Nearly one in six children and teenagers who started taking GLP-1 medications developed a new nutritional deficiency within a year, according to a study published last week, raising concerns that doctors may not be doing enough to monitor the nutritional health of young patients prescribed these increasingly popular drugs.

Researchers at Northwestern University’s Feinberg School of Medicine, along with collaborators at other institutions, examined medical claims data from a large database of real-world patients, identifying roughly 2,000 children between the ages of 10 and 17 who began taking a GLP-1 medication between 2017 and 2022 and had no preexisting nutritional deficiency noted in their medical records at the time. Within a year of starting the medication, about 17% of these children were diagnosed with either a nutritional deficiency or a related complication, such as anemia. Vitamin D deficiency was the most common diagnosis, identified in 12% of the children studied, followed by nutritional anemia at 1.55% and iron-deficiency anemia at 1.44%. The findings were published in the journal Childhood Obesity.

“Nutritional deficiencies are a meaningful and underrecognized risk among pediatric patients receiving GLP-1RA therapy,” the study’s authors wrote in their paper.

GLP-1 medications, including semaglutide, sold under the brand names Ozempic and Wegovy, and tirzepatide, sold as Mounjaro and Zepbound, have emerged in recent years as effective treatments for obesity and type 2 diabetes, including in pediatric patients. Childhood obesity remains a significant public health concern in the United States, with the Centers for Disease Control and Prevention’s most recent data showing approximately 22% of adolescents ages 12 to 19 classified as obese, along with 21% of children ages 6 to 11. Despite the drugs’ growing use among younger patients, researchers say considerable uncertainty remains about their long-term effects specifically in children.

The study’s design means its findings carry important limitations. Because the research was observational rather than a controlled clinical trial, the researchers cannot conclusively establish that GLP-1 use directly caused the nutritional deficiencies identified in the study, only that the two were associated within the studied population. The data also covers a period predating the more widespread adoption of GLP-1 medications for pediatric patients in more recent years, meaning current prescribing and monitoring practices may differ from those reflected in the dataset.

Even accounting for those limitations, the researchers noted that their findings align with a broader body of existing research. Intentional weight loss generally, regardless of the method used to achieve it, has previously been shown to increase a person’s risk of developing nutritional deficiencies. Other recent studies have similarly identified links between GLP-1 medication use and nutrition-related health problems, including rare but serious conditions tied to specific nutrient deficiencies.

While the study could not definitively explain why the children in the dataset developed these deficiencies, the researchers pointed to apparent gaps in the nutritional counseling many of the young patients received after starting their medication. According to the study, only about 5% of the children in the dataset received dietary counseling within the first 30 days after being prescribed a GLP-1 medication, and only a quarter received such counseling within six months of starting treatment.

Study author Justin Ryder, an associate professor of surgery and pediatrics at Northwestern University and a surgeon at the Ann & Robert H. Lurie Children’s Hospital of Chicago, said the findings point to a need for more proactive nutritional management rather than a reactive approach that waits until a deficiency has already developed. “We hope that our study findings bring much-needed recognition to the importance of proactive nutritional management when GLP-1s are prescribed to children, as opposed to waiting until a nutritional deficiency is diagnosed,” Ryder said in a statement released by the hospital. “Knowing the risks, we are in a much better position to prevent harm to children treated with GLP-1s during a pivotal period in their lives.”

The American Academy of Pediatrics began recommending GLP-1 therapy as a treatment option for childhood obesity in 2023. Those same recommendations emphasized the importance of pairing any pharmacological treatment with nutritional support for young patients, guidance that appears, according to the new study’s findings, to not always be consistently followed in real-world clinical practice.

The new findings add to a growing body of research examining both the benefits and potential risks associated with GLP-1 medications across different patient populations. Separate recent studies have identified other effects tied to the drugs, including associations between GLP-1 use and reduced rates of certain serious infections, as well as effects on respiratory conditions such as asthma and chronic obstructive pulmonary disease linked to the medications’ impact on obesity-related disease risk.

With GLP-1 prescriptions continuing to expand among pediatric patients treating obesity and type 2 diabetes, the study’s authors say their findings underscore the importance of consistent nutritional monitoring throughout a child’s course of treatment, rather than relying on providers to identify deficiencies only after symptoms or complications have already emerged. Given the observational nature of the current research, further studies, including those examining more recent prescribing patterns and monitoring practices, are likely needed to more precisely determine how significant a risk nutritional deficiencies pose to the growing population of children and teenagers using these medications.