Malnutrition among children and adolescents in Switzerland

An article published in April's Medical Gazette suggests that certain eating habits are leading to deficiencies that are far more widespread than imagined among children and teenagers in Switzerland. The article reports on the return of scurvy, a disease long associated with sailors who sailed the seas for months at a time between the 16th and early 20th centuries, and who, deprived of fresh fruit and vegetables, ate only canned goods. Iron deficiency is also very common. It can manifest itself in the form of depression, according to this article. There's also the return of iodine deficiency, which can lead to thyroid problems and used to cause mental retardation, better known as cretinism. How can we explain malnutrition in a rich, developed country? What can be done about it?