Several features and comorbidities in Down syndrome have nutritional implications and consequences. In infancy and early childhood, children with Down syndrome have a high risk of oral motor difficulties and pharyngeal dysphagia with aspiration, which both require systematic attention. To improve nutritional status in children who are underweight and who have clinical signs of feeding problems, further evaluation of underlying causes is required. Clinical interventions should promote swallowing safety and development of feeding abilities. Even from 4–5 years of age, overweight in children with Down syndrome can be a concern. To prevent disease later in life, an urgent need exists for more research on nutritional aspects in the prevention and treatment of obesity in adolescents with Down syndrome. This Review did not find any data to support the use of dietary supplementation, except when deficiency is documented. Additionally, the literature reported the need for more research that uses larger study samples and control groups and that addresses important nutritional challenges in children and adolescents with Down syndrome.