According to a new study in the Netherlands, children, who are severely obese, put their heart at the danger even when they are still in primary school.

Researchers at the VU University Medical Centre in Amsterdam say that even as heart problems are common in middle aged people, they detected early warning signs in severely obese children between the ages of 2 and 12. They said that about two-thirds of the 307 children studied in the research showed one early symptom such as high blood pressure.

A Body Mass Index, which a measure of obesity, of more than 20.5 for two year old children is considered severely obese. For 18 year olds, an index of more than 35 shows severe obesity. The researchers studied data from the Dutch Paediatric Surveillance Unit between 2005 and 2007 and looked at warning signs of heart disease in the severely obese children.

"Remarkably, 62% of severely obese children under 12 years of age already had one or more cardiovascular risk factors," the researchers said.

The findings of the study were presented in Archives of Disease in Childhood.