The study published in the online version of the medical journal was led by Mary Penny from the Instituto de Investigacion Nutricional, Lima, Peru.
She and her colleagues set out to test whether a nutritional education programme delivered by government health centres could improve the growth of children in a shanty town in Trujillo, Peru.
The researchers selected six centres at random and introduced a system that ensured that all young children seen in them received appropriate nutrition advice every time they visited.
Nearly 400 mothers were enrolled into the trial from August 1999 to February 2000 - half were from the catchment area of the intervention centres and half from the centres not following the programme.
In order to assess the efficacy of the nutrition advice, field workers visited the families as soon as possible after birth and at regular intervals up to the 18 months of age to assess growth, feeding practices and dietary intake of energy, minerals and vitamins.
They reported that at six months more children in the intervention group were fed nutrient-dense thick foods at lunch (a recommended feeding practice) and met dietary requirements for energy, iron, zinc than controls. The investigators found that the rate of stunting fell by more than two thirds in children of families in the intervention group.
Dr Penny said: "Malnutrition is a major cause of child morbidity and mortality, and effective interventions are urgently needed to prevent growth faltering in young children. Our educational intervention prevented stunting, a form of chronic malnutrition that occurs in more than 15 per cent of infants in this population."
She added that research is now needed "to determine the sustainability of the intervention in Trujillo, and the generalisability of the intervention strategy to similar settings in Peru and elsewhere."
Malnutrition is estimated to cause half of all preventable deaths in infants worldwide. Some of the most common nutritional problems in developing countries are stunted growth and iron-deficiency anaemia.