Low Vitamin D Levels and Early Menstruation Linked
Early menstruation, which is a risk factor for psychosocial and behavioral problems in teens and diseases such as breast cancer in later life, appears to be linked to low levels of vitamin D. The study’s results could have important implications for young girls around the world.
The age of first menstruation has been declining
In 1901, a report at the proceedings of the 26th meeting of the American Gynecological Society reported that the mean age of first menstruation (menarche) for girls in the United States and Canada was 13.9 or 14 years. Subsequent research reported that the age of menarche has declined to 12.5 years between 1965 and 1985.
According to one of the authors of the new study, Eduardo Villamor, associate professor in the University of Michigan School of Public Health, the age of menarche has been undergoing a slow decline worldwide for years. He suggests there is an environmental cause behind the decline, because the genetics of puberty have not changed.
One of those environmental causes may be low levels of vitamin D. To investigate this idea, a research team measured the blood levels of vitamin D in 242 girls ages 5 to 12 from Bogota, Colombia. All the girls were followed for 30 months.
The investigators found that 57 percent of girls who had low vitamin D levels started menstruation during the study period compared with 23 percent of girls who had sufficient vitamin D levels. Girls who had low vitamin D levels started menarche at about 11.8 years of age, while girls with sufficient vitamin D levels started menstruation at about 12.6 years of age.
Villamor noted that researchers know little about environmental triggers for puberty. “If we learn what is causing the decline in age of first menstruation,” he said, “we may be able to develop interventions” to prevent girls from experiencing premature menarche.
In another recent study, published in Environmental Research, investigators in Taiwan found that women who were exposed to environmental toxins such as polychlorinated biphenyls (PCBs) at age 5 to 9 years started menarche “slightly earlier with borderline significance.” In Reproductive Toxicology, researchers reported they found an association between exposure to DES and early menarche.
The study by Villamor and colleagues is important because it points out a possible link between low vitamin D levels and early menstruation, although it did not establish insufficient vitamin D as a cause of premature menarche. Additional studies are needed to determine if changing girls’ vitamin D levels will cause a change in age of menarche.
Hatch EE et al. Reproductive Toxicology 2011 Feb; 31(2): 151-57
Medical News 1901 Jun 22; from the proceedings of the 26th meeting of the American Gynecological Society, May 30-June 1, 1901
University of Michigan School of Public Health
Yang CY et al. Environmental Research 2011 Feb; 111(2): 288-94