Nicolaidou et al. showed that vitamin K supplementation was a predictor of u-OC (p < 0.001), c-OC (p = 0.013), carboxy-terminal propeptide of type I procollagen (p < 0.001), and amino-terminal propeptide of type I procollagen (p < 0.001) concentrations in CF subjects17. This evidence concerns the gene COL1A2 and cystic fibrosis.