The gut–brain link, explained without the hype

The gut and brain communicate constantly through nerves, hormones and immune signals. Children with digestive discomfort often sleep worse and regulate emotions less easily, and easing the discomfort tends to help both.

That is a meaningful, modest claim. It is not the same as the idea that changing a child's diet will change who they are, and we would be careful with anyone who promises that.

Fibre and fermented foods are the useful levers. Introduce them in very small amounts — a teaspoon of yoghurt, a slightly higher-fibre version of an accepted bread — and hold each step for a week or two before the next.

Go slowly. A large, sudden increase in fibre causes bloating and discomfort, which teaches your child that the new food was a bad idea.