Zinc or multiple micronutrient supplementation to reduce diarrhea and respiratory disease in South African children: a randomized controlled trial.  Luabeya et al., 2007 [276]  South Africa  Over 370 children from a rural community  Vitamin A vs. zinc 10 mg/day + vitamin A vs. a multi micronutrients supplement, from 6 to 24 months of age  No reduction in diarrhea and respiratory morbidity.