Girls who frequently consume sugary drinks tend to start their menstrual periods earlier than girls who do not, according to new research published online Jan 28 in Human Reproduction. In the first study to look at the relation between sugar-sweetened drinks and the age at which girls have their first period, researchers followed 5583 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. This effect was independent of the girls' body mass index (BMI), height, total food intake and other lifestyle factors such as physical activity.

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.

Karin Michels (ScD, PhD), Associate Professor at Harvard Medical School (Boston, USA), who led the research, said: "Our study adds to increasing concern about the wide-spread consumption of sugar-sweetened drinks among children and adolescents in the USA and elsewhere. The main concern is about childhood obesity, but our study suggests that age of first menstruation (menarche) occurred earlier, independently of body mass index, 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.

In the paper, the authors conclude: "Our findings suggest that frequent consumption of SSBs [sugar-sweetened beverages] may be associated with earlier menarche. A one-year decrease in age at menarche is estimated to increase the risk of breast cancer by 5%..... thus, a 2.7 month-decrease in age at menarche likely has a modest impact on breast cancer risk. 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."