Sugary drinks may cause girls to start their periods early

Girls who frequently consume sugary drinks tend to start their menstrual periods earlier, which can put them at an increased risk of developing breast cancer later in life, a new study suggests.
Researchers from Harvard School of Public Health, Boston, and colleagues followed 5,583 girls, aged 9-14 years between 1996 and 2001.
They 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.
This effect was independent of the girls' body mass index (BMI), height, total food intake and other lifestyle factors.

"Our findings suggest that frequent consumption of SSBs [sugar-sweetened beverages] may be associated with earlier menarche," researchers said.
"A one-year decrease in age at menarche is estimated to increase the risk of breast cancer by 5 per cent thus, a 2.7 month-decrease in age at menarche likely has a modest impact on breast cancer risk," researchers said in the study published in the journal Human Reproduction.

"The amount of SSBs consumed by girls in our highest category of consumption, more than 1.5 servings per day, however, is likely low compared with consumption in certain other populations, in which we would expect an even more dramatic decrease in age at menarche.

"Most importantly, the public health significance of SSB consumption at age at menarche, and possibly breast cancer, should not be over-looked, since, unlike most other predictors of menarche, SSB consumption can be modified," they said.
The girls in the study were part of the Growing up Today Study, which follows 16,875 children of Nurses' Health Study II participants living in all 50 states of the US.
Diet sodas and fruit juices were not associated with any difference in the age at which girls started their periods.
However, at any age between nine and 18.5 years, girls who reported consuming more than 1.5 servings of sugar-sweetened drinks a day were, on average, 24 per cent more likely to start their first period in the next month relative to girls consuming two or fewer servings a week.

The average age of the first period among girls consuming the most sugary drinks was 12.8 years, compared to 13 years for those drinking the least.
When the researchers adjusted their results to take account of BMI, the effect of sugary drink consumption on the age of onset of menstruation was still significant: girls consuming the most were 22 per cent more likely to start their first period in the next month compared to girls consuming the least.
The researchers said that drinks with added sugar have a higher glycemic index than naturally sweetened drinks such as fruit juices, and 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.