METALS, MENSES, AND MATURATION: UNVEILING THE ROLE OF DIETARY HEAVY METAL EXPOSURE ON THE ONSET OF MENARCHE: AN NHANES STUDY

Abstract

Background: The timing of menarche is considered a sensitive indicator of overall health and development in girls. Early menarche, defined as the onset of menstruation before the age of 11, has been associated with a higher risk of adverse health outcomes in adulthood, including obesity, metabolic syndrome and certain types of cancer. Conversely, delayed menarche, occurring after the age of 15, has been linked to a higher risk of osteoporosis and reproductive disorders. A potential association between dietary exposure to heavy metals and the timing of menarche has been hypothesized in several studies. Exposure to heavy metals including lead, cadmium and mercury has been associated with various health effects, including endocrine disruption leading to early/delayed menarche. Objectives: To investigate the association between dietary patterns, heavy metal exposure and the timing of menarche in a representative sample of young girls using data from the NHANES database. Methods: A cross-sectional analysis was conducted using data from the NHANES database from 6 continuous survey cycles including girls aged 12-18 years. Statistical analysis was performed to determine the association between exposure to heavy metals rich dietary pattern and the age at menarche. Multivariable regression models were used to adjust for potential confounding factors such as socioeconomic status, body mass index (BMI), physical activity levels and ethnicity. Factor analysis was used to identify dietary patterns. STATA software was used for the analysis, and p values less than 0.05 were considered statistically significant. Results: There was a significant reduction in the odds of early onset of puberty for girls in the third quartile 0.60 (0.43-0.82) of blood lead levels compared to the first quartile. However, the trend p-value in the adjusted model was 0.135, suggesting that the overall linear trend across quartiles was not statistically significant. Restricted cubic spline method used with three knots of Log transformed blood lead shows that there was a significant non-linear association between blood lead and early onset of puberty. The odds of early onset of puberty showed a U-shaped curve. There was no significant association observed across quartiles of cadmium exposure (p = 0.290) and mercury exposure (p=0.987) and early onset of puberty among girls. Two main dietary patterns, the Western pattern and the Prudent patterns were identified by factor analysis. Western pattern demonstrated a significant negative association with mercury levels (β = -0.05(-0.09 to -0.01), p = 0.027). Conversely, the Prudent pattern, exhibited a significant positive association with mercury levels (0.09 (0.04 to 0.14), p <0.001) and a significant negative association with lead levels (β = (-0.06 (-0.09 to -0.03), p < 0.001) indicating that girls adhering to the Prudent pattern may have a protective effect against Lead. A subgroup analyses revealed no significant associations across any strata. Conclusion: This study found that the relationship between lead exposure and puberty onset is not straightforward and may be influenced by various factors, including co-exposure to other environmental toxins, nutritional status, and socioeconomic conditions. Interestingly, dietary patterns showed intriguing associations with heavy metal concentrations that warrant further investigations. No significant association was found between Cadmium and Mercury levels or dietary patterns and the timing of menarche.