Table 4.

Chemical obesogens and their effects on the microbiome.

Chemical	Source/Use	Proposed Mechanism	Effects	References
Fructose	Fruits, vegetables, and a natural sweetener in foods and beverages.	Decrease the expression of tight junction proteins, leading to increased intestinal permeability.	Increased intestinal permeability may allow endotoxins to diffuse through, causing chronic inflammation.	(172–174)
Artificial sweeteners or Non-Nutritive Sweeteners (NNS)	Sugar substitutes such as acesulfame potassium (Ace-K), saccharin, and sucralose, to name a few.	Decreased the relative abundance of Clostridium. Both sucralose and Ace-K decreased the abundance of Akkermansia muciniphila. Ace-K increased the synthesis of lipopolysaccharide (LPS) genes and may affect taste receptors.	NNS induced bacteriostatic effects and gut dysbiosis, leading glucose intolerance. Ace-K increased secretion of incretins, leading to weight gain. Increased LPS synthesis lead to inflammation.	(175–180)
Carbendazim (CBZ)	Agricultural fungicide and industrial preservative.	Changes in SCFA’s (short chain fatty acids) and resulted in decreased triglyceride levels. Decreased the abundance of Bacteroidetes and Verrucomicrobia and increased abundance of Actinobacteria.	Increased lipid absorption and inflammation which led to increased lipid stored as fat.	(181)
Chlorpyrifos (CPF)	Pesticide used on fruits and vegetables.	Chlorpyrifos causes microbial dysbiosis, causing in increase in Streptococcus, Ruminiclostridium, and Parasutterella and decrease in Romboutsia, Turicibacter, and Clostridium. Increased gut permeability due to decreased the expression of mRNA tight junction proteins.	Broken integrity of the gut barrier led to lipopolysaccharide entry and inflammation.	(165, 182–185)
Cadmium	Heavy metal ubiquitous in water, air, tobacco smoke, and plastics.	Low dose cadmium decreases diversity in early-life protective bacteria such as Lactobacillus, predisposing individuals to fat accumulation and obesity. Carbohydrate metabolizing bacteria such as Bifidobacterium and Prevotella are reduced.	Low-dose cadmium exposure caused increased fat accumulation and decreased bacterial diversity, especially in males.	(186, 187)
Bisphenol A (BPA)	Chemical used to make polycarbonate plastics and epoxy resins, including lining of food packaging.	Increased abundance of Proteobacteria and decreased the abundance of Bifidobacterium.	Acts in a sex-dependent manner, inducing pro-inflammation of gut microbiota primarily in females.	(170, 188, 189)
Polychlorinated Biphenyls (PCBs)	Ubiquitous chemical pollutants persistent in seafood and poultry due to their usage in dielectric and coolant fluids in the past.	Increased gut permeability, leading to increase the passage of pathogens and inflammation. Increased membrane disruptions in insulin-metabolizing murine fecal bacterium, thereby decreasing its fermentative ability.	Increased inflammation may lead to dysregulation of insulin signaling. Membrane disruptions in bacteria may cause gut dysbiosis.	(190–192)
Microplastic	Environmental pollutants commonly found in coastal oceans and terrestrial environments and includes BPA and phthalates.	Decreased mucus secretion leading to increased pathogen entry. Led to decrease of Verrumicrobia, Alphaproteobacteria, and Oscillospira and increase in Parabacteroidetes, Prevotella, Dehalobacterium, and Bifidobacterium.	May modify the gut microbiota and induce hepatic lipid disorder, particularly in male mice.	(193–196)