If your daughter is eating a well-balanced diet and does not have any vitamin deficiencies, there may not be clear benefits to giving her vitamins as a preventive measure against colds and stomach bugs. However, probiotics could potentially help improve her gut health and potentially help her fight off infections. It is important to not overdose on certain vitamins and to focus on good hygiene practices to prevent infections. Consulting with a pharmacist can help you choose the right supplements for your daughter if you are interested.