A prophylactic multi-strain probiotic treatment to reduce the absorption of toxic elements: In-vitro study and biomonitoring of breast milk and infant stools

Maria Luisa Astolfi,Carmela Protano,Elisa Schiavi,Elisabetta Marconi,Daniela Capobianco,Lorenzo Massimi,Martina Ristorini,Maria Elisabetta Baldassarre,Nicola Laforgia,Matteo Vitali,Silvia Canepari,Paola Mastromarino

doi:10.1016/j.envint.2019.05.012

Maria Luisa Astolfi, Carmela Protano + Show 10 more

Open Access

https://doi.org/10.1016/j.envint.2019.05.012

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Abstract

Potential exposure to toxic elements initially occurs during gestation and after birth via breast milk, which is the principal source of nutrients for infants during the first months of life. In this study, we evaluated whether maternal oral supplementation with a multi-strain probiotic product can protect infants from exposure to arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) via breast milk. In-vitro studies of the bacterial strains present in this probiotic product showed a high bacterial tolerance for As, Cd, Hg, and Pb, and good binding capacity for Cd, Hg, and Pb (72%, 81%, and 64%, respectively) within 1 h of contact. We evaluated concentrations (5 mg L−1 for Cd and Pb, and 2 mg L−1 for Hg) that largely exceeded the provisional tolerable weekly intake of these toxic elements via food or water applicable for human consumption. Changes in the levels of these elements in breast milk and newborn stools were evaluated in the control (orally supplemented with placebo) and experimental (orally supplemented with probiotic) groups at birth (t0), 15 days (t15), and 30 days (t30) after delivery. Elemental analysis of breast milk did not show significant differences between the control and experimental groups at different stages of lactation; however, stool samples obtained from newborns of mothers supplemented with the probiotic product showed that Cd levels were significantly reduced (by 26%) at t15 compared with the levels of the controls. Our data did not show an association between concentration of toxic elements in breast milk and that in newborn stools. Indeed, the concentration of Cd, Hg, and Pb in breast milk decreased during the lactation period, whereas the levels of these elements in newborn stools were stable over time. Although our in-vitro data indicate that the consortium of these probiotic strains can absorb toxic compounds, this study was limited by its small sample size and potential uncontrolled confounding effects, such as maternal diet and lifestyle. Therefore, we could not confirm whether prophylactic use of this probiotic product can reduce the absorption of toxic elements. The risk assessment in the studied population evidenced a margin of exposure (MOE) of 1, or between 1 and 10 for Pb, and lower than 50 for As. This poses a potential risk for breastfed infants, indicating that interventions aimed to avoid breastfeeding-related health risks remain a major challenge in public health.

Highlights

Chemical elements are naturally present in the environment, where their distribution is determined by biogeochemical cycles
We evaluated the effects of prophylactic treatment with a multi-strain probiotic product on the concentrations of toxic elements in breast milk and newborn stools at different time points during lactation
The bacterial strains evaluated in our study were able to tolerate and survive at up to 5 mg L−1 As, Cd, and Pb, and at up to 2 mg L−1 Hg, for 24 h in MRS broth (C1 concentration, Fig. 1)

Summary

Introduction

Chemical elements are naturally present in the environment, where their distribution is determined by biogeochemical cycles. Breast milk can be a pathway for maternal excretion of toxic elements and a potential source of exposure for infants (LaKind et al, 2004; U.S EPA, 2011; Björklund et al, 2012; Ettinger et al, 2014; Rebelo and Caldas, 2016). MeHg and IHg are teratogenic and neurotoxic, especially in the developing brain (WHO, 1991, 2010; NRC (National Research Council), 2000; JECFA, 2004; Clarkson and Magos, 2006; Ceccatelli et al, 2010) All these elements can exert serious effects on the health of children, affecting numerous systems and organs (Al-Saleh et al, 2011, 2016; Shrader-Frechette, 2012; Valent et al, 2013; Yurdakök, 2015; Rebelo and Caldas, 2016; Kunter et al, 2017). The health effects related to the intake of these elements via human milk have not been extensively studied

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