New York: Girls who frequently consume sugary drinks tend to start their menstrual periods earlier than girls who do not, new research shows.

The team from the Harvard Medical School in the US looked at the relation between sugar-sweetened drinks and the age at which girls have their first period.

They followed 5,583 girls, aged 9-14 years between 1996 and 2001 and found that those who drank more than 1.5 servings of sugary drinks a day had their first period 2.7 months earlier than those who consumed two or fewer such drinks a week.

"The main concern is about childhood obesity but our study suggests that age of first menstruation occurred earlier, independently of body mass index, among girls with the highest consumption of drinks sweetened with added sugar," said Karin Michels, associate professor, who led the research.

Drinks with added sugar have a higher glycemic index than naturally sweetened drinks such as fruit juices.

High-glycemic foods result in a rapid increase in insulin concentrations in the body.

Higher insulin concentrations can result in higher concentrations of sex hormones and large alterations in the concentrations of these hormones circulating in the body has been linked to periods starting earlier.

Greater caffeine intake has also been associated with earlier periods.

"Our findings provide further support for public health efforts to reduce the consumption of sugary drinks," Michels added.

The findings are important not only because of the growing problem of childhood obesity in a number of developed countries, but also because starting periods earlier is linked to an increased risk of breast cancer later in life.

The research was published online in the journal Human Reproduction.