Fish Oils Fish oils contain healthy fats called omega-3s – also known as essential fats. This is because the body cannot make them and they have to be eaten very regularly in the diet. The chemical structure of these polyunsaturated fats also means they’re very healthy for the body. Their chemical structure contains three double bonds, ensuring these fats provide flexibility for cell membranes; they are an intrinsic part of all our cellular make-up. Omega-3s have also been shown to provide positive effects on children’s brain development, behaviour and intellect.