Hair Mercury, Serum ω-3 Fatty Acids, and Menstrual Symptoms among Women Seeking Fertility Care

In the general population, fish is the main source of Methylmercury (MeHg) and long-chain omega-3 polyunsaturated fatty acids (n-3PUFAs). MeHg is a neurotoxin and reproductive health disruptor. MeHg exposure has been associated with adverse reproductive and neurologic health outcomes, whereas n-3PUFAs have been demonstrated to be beneficial in attenuating the adverse impact on neurologic and reproductive health outcomes. However, there is limited epidemiologic evidence evaluating joint effects of both exposure biomarkers concurrently on women's reproductive health.

The objective of this study was to evaluate the association between MeHg exposure, menstrual symptoms, and serum n3PUFAs [eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA)].

In this observational cross-sectional study, we evaluated 320 women with measurements of hair Hg (0.06-2.48 ppm), serum n-3PUFAs EPA and DHA, and self-reported menstrual symptoms. Menstrual symptoms included tension/irritability, mood swings/depression, sweats/hot flashes, weight gain/breast or abdominal swelling, and headaches. We used log-binomial regression models to estimate adjusted prevalences of symptoms across tertiles of hair Hg, with stratification by serum EPA+DHA.

Hair Hg was not associated with any menstrual symptoms in the multivariable models. However, among women with high EPA + DHA, lower adjusted prevalences of experiencing sweats and hot flashes were observed in women with hair Hg in the highest tertile (0.88-5.66 ppm) compared with those in the lowest tertile (0.001-0.38 ppm); the adjusted prevalence (95% CI) for women in the lowest and highest tertile was 0.23 (0.11, 0.41) and 0.09 (0.04, 0.18), respectively. Among women with higher EPA+DHA levels, lower adjusted prevalences of experiencing migraines/headaches were observed in the middle and highest Hg tertiles compared with those in the lowest tertile [adjusted prevalence (95% CI) for lowest to highest tertiles was 0.14 (0.06, 0.29), 0.04 (0.01, 0.15), and 0.04 (0.01, 0.11), respectively].

High concentrations of serum n-3PUFAs appeared to mitigate certain symptoms among women with elevated hair Hg concentrations.