Children who eat fast food may have poorer academic skills, a study has found.

The consumption of fast food has already been linked to a number of health problems in children, including an increased risk of obesity, but US researchers wanted to investigate whether this type of food also affects how children perform in school.

They assessed the reading, maths and science skills of over 8,500 children who were aged between 10 and 11. All of the children also filled out a questionnaire on their food consumption.

This questionnaire revealed that at least two in three of the children had consumed some type of fast food in the previous week, with one in five of these consuming at least four fast food meals during this time.

One in 10 was found to have consumed fast food every day during the previous week.

The children's reading, maths and science skills were then reassessed three years later, when they were 13 or 14 years of age.

The researchers found that those who ate higher amounts of fast food when they were 10 or 11, had poorer levels of academic achievement than their peers who consumed less or no fast food.

In fact, those who ate fast food four to six times per week when they were 10 or 11 scored up to 20% lower in reading, maths and science tests when they were 13 or 14 years of age, compared to children who did not eat fast food.

Even children who only consumed between one and three portions of fast food per week when they were 10 or 11 scored lower in maths by the time they were 13 or 14.

The researchers from Ohio State University and the University of Texas said that the results stood even after other factors were taken into account, such as socioeconomic status and time spent watching television.

"These results provide initial evidence that high levels of fast food consumption are predictive of slower growth in academic skills," the researchers concluded.

They added that parents should limit fast food consumption among children as much as possible.

Details of these findings are published in the journal, Clinical Pediatrics.