Once thought of as only a place where food was processed and absorbed, it is now understood that the gut plays important roles in immunity, mental health, and metabolism. Many factors such as environmental toxins can affect the gut, and can cause disruptions to the epithelium and mucosa of the intestine. How do these toxins end up in the gut, and how do we get them out? Which tests would pinpoint the underlying causes of irritable bowel syndrome? Toxins such as glyphosate, mycotoxins, and other pollutants can dramatically affect the body's microbiome. Understanding how to diagnose and treat can help against weight gain, depression, anxiety, and poor immunity.