The vitamin supplement aisle is overwhelming. There are gummies and drops and chewables and sprays. There are supplements for everything from brain development to immune support to digestive health. As a parent you can spend a fortune on things your toddler may not need at all. So let me give you the honest picture. The evidence-based supplements for toddlers are actually quite modest. Vitamin D is the one supplement most health authorities in northern latitudes genuinely recommend for all toddlers regardless of diet. In the UK the NHS recommends 10 micrograms daily for children aged 1 to 4. In the US the AAP recommends 600 IU per day. The reason is simple: vitamin D is primarily made by sunlight on skin and in northern climates there is insufficient sunlight for much of the year. Omega 3 DHA is worth considering for toddlers who do not eat oily fish regularly. DHA supports brain and eye development. An algae-based supplement is suitable for all diets. Iron supplementation is only recommended if a blood test shows deficiency. Do not supplement iron without medical guidance as too much iron is harmful. Vitamin C is not necessary as a supplement for toddlers eating any fruit or vegetables. Probiotics have some evidence for specific situations like after antibiotic use but are not universally recommended. Most other supplements marketed for toddlers have limited evidence. A varied diet including some animal products, fruit, vegetables, and dairy covers the vast majority of nutritional needs. If your toddler has dietary restrictions or very limited food variety, discuss specific supplementation with your pediatrician or a registered dietitian rather than guessing.