Along with the rapid development of industry and economy, the pollution of heavy metals is getting worse. Not only is the food we eat polluted, but the air pollution, drinking water and the poor-quality tableware may increase risks of heavy metal exposure. Heavy metals are natural components of the Earth's crust, so they cannot be degraded or destroyed. To a small extent, they enter our bodies via food, drinking water and air. As trace elements, some heavy metals (e.g. copper, selenium, zinc) are essential to maintain the metabolism of the human body. Prolonged exposure to heavy metals such as cadmium, copper, lead, nickel, and zinc can cause deleterious health effects in humans. Hence, how to decrease the lead exposure in daily life is very important.
 
In Taiwan, most people like to use Chinese medicine for health care and medicinal cuisine and most of the them depend on import. The Chinese medicinal materials market extends all over the country so that the source is not easy to control. Multiple factors would affect the quality of the Chinese medicine such as the climate, place of origin or manufacturing process. Indeed, Chinese medicines generally may contain toxic contaminants, for example, heavy metals, pesticides and aflatoxins residue which make all consumers worry. Notably, cadmium (Cd), lead (Pb), mercury (Hg), and arsenic (As) are classified as strong carcinogens by the International Agency for Research on Cancer. Those heavy metals which accumulating in the body for a long time may cause harmful effects on hepatic, renal, and cerebral tissues or on neurological and hematological functions.
 
In recent years, studies have found that heavy metals would cause brain, nerve and liver damage even if we absorb a little concentration of them through diet. Moreover, the damage of brain and nerve would easily cause disease and loss of cognitive ability. Heavy metals has been approved to change  gut microbiota composition and break the intestinal mucosal barrier which may be a vital mediator of heavy metals bioavailability and toxicity. However, probiotics have been shown to reduce the absorption of heavy metals in the intestinal tract via the enhancement of intestinal heavy metal sequestration, detoxification of heavy metals in the gut, changing the expression of metal transporter proteins, and maintaining the gut barrier function.
 
The animal experiment published in Translational Psychiatry from Xiao et al. (2020) indicates that perturbations of the gut microbiota by lead poisoning can thus affect metabolic and physiological functions, thereby contributing to the development or progression of various diseases and nervous system damage in host. In this experiment, the group with a multi-strain probiotics blend (BL986, LA1063, LF26, LH43, LPC12, LRH10, ST30) shows the gut microbiota composition was reshaped and the richness was significantly increased. Therefore, the side effects caused by lead poisoning have been improved. Ni et al. (2019) found that Lactobacillus LC122 and Bifidobacterium longum BL986 can also balance the gut microbiota and make the brain work stably. Consequently, probiotics can reduce the harm of heavy metals and maintain healthy state.


Reference:
[1] Chi, L., Bian, X., Gao, B., Tu, P., Ru, H., & Lu, K. (2017). The Effects of an Environmentally Relevant Level of Arsenic on the Gut Microbiome and Its Functional Metagenome. Toxicological sciences: an official journal of the Society of Toxicology, 160(2), 193–204.
[2] Lu, K., Abo, R. P., Schlieper, K. A., Graffam, M. E., Levine, S., Wishnok, J. S., Swenberg, J. A., Tannenbaum, S. R., & Fox, J. G. (2014). Arsenic exposure perturbs the gut microbiome and its metabolic profile in mice: an integrated metagenomics and metabolomics analysis. Environmental health perspectives, 122(3), 284–291.
[3] Ni Y, Yang X, Zheng L, et al. Lactobacillus and Bifidobacterium Improves Physiological Function and Cognitive Ability in Aged Mice by the Regulation of Gut Microbiota. Mol Nutr Food Res. 2019;63(22):e1900603.
[4] Xiao, J., Wang, T., Xu, Y., Gu, X., Li, D., Niu, K., Wang, T., Zhao, J., Zhou, R., & Wang, H. L. (2020). Long-term probiotic intervention mitigates memory dysfunction through a novel H3K27me3-based mechanism in lead-exposed rats. Translational psychiatry, 10(1), 25.