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Health & Wellness

One more possible reason girls are having early periods: sugary drinks

Aside from those cavities and pound-packing calories, here’s another reason young girls may want to put down those sugar-sweetened beverages.

Researchers are finding girls who frequently imbibe drinks laden with added sugar tend to start their periods earlier than girls who don’t overindulge, according to research published online Tuesday in the journal Human Reproduction. And girls may not only be ruining their teeth and their waistlines. They may be putting themselves at slightly greater risk of breast cancer during their lifetimes.

In the study, researchers wanted to look at the relationship between sugar-sweetened drinks, such as regular soda, sweetened ice tea, and non-carbonated offerings like lemonade or fruit punch, and the age at which girls started their first period.

What the researchers found is that those girls who drank more than 1.5 servings of sugary drinks every day had their first period 2.7 months earlier than those who consumed two or fewer such drinks a week. One limitation of these findings is that the survey didn’t specify how many ounces in a serving, which in the U.S. can vary drastically from standard 8 ounces up to 20 ounces. 

This effect was independent of the body mass index (BMI) of the girls, height, total food intake and other lifestyle factors such as physical activity.

Among the 5,583 girls, ages 9 to 14 who participated in the study between the years 1996 and 2001, those who consumed the most sugary drinks started menstruating at 12.8 years of age, compared to 13 years for those drinking the least. Study participants were part of the Growing up Today Study, which follows 16,875 children of Nurses’ Health Study II participants.The researchers also investigated diet sodas and fruit juice to assess the impact of artificially or naturally sweetened drinks, and found they were not associated with any difference in the age at which girls started their periods

Although a 2.7 month difference in age of menarche is not a huge effect on an individual level, it is important on a population level, says Harvard School of Public Health epidemiologist Dr. Jenny Carwile, the study’s lead author. “They (the findings) are actually very powerful because consumption of these kinds of drinks is something that can be modified,” she says.

Brent Hofacker / Today
Those who consumed the most sugary drinks, including sodas, started menstruating at 12.8 years of age, compared to age 13 for girls who drank the least.

Beverages that contain added sugar have a higher glycemic index than naturally sweetened drinks such as fruit juices. The glycemic index is a number that is associated with how certain foods affect blood sugar levels, and these so-called high glycemic foods result in rapid increases 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, say researchers.

Studies do show that a one-year decrease in age at menarche is estimated to increase the risk of breast cancer by only 5 percent, and a 2.7 month decrease will undoubtedly have a more modest impact, if any. 

“This is a small, but statistically significant finding,” says reproductive endocrinologist Dr. James Liu, chairman of obstetrics and gynecology at University Hospitals Case Medical Center in Cleveland, Ohio. “Whether this can be linked to anything long term is still speculation, and more people need to look at it.”

Nonetheless, “. . . sugary drinks and the metabolic effects they have are very interesting and potentially important in terms of cancer risk,” says breast surgical oncologist Dr. Katherine Kopkash of Rush University Medical Center in Chicago, Illinois.

Doctors do know that maintaining a healthy body weight and getting exercise reduces risk of breast and other cancers. 

“But we all know people who may have great body mass indexes, but are still prone to metabolic issues,” Kopkash says. “Decreasing sugary beverage consumption is just one more thing you can do to help yourself potentially reduce your risk of cancer. So I would tell a group of young girls to watch that sugar.” 

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