The children, aged from 13 to 16, were given Wellteen supplements, produced by Vitabiotics, or a placebo. Levels of vitamins, minerals and omega-3 in the blood were measured throughout the trial, and their behaviour was measured in tests and from school disciplinary records.

The behaviour of the students given the supplements improved dramatically during the three months, while that of the placebo group worsened, say the researchers.

The children all attend the Robert Clack secondary school.

The supplements, which include 25 nutrients such as cranberry and green tea extracts, iron, zinc and vitamins C, B6 and B12, are designed to improve mood, behaviour, and brain function.