HEALTH NEWS

Study Title:

Low Vitamin D and First Menstration

Study Abstract

Background: Early menarche is a risk factor for cardiometabolic disease and cancer. Latitude, which influences sun exposure, is inversely related to age at menarche. This association might be related to vitamin D, but to our knowledge it has not been investigated in prospective epidemiologic studies.

Objective: We studied the association between vitamin D status and the occurrence of menarche in a prospective study in girls from Bogota, Colombia.

Design: We measured plasma 25-hydroxyvitamin D [25(OH)D] concentrations in a random sample of 242 girls (mean ± SD age: 8.8 ± 1.6 y) and followed them for a median of 30 mo. Girls were asked periodically about the occurrence and date of menarche. Baseline 25(OH)D concentrations were categorized as <50 nmol/L (deficient), ≥50 and <75 nmol/L, or ≥75 nmol/L (sufficient). The incidence of menarche was compared between groups by using time-to-event analyses.

Results: A total of 57% of girls in the vitamin D–deficient group reached menarche during follow-up compared with 23% of girls in the vitamin D–sufficient group (P-trend = 0.0004). The estimated mean (±SE) ages at menarche in the same groups were 11.8 ± 0.2 y and 12.6 ± 0.2 y, respectively (P = 0.0009). After adjustment for baseline age and BMI-for-age z score in a Cox proportional hazards model, the probability of menarche was twice as high in vitamin D–deficient girls than in girls who were vitamin D–sufficient (HR: 2.05; 95% CI: 1.03, 4.07; P = 0.04). Similar results were obtained in girls aged ≥9 y at baseline (HR: 2.39; 95% CI: 1.14, 5.00; P = 0.02).

Conclusion: Vitamin D deficiency is associated with earlier menarche.

From press release:

A study links low vitamin D in young girls with early menstruation, which is a risk factor for a host of health problems for teen girls as well as women later in life.

Researchers from the University of Michigan School of Public Health measured the blood vitamin D levels in 242 girls ages 5-12 from Bogota, Colombia, and followed them for 30 months. Girls low on vitamin D were twice as likely to start menstruation during the study than those with sufficient vitamin D, said epidemiologist Eduardo Villamor, associate professor in the U-M SPH.

This is important for several reasons, Villamor said. Worldwide, there has been a slow decline in the age of the first menstruation, or menarche, for years, which Villamor says suggests an environmental cause, since the genetics that trigger puberty haven't changed.

"We know relatively little about what triggers puberty from an environmental perspective," Villamor said. "If we learn what is causing the decline in age of first menstruation, we may be able to develop interventions" to prevent premature menarche.

Early menstruation is a risk factor for behavioral and psychosocial problems in teens. Also, girls who have an earlier menarche appear to have increased risk of developing cardiometabolic diseases and cancer -- particularly breast cancer, as adults.

This study formally explored the link between vitamin D status of girls and the time of their first menstruation. Previous research has suggested that menarche happens later in girls living closer to the Equator than girls living in northern countries. Coincidentally, girls in northern countries may harbor high rates of vitamin D deficiencyduring winter months because of limited sun exposure.

In the research by Villamor and colleagues, 57 percent of the girls in the vitamin D-deficient group reached menarche during the study, compared to 23 percent in the vitamin D-sufficient group. In terms of age, girls who were low in vitamin D were about 11.8 years old when they started menstruating, compared to the other group at about age 12.6 years old. This 10-month difference is substantial, Villamor said, because even though 10 months may not seem like a long time, at that age a lot is happening rapidly to a young girl's body.

Still, while the results suggest a link between vitamin D and menarche, they have not established a causal relationship. It's necessary to do more studies to show if interventions that change girls' vitamin D status result in a change in their age of menarche.

Study Information

E. Villamor, C. Marin, M. Mora-Plazas, A. Baylin.
Vitamin D deficiency and age at menarche: a prospective study.
American Journal of Clinical Nutrition
2011 August
Departments of Environmental Health Sciences and Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI.