Young girls who consume a lot of sugary drinks tend to begin menstruating earlier, a new study has found.

This marks the first study to investigate a link between these drinks and the age at which a girl gets her first period. It involved over 5,500 girls aged between nine and 14, who were monitored over a five-year period.

At the beginning of the study, none of the girls had begun menstruating, but by the end of it, all but 3% had begun.

It found that girls who consumed more than 1.5 servings of sugary drinks every day began menstruating over two-and-a-half months earlier than girls who consumed two or less servings per week. A serving was counted as one can or glass of the drink.

These results stood even when other factors were taken into account, such as the girl's body mass index (BMI) and physical activity levels.

The researchers from Harvard Medical School in the US said that the findings are important because earlier menstruation has been linked to an increased risk of developing breast cancer later in life.

According to lead researcher, Dr Karin Michels, these findings ‘add to increasing concern about the widespread consumption of sugar-sweetened drinks among children and adolescents'.

"The main concern is about childhood obesity, but our study suggests that age of first menstruation occurred earlier, independently of BMI, among girls with the highest consumption of drinks sweetened with added sugar. These findings are important in the context of earlier puberty onset among girls, which has been observed in developed countries and for which the reason is largely unknown," she noted.

All of the girls were asked about their diet, including their consumption of sugar-sweetened beverages, such as cola and lemonade. However, they were also asked about their consumption of diet fizzy drinks and fruit juice, in order to investigate the impact of artificially and naturally sweetened drinks.

The study found that diet fizzy drinks and fruit juices did not affect the age at which the girls began menstruating.

The researchers pointed out that sugary drinks have a higher glycaemic index than naturally sweetened drinks such as fruit juice, and this can result in a more rapid increase in the body's concentrations of insulin. Higher concentrations of insulin can lead to higher concentrations of sex hormones and big changes in these concentrations have been linked with earlier menstruation.

The researchers also noted that while previous studies have suggested a possible link between caffeine consumption and earlier menstruation, their study found that caffeine intake and total sugar did not explain their results - it was the added sugar found in the sugar-sweetened beverages that was to blame.

"Our findings suggest that frequent consumption of sugar-sweetened beverages may be associated with earlier menarche (menstruation) and provide further support for public health efforts to reduce the consumption of sugary drinks," Prof Michels said.

She added that the public health significance of these findings ‘should not be overlooked, since unlike most other predictors of menstruation, sugar-sweetened beverage consumption can be modified'.

Details of these findings are published in the journal, Human Reproduction.