vitamin D3 Supplementation Does Not Prevent Colonic Inflammation or Modulate Bone Health in IL-10 Knockout Mice at Young Adulthood

Inflammatory bowel disease (IBD) is an idiopathic disease that can impair bone metabolism. Low vitamin D status has been implicated in its progress. This study used interleukin (IL)-10 knockout (KO) mice, that develop an intestinal inflammation when housed in a non-sterile environment, to determine if supplementation with vitamin D₃ throughout life could mitigate inflammation and attenuate the lower bone mineral content (BMC) and density (BMD), and bone strength. Female IL-10 KO mice were randomized 25 or 5000 IU vitamin D₃/kg diet throughout pregnancy and lactation. At weaning, offspring received the same or opposite diet as their mother until age three months. Body weight growth was similar among groups within a sex. At three months of age, there were no differences in inflammation and gene expression in the colon of offspring. Male offspring exposed to continuous 25 IU vitamin D₃/kg diet had lower (p < 0.001) colonic VDR expression and those exposed only to low vitamin D₃ until weaning had higher serum IL-6. There were no differences in femur or vertebral BMC, BMD or bone strength. In summary, long-term exposure to vitamin D₃ did not attenuate intestinal inflammation or preserve bone mineral or bone strength. Thus, supplementation with vitamin D₃ does not exert anti-inflammatory effects in this mouse model that mimics human inflammatory bowel disease.