The included trials were heterogeneous in sample size (range 33 to 2799), duration (range 4 to 24 months), and outcome measures. The lack of benefit of the intervention in studies which found variable percent of subjects with some micronutrient deficiencies at enrolment could be related to some characteristics of the included trials: All studies but that of Avenell [9] had not determined the micronutrients status of the target population before the enrolment. Therefore, the formulas of multivitamin and mineral supplements used were not aimed to correct any pre-specified deficiency. Moreover, those studies had different considerations to define the formula, which explains the large variability of the supplements across the studies. Finally, the assessment of the micronutrient status was also variable across the studies: dietary intake evaluation and/or micronutrients blood concentration, which affects the consistency of this subgroup meta-analysis.