Your Toddler’s Busy Brain

There is massive brain development during your toddler’s first three years. This development has long-term impact. Alf Nicholson, RCSI Professor of Paediatrics at Temple Street Children’s University Hospital, and Toddlebox development expert, explains how important caring relationships and nutrition are to your growing toddler!


In the last 30 years, we have learned more than ever before about the inner lives of babies and toddlers. More brain development happens in the first three years than we knew. Your toddler’s brain development is extensive and easily affected by the world around them. What happens in these early years has a long-term impact. Evidence shows that early relationships and parental care have a very important part in brain development. They affect social, emotional and learning development. They may even affect your toddler’s lifelong health.

Your toddler could have 900 words by age three! And their brain is 80-90% of its adult size!

A synapse is the place where a signal passes from one nerve cell in the brain to another. This is how the brain builds and connects. During your toddler’s first few years, between 700 and 1000 new connections are formed every second! This is faster than at any other time.


  • These years are a unique time for brain development, so getting nutrition right is very important.
  • Because this is a time of such rapid growth, toddlers are at particular risk of iron deficiency. A lack of iron can cause anaemia; a lack of red blood cells in the body.
  • Toddlers need lots of iron because it supports this incredible burst of brain growth. They need to get 8mg/day in their diet daily.
  • Iron deficiency does not just make your toddler pale and a bit miserable, but if severe can cause a delay in brain development. It is important to know which foods are rich in iron and to encourage your toddler to eat them as much as possible.

Unfortunately, iron deficiency is common in the toddler age group: up to 10% of toddlers are iron–deficient. This generally relates to their diet. It is reasonable to recommend up to 300mls of an iron-fortified or growing up milk as part of a healthy balanced diet.


During the first three years, our long-term ability to think, understand, trust, and care about others is shaped. Experiences such as a child’s relationship with their parents (and family) and caregivers shape brain development. The strength and quality of these relationships is key to the effective development of brain functions and capacity. This means that the first three years of life, while the brain is growing rapidly, are critical to long-term outcomes.

Early experiences can affect your toddler’s potential. Early experiences provide either a strong or a fragile platform for their future development and learning. Research shows that the greatest opportunity to set up your child’s ideal development is during these early years.

Positive relationships help young children to develop self-confidence and sound mental health. They provide the motivation to learn and to achieve, an understanding of the difference between right and wrong. They affect toddlers’ capacity to develop and sustain relationships, and, ultimately, the ability to be successful parents themselves.

Meeting your toddler’s developmental needs is more than getting them ready to succeed in school. It’s about building a strong foundation for lifelong physical and mental health.

All the adults in your toddler’s life – parents, grandparents and childcare providers – have a responsibility to help them develop to their full potential.

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