Nguyen Xuan Ninh in 2014 supplemted 400 IU of Vitamin D2 (Ergosterol) fortified in biscuits for primary schoolers 5 days / week during 4 months, results showed that mean Vitamin D concentration in the intervention higher than that of the control (26.1±6.4ng / ml vs 21.5±3.5ng / mL) (p<0.001).