Concentrations of vitamin D in children and adolescents in Brazil

Posted February 4, 2025

What is the concentration of vitamin D and risk factors for its deficiency among children and adolescents in Brazil? Knowing these data was the main objective of the study “Alert for the high prevalence of vitamin D deficiency in adolescents in a large Brazilian sample.” The article is part of the doctoral thesis by Dra. Vanessa Radonski, supervised by the coordinator of INCT Hormona at Universidade Federal de São Paulo (UNIFESP), Dra. Marise Lazaretti Castro, through the UNIFESP Graduate Program, and had great repercussion: the article was the theme of an editorial published in Jornal de Pediatria, calling the attention of the scientific community.

The group evaluated more than 410 thousand measurements in children and adolescents aged zero to 18 years, obtained from the database of clinical laboratory, covering all Brazilian regions. The results were distributed by gender, age group, seasonality, and latitude. The study is available at the following link: https://pubmed.ncbi.nlm.nih.gov/38462231/

According to Dr. Castro, the study made it possible to obtain a good picture of concentrations of 25 hydroxyvitamin D [25(OH)D] in this population. “One of the surprises of this work was that we observed that, although severe vitamin D deficiency [25(OH)D < 10 ng/mL], is rarer in Brazil, it reached 5% of measurements during the winter months in cities with greater,” she states.

The doctor also comments that concentrations < 20 ng/mL, which are also indicative of vitamin D deficiency for this age group, were found in more than 20% of samples in adolescents aged from 12 to 18 years. “This most probably may be explained by the behavioral changes that occur in this stage of life, with reduced sun exposure, greater involvement in study and work, and also by habits such as spending a longer time in from of screens and little time playing sports and performing outdoor activities, for example,” she explains.

Another point to be highlighted is that both seasonality and geographic location also influence hormone concentration and may be considered risk factors. “Vitamin D concentration is lower in the population in winter and spring, for example, as well as in the cities located more to the south of the country, with an increased risk of deficit,” she warns. According to the article, in samples of female adolescents from the southern region in winter, 36% of vitamin D deficiency and 5% of severe deficiency were found.

Still according to the research, a greater deficiency was observed among adolescents, especially females, which raises questions on the need for supplementation during this period of life. “The article calls physicians’ attention to focus on this age group and to prescribe vitamin D replacement,” she concludes.