That depends on what they are already consuming. Researchers in Mexico feel that nutritional supplements are good for some babies and very young children since they complement nutrients they get from other sources. Their new study assessed how introducing different types of supplements changed eating habits and in certain cases improved the nutrition of infants.
They studied amount of calories (to increase growth) and nutrient intake among babies aged 6–12 months old who received one of three nutritional supplements. Urban communities were randomly given one of the following: a milk-based fortified formula, a micronutrient powder, or micronutrient syrup. Each supplement was fortified with the same micronutrients. Dietary intake was estimated using a questionnaire for parents to find out how much the child ate/drank prior to supplementation. The study found that children in the milk-based fortified food group ate/drank less calories, protein and nutrients than those in the micronutrient powder/syrup groups. The researchers said, “Given the differences in calorie consumption among the three supplemented groups, it can be concluded that supplementation with micronutrient powders is an adequate addition for urban children who have already met their minimum calorie and protein requirements.”
(Gabriela Añorve-Valdez, Amado David Quezada-Sánchez et al., “Fortified food supplementation in children with reduced dietary energy and micronutrients…” Nutrition Journal August 2018, 17:76) https://nutritionj.biomedcentral.com/articles/10.1186/s12937-018-0385-3