Girls who consume lots of sugary drinks start menstruating at a younger age, according to a study published in the journal Human Reproduction. The study findings are important because early onset of menstruation has been linked to a higher risk of breast cancer in later life.
Researchers monitored the health of more than 5,500 American girls aged 9 to 14 years between 1996 and 2001. The average age for onset of menstruation was 12 years and 7 months. The investigators found that during the study period, girls who drank between one-and-a-half servings of sweetened drinks per day had their first period 2.7 months earlier than those who had two or fewer sweet drinks a week. The earlier menstruation occurred regardless of the girls' height-to-weight ratio, their body mass index (BMI), their total calorie intake and exercise regime.
A 2.7-month earlier onset translates into a modest impact on breast cancer risk as previous work had found that starting menstruating one year earlier increases the cancer risk by about 5 percent. Karin Michels of Harvard Medical School, who led the probe, said, "Our study adds to increasing concern about the widespread consumption of sugar-sweetened drinks in the USA and elsewhere."
This study was based on statistics, and was not powered to explore the causes. The authors point to previous research that says high, swift doses of sugar causes a rapid increase in levels of the hormone insulin, which in turn has a knock-on effect on concentrations of sex hormones.
However, some experts were cautious of the findings, pointing in particular at the source of the data and terming the reference to breast cancer as overly alarmist.