Growing adolescents need a diet rich in iron, according to Hans-Juergen Nentwich, an executive board member of Germany’s Professional Association of Children’s and Young People’s Physicians. “Pale skin, fatigue, a poor appetite, brittle fingernails and hair, cracked skin in the corners of the mouth and chapped lips can be signs of a deficiency,” he warned.

Various metabolic processes in the body depend on iron, which is important for blood formation and oxygen supply to the organs. In boys, muscle mass and blood volume increase greatly in a short period of time. Girls lose iron during menstruation.

“A children’s and young people’s physician can detect an iron deficiency with a blood test,” Nentwich said. “A dietary change and, if needed, dietary supplements can them help to restore the body’s iron reserves.” Foods containing iron include meat, leafy green vegetables, red beets, garden cress, fish, eggs, whole grain products, legumes and nuts.

“An iron deficiency also makes people more susceptible to infections,” noted Nentwich, who said it could impair brain function as well. According to a study, an iron deficiency in one’s teen years could negatively affect brain structure in the long term. A deficiency impairs formation of myelin, an electrically insulating material that sheathes nerve fibres and increases the speed of impulses between nerve cells in the brain.