Hair mercury levels, dietary intake of omega-3 fatty acids and ovarian reserve among women attending a fertility center

Abstract

BACKGROUND AND AIM: We investigated the association of hair mercury (Hg) levels with antral follicle count (AFC), as a marker of ovarian reserve, and evaluate whether this relationship differed among women with high vs. low intake of long chain omega-3 polyunsaturated fatty acids (n3PUFA). METHODS: We included 295 women attending an academic fertility center (2007-2016) who had data on hair Hg levels (assessed using a Direct Mercury Analyser), n3PUFA intake (estimated using a validated food frequency questionnaire) and AFC (assessed by transvaginal ultrasonography and abstracted from electronic medical records). Poisson regression models adjusted for potential confounders were used to evaluate the association of hair Hg levels (divided into tertiles, and as above vs below EPA reference (1ppm)) with AFC. Associations were also evaluated after stratification by n3PUFA intake (≤0.124 vs. 0.125 %calories/week). RESULTS:Women’s median hair Hg level was 0.55 ppm (range=0.01-8.51 ppm), with more than 30% 1 ppm. Hair Hg was positively related to AFC after adjusting for age, BMI, smoking status, infertility diagnosis, and alcohol intake. However, associations became attenuated after further adjustment for intake of calories and n3PUFA. The positive associations of hair Hg and AFC were observed only among women with high n3PUFA intake. Specifically, women who consumed 0.125 %calories/week of n3PUFA had a mean AFC of 11.9, 13.2 and 14.5, respectively, across increasing tertiles of hair Hg (p=0.002). Similar results were found when hair Hg was divided as above vs below EPA reference (mean AFC=12.7 vs. 14.6, p=0.002). CONCLUSIONS:In women from a fertility clinic, positive associations of hair Hg with AFC may be reflective of beneficial effects of n3PUFA on ovarian reserve rather than a beneficial effect of Hg per se. Our findings highlight the importance of considering diet when exploring Hg effects on women’s reproductive health. KEYWORDS: Heavy metals, food/nutrition, female reproductive outcomes.