Environmental Pollutants and the Gut Microbiome

June 12, 2020

Jodi Flaws is a Professor of Comparative Biosciences and the Principal Investigator at the Reproductive Toxicology Laboratory in the College of Veterinary Medicine at the University of Illinois. Her lab studies the effects of environmental pollutants on the development and function of the human body, specifically relating to endocrine and reproductive health. Joining her is Karen Chiu, a PhD student whose work focuses on the impact and mechanism of various chemicals on the gut microbiome.

On the podcast today Dr. Flaws and Karen Chiu discuss some of the health-damaging chemicals that have become ubiquitous in our food supply, personal care items, and even our carpeting and mattresses. They describe some of the physiological effects of these pollutants, including potentially deleterious changes to the gut microbiota and early reproductive aging. They also share tips for reducing and mitigating exposure to these compounds.

After recording this podcast Karen talked with me a bit about organic foods - are they worth the additional cost to avoid some of these toxic chemicals? It turns out that while they are exposed to fewer pesticides, hormones, and antibiotics than conventional foods, it’s not true that organic foods are totally free of these contaminants. If you see the "USDA Organic" label, you can assume the food is at least 95% organic, while a product that claims to be “made with” organic ingredients is at least 70% organic. In her opinion, organic foods and products are the way to go when possible, given their lighter chemical load. It’s always a good idea to wash your produce to get as much of the pesticide residues off whether it be organic or conventional.

Here’s the outline of this interview with Jodi Flaws and Karen Chiu:

[00:00:30] Paper: Chiu, Karen, et al. "The Impact of Environmental Chemicals on the Gut Microbiome." Toxicological Sciences (2020).

[00:01:25] Background and interest in environmental chemicals.

[00:03:35] Endocrine-disrupting chemicals.

[00:04:37] Phthalates and how they affect the body.

[00:06:08] Effects of Phthalates on the microbiome.

[00:07:15] Butyrate; Podcast: Microbiome Myths and Misconceptions, with Lucy Mailing, PhD.

[00:08:58] Potential effects of pesticides: increased lipid accumulation, decreased glucose tolerance, increased expression of adipogenic genes; Review: Xiao, Xiao, John M. Clark, and Yeonhwa Park. "Potential contribution of insecticide exposure and development of obesity and type 2 diabetes." Food and Chemical Toxicology 105 (2017): 456-474.

[00:10:44] Reducing exposure to phthalates.

[00:12:26] Environmental Working Group (EWG) database.

[00:14:09] Bisphenols.

[00:16:51] "BPA-free" - not necessarily safer.

[00:18:13] Effects of bisphenols on the gut microbiome.

[00:18:43] Bisphenol exposure in mice, effects on microbiome; Study: Javurek, Angela B., et al. "Effects of exposure to bisphenol A and ethinyl estradiol on the gut microbiota of parents and their offspring in a rodent model." Gut Microbes 7.6 (2016): 471-485.

[00:19:00] Akkermansia beneficial for intestinal immunity; Study: Ottman, Noora, et al. "Pili-like proteins of Akkermansia muciniphila modulate host immune responses and gut barrier function." PloS one 12.3 (2017).

[00:20:24] Podcast: How to Use Probiotics to Improve Your Health, with Jason Hawrelak, PhD.

[00:21:12] Persistent organic pollutants: polychlorinated biphenyls (PCBs), Polycyclic aromatic hydrocarbons (PAHs), Perfluorochemicals (PFCs), flame retardants and their adverse health effects.

[00:24:42] Exercise can attenuate change in the gut microbiome caused by PCBs; Study: Choi, Jeong June, et al. "Exercise attenuates PCB-induced changes in the mouse gut microbiome." Environmental health perspectives 121.6 (2013): 725-730.

[00:25:54] Hepcidin; Podcast: The Athlete’s Gut: Why Things Go Wrong and What to Do About It, with Megan Hall.

[00:27:20] Strategies for limiting exposure.

[00:29:20] Heavy Metals - lead, cadmium, arsenic and their effects on the microbiome.

[00:32:49] Higher arsenic levels can lead to higher Citrobacter population; Study: Wu, Fen, et al. "The role of gut microbiome and its interaction with arsenic exposure in carotid intima-media thickness in a Bangladesh population." Environment international 123 (2019): 104-113.

[00:33:29] Arsenic exposure increases TMAO; Study: Kuroda, Kaoru Yoshida Yoshinori Inoue Koichi, Hua Chen Hideki Wanibuchi Shoji Fukushima, and Ginji Endo. "Urinary excretion of arsenic metabolites after long-term oral administration of various arsenic compounds to rats." Journal of Toxicology and Environmental Health Part A 54.3 (1998): 179-192.

[00:34:18] Chris Masterjohn and Chris Kressor on TMAO.

[00:34:40] Glyphosate alters gut microbiota; Studies: Blot, Nicolas, et al. "Glyphosate, but not its metabolite AMPA, alters the honeybee gut microbiota." PloS one 14.4 (2019) and Aitbali, Yassine, et al. "Glyphosate based-herbicide exposure affects gut microbiota, anxiety and depression-like behaviors in mice." Neurotoxicology and teratology 67 (2018): 44-49.

[00:40:33] Pig GI tract similar to humans; Dr. Sharon Donovan.

[00:42:34] Siloxanes (silicone products).

[00:43:52] Siloxanes; Associated with hypothyroid in cats: Poutasse, Carolyn M., et al. "Silicone pet tags associate tris (1, 3-dichloro-2-isopropyl) phosphate exposures with feline hyperthyroidism." Environmental science & technology 53.15 (2019): 9203-9213; associated with age of menopause: Chow, Erika T., and Shruthi Mahalingaiah. "Cosmetics use and age at menopause: is there a connection?." Fertility and sterility 106.4 (2016): 978-990.

[00:45:03] Nicolas Taleb; Incerto series.