The first three years for a child are seen as the most important, as it is the foundation upon which learning, behavior, health, and wellbeing are built upon later in life. By the time a kid reaches 3 years old, 80% of their brain has already been developed. During these years, neutral connections or neural circuits are established, then after 4 years the brain changes. A toddler's organs, bones, and muscles also develop at a far more intense and rapid rate than older children, which is why in addition to the basic vitamins, it is essential they are getting enough calcium, iron and Vitamin D. These three nutrients are especially important during this phase of physical and cognitive growth.