When my son started nursery at 2 years old he caught approximately every illness that existed within a 10-mile radius. Colds, stomach bugs, hand foot and mouth, croup. I was cleaning surfaces, giving him vitamins, and wondering what I was doing wrong. Here is what the paediatrician told me: children at nursery get 8 to 12 respiratory illnesses per year on average. That is normal. That is their immune system learning. Being frequently ill in the early years actually builds immune resilience for later life. That said, there are things that genuinely support immune function in toddlers and things that are largely marketing. What actually works: sleep is the most powerful immune support available. During sleep, the body produces and releases cytokines which fight infection. Toddlers need 11 to 14 hours of sleep per day. Nutrition: a varied diet rich in fruit, vegetables, protein, and whole grains provides the micronutrients the immune system needs. There is no single superfood. Variety is the key. Vitamin D supplementation as recommended by your health authority since deficiency is genuinely linked to increased infection susceptibility. Physical activity: regular outdoor play and movement supports immune function. Reducing unnecessary antibiotic use: antibiotics disrupt the gut microbiome which plays a significant role in immune regulation. Only use them when genuinely necessary and prescribed. Hand washing: simple, boring, and one of the most evidence-based infection prevention tools available. What does not have strong evidence: most immune support supplements marketed for children, echinacea, elderberry, and probiotic supplements for general immune boosting in healthy children.