Girls who grow up eating a healthier diet than their peers may be less likely to get their first menstrual periods at an earlier age — regardless of height or body mass index — a new study suggests.
Though previous research has tied height and BMI to the earlier onset of menarche, or first period, the study, published Tuesday in the journal Human Reproduction, claims to be the first to explore the biological milestone’s link to specific diets.
Girls typically begin puberty — marked by acne, growth spurts, breast development and the growth of body and pubic hair — anywhere from ages 8 to 13, according to the Eunice Kennedy Shriver National Institute of Child Health and Human Development. They get their first periods roughly two years after their breasts start developing.
While precocious puberty, which is the onset of puberty in girls younger than 8 and boys younger than 9, affects just 1% of U.S. children, girls nationwide are getting their first periods earlier and earlier. The median age at menarche was 11.9 in 2013 through 2017, down from 12.1 in 1995, according to the National Center for Health Statistics.
Early menarche is more than untimely sexual maturity. Girls who get their periods younger than average are at increased risk of myriad medical problems throughout adolescence, such as depression, substance abuse and eating disorders. As adults, they have heightened odds of developing breast cancer, heart disease, obesity and other conditions.
To study the possible effects of diet on the age of a girl’s first period, researchers at the Fred Hutchinson Cancer Center in Seattle looked at the health records of more than 7,500 children ages 9 to 14 who had been enrolled in two waves of the Growing Up Today Study, from 1996 through 2001 and 2004 through 2008. As part of that study, the kids completed questionnaires about the foods they ate.
The researchers used two scales to gauge the girls’ self-reported eating habits. One looked at how healthy a child’s diet was, giving more points for healthier foods, such as legumes, whole grains and vegetables, and deducting points for less healthy foods, including red meat and products high in salt and trans fats. The second scale looked at how much people’s diets contributed to inflammation, with foods such as refined grains, high-calorie drinks and red and processed meat considered more inflammatory.
The median age of participants’ first periods was 13.1, the study found.
Girls who ate healthiest, the study estimated, were more likely to get their periods at a slightly older age than those who reported eating the least healthy diets. Similarly, girls who ate the highest amounts of inflammatory foods were more likely than those who ate the lowest amounts to get their first periods at a slightly younger age.
The study is observational, meaning it doesn’t prove that a particular diet causes early periods but instead establishes a possible link. A major limitation of the study is that the majority of participants were white. Race and ethnicity are well-studied aspects of early menarche, with Black and Hispanic girls more likely to experience it.
What should girls eat to avoid early periods?
One hypothesis linking diet and age of first period, the authors wrote, is that the foods a person eats can affect levels of sex hormones in the body. A previous study of premenopausal women found that eating a healthier diet is linked to lower levels of certain sex hormones, including versions of estrogen. Inflammation has also been shown to have an effect on sex hormone levels.
Previous research has shown that excess fat, or adipose tissue, influences the hormone pathways that regulate puberty, said Erin Hennessy, director of the ChildObesity180 program at Tufts University, who wasn’t part of the study.
“Adipose tissue produces certain hormones, including leptin, which send signals to the brain, and the thought is that higher levels of leptin among children with excess weight can trigger specific hormones that initiate puberty earlier,” Hennessy said in an email. “Adipose tissue can also alter sex hormones, leading to higher estrogen levels that promote breast development and menarche onset.”
Diet alone doesn’t determine the timing of a girl’s first period. Genetics, environmental toxins, physical activity and socioeconomic status, among other factors, also play roles. Still, parents can support their children’s overall health and well-being through nutrition, Hennessy said.
“The first strategy is to acknowledge that weight is one of many factors of health and should never be the sole focus,” Hennessy said. “The second strategy is to take a family approach — everyone in the family can benefit from healthy eating.”
Third, Hennessy encourages parents to provide nutritional structure that isn’t coercive or overly controlling, such as pressuring children to eat or using food as a reward. Parental role modeling is a simple way to guide food choices and help children build healthy eating routines. Parents might also consider engaging their children in meal planning and preparation.
When in doubt, Hennessy said, refer to the Agriculture Department’s MyPlate program for dietary recommendations for children at different developmental stages.
“Emphasis should be on the major food groups and include a variety of foods within each group,” Hennessy said. Your meals should include “a rainbow of fruits and vegetables; at least half of your grains are whole grains; lean proteins (meat, fish, poultry, eggs, beans and nuts) and low-fat dairy or dairy alternatives.”
In addition, the Dietary Guidelines for Americans encourage limiting intake of sodium, added sugars and saturated fats.
“No matter what your weight status, a healthy diet is important for better health,” Hennessy said.
Even for preteens who’ve long consumed unhealthy foods, puberty presents an opportunity for positive change, said Dr. Rachel Whooten, a pediatric endocrinologist at Massachusetts General Hospital for Children, who wasn’t involved in the study.
It’s “a key time to optimize all of the health behaviors — optimize nutrition, optimize physical activity, optimize sleep, decrease screen time,” Whooten said. “A lot of those behaviors do worsen throughout middle and later adolescence. … It’s never too late to promote the healthier habits.”