Sample size was estimated using iron supplementation data from a study carried out by Scholz-Ahrens et al. (2004) in which a serum ferritin concentration post intervention at 8 weeks (mean ± S.D) of 17.7 ± 11.8 ug/l (Fe fortified milk group) and 10.6 ± 8.1 ug/l (non fortified milk group) was reported. With an effect size of 0.7015447, the total sample size required for each group in the proposed study is 26. Taking into account a 20% drop out rate, the total sample size required is 31 (Power = 0.80). Therefore, the total sample size needed for the whole study is 62. Sample size was estimated using of G Power Software Version 3.1.7.