Unflavored Powdered Multivitamin in Children

The goal of this clinical trial is to learn whether a daily unflavored powdered multivitamin (EllaOla Kids Essentials) improves mood and behavior in children aged 4 to 11 who are picky eaters and experience behavioral challenges. Researchers will also look at whether the multivitamin affects overall health, well-being, nutrition, and serum vitamin levels, and whether it is safe and well tolerated. The main questions it aims to answer are: Do more parents of children taking the multivitamin report a clinically meaningful improvement in their child's overall mood and behavior after 12 weeks than parents of children taking a placebo? Does the multivitamin change parent-reported emotional reactivity, overall health and well-being, and nutrition over 12 weeks? In children who take part in optional at-home blood testing, does the multivitamin improve serum vitamin D and vitamin B12 levels? Researchers will compare the multivitamin to a placebo (a look-alike powder made of tapioca fiber that contains no vitamins) to see if it improves mood and behavior. Participants will: Be randomly assigned to receive either the multivitamin or the placebo. Neither the families nor the study team will know which one the child gets. Have a parent or caregiver mix the powder into the child's food or drink once a day at home for 12 weeks. Have a parent or caregiver complete short online questionnaires about the child's mood, behavior, health, and nutrition at baseline and at Weeks 2, 4, 6, 8, and 12, using a smartphone app. All study visits are remote. Choose whether to do an optional at-home blood collection at the start and at Week 12. Choose whether to continue in an optional 12-week open-label extension (Weeks 12-24), where all children, including those who were on placebo, receive the multivitamin.

Inclusion Criteria: 1. Healthy child aged 4-11 years at time of enrollment, male or female 2. Not currently taking oral over-the-counter supplements or another multivitamin, if they are taking, must discontinue use for at least four weeks prior to randomization and for the duration of the study. 3. Parent reports active concern/challenge in behavior and selective eating confirmed by minimum threshold scores on three screening instruments: a. Selective Eating: \