This review examines how β-glucan, a natural fiber found in mushrooms, yeast, and grains, can help strengthen children’s immune systems and improve their health. Studies show that β-glucan supplementation may reduce the frequency and severity of colds and respiratory infections, improve digestive health, help control blood sugar levels, and support overall development. The evidence suggests that β-glucan could be a valuable dietary supplement for malnourished or immunocompromised children worldwide.