Thus, vitamin D may improve the statin-mediated changes in cardiorespiratory fitness and mitochondrial function by improving the enzymatic machinery involved in oxidative phosphorylation which is blocked by statin. Another proposed mechanism of interaction between statin and vitamin D is inhibition of CYP3A4 by statins, which displays 25-hydroxylase activity in vitro. Vitamin D deficiency leads to 'preferential shunting' of CYP3A4 for hydroxylation of vitamin D, thus decreasing the availability of CYP3A4 for statin metabolism leading to statin-induced toxicity.