LAUSR

β-Glucuronidase was positively associated with Hispanic ethnicity, C-reactive protein, body mass index and total fat mass, but not menopausal status nor lean mass, with future studies required to understand mechanistic underpinnings for these findings. Abstract Objectives Many dietary polyphenols with potential health-promoting benefits undergo hepatic conjugation and circulate as inactive glucuronides that can be cleaved by ß-glucuronidase to reform the bioactive aglycone. Although indirect evidence suggests estrogen may induce ß-glucuronidase, little is known about ß-glucuronidase regulation across women's reproductive lifespan. Correlates of serum ß-glucuronidase activity in healthy premenopausal versus postmenopausal women were therefore examined. Methods ß-Glucuronidase activity and C-reactive protein (CRP) were assayed in stored serum from the Women's Breast and Bone Density Study, and dual-energy x-ray absorptiometry and anthropometry assessed body composition. Participants were premenopausal (n = 133) or postmenopausal (n = 89), and Hispanic (37%) or non-Hispanic White (63%). Multivariate linear regression models tested associations between ß-glucuronidase and menopausal status, ethnicity, CRP, and body composition metrics, overall and stratified by menopausal status. Results Postmenopausal (vs premenopausal) women were older (60.4 ± 3.7 vs 44.8 ± 2.4 y) with a lower Hispanic ethnicity prevalence (27% vs 44%), and higher serum ß-glucuronidase activity (1.5 ± 0.8 vs 1.3 ± 0.5 U/L) and CRP (4.2 ± 4.4 vs 3.3 ± 4.7 mg/L). Adjusting for confounders, ß-glucuronidase was positively associated with Hispanic ethnicity, CRP, body mass index, and total fat mass (all, P < 0.01), but not menopausal status nor lean mass. Central adiposity measures were also positively associated with ß-glucuronidase with the same covariates. Conclusions ß-Glucuronidase enzyme activity, upon which polyphenol health-related benefits may depend, is not associated with menopausal status. Future studies are required to determine clinical significance and mechanisms driving ß-glucuronidase associations with ethnicity, inflammation, and adiposity in women.