Gut by Giulia Enders
The gut is a complex place. Humans are coelomates, which means our our bodies are open to the outside. Our digestive system is a tube with openings at the mouth and anus that decides whether or not everything that enters the body can pass into the bloodstream.
The digestive process begins in the mouth as saliva and enzymes start to break down food. In the stomach, acid and enzymes continue to break down food, and a mucosal lining protects the wall of the stomach from acid and bile. The stomach is tilted so that food does not travel back to the esophagus, and liquids can pass more quickly to the small intestine because they do not require as much digestive activity as solids.
The gut is home to trillions of bacteria, archaea, and eukaryotic organisms. Most of the bacteria in the digestive tract is found in the large intestine, or colon. If bacteria from the colon migrates to the small intestine, due to inflammation, the result is Small Intestine Bacterial Overgrowth, or SIBO. In a gut with SIBO, food that does not digest properly at the beginning of the system ferments and feeds the bacteria in the small intestine. Symptoms of SIBO include bad breath, excessive gas and bloating, and digestive issues like constipation.
Most humans do not have too much stomach acid. Often, the problem is the reverse.
Too little stomach acid, combined with bacteria imbalances and inflammation, leads to a cycle in which undigested food feeds unfriendly bacteria, which causes inflammation and a malfunctioning of the valve that separates the esophagus from the stomach. When this valve can no longer remain closed when necessary, what little acid the stomach has travels to the esophagus and creates pain. Antacids introduce bases into the stomach to raise the pH, which means the problem of undigested food cannot be resolved. Antacids might reduce pain associated with heartburn, but since the underlying problems of bacterial imbalance and inflammation are not addressed, they ultimately make a bad situation worse.
Western medicine relies heavily on antibiotics, often in situations where antibiotics are inappropriate or can do more harm than good.
In life-threatening situations, antibiotics are necessary and worth the negative consequences. However, for chronic, non-life-threatening infections and viruses, rampant antibiotic usage results in gut dysbiosis, which may never be fully remedied.
The gut and the brain are intimately connected.
Most of the body's nerves are located in the gut. The gut is responsible for creating happiness molecules and releasing and recycling melatonin, which regulates the sleep cycle. Microbes in the gut create serotonin, so an imbalanced gut can lead to mood disorders, including depression. Toxoplasma gondii is a parasite carried by cats that can affect humans' personalities and moods.
Gut, by Giulia Enders, is a great introduction into the gut, especially if you have no background in the topic. Themes are reduced to simple explanations in layman's terms with fun analogies and light humor. At the same time, however, Enders summarizes recent findings in the scientific literature regarding the identified species of microbes living symbiotically in the gut.
Its major shortcoming is the author's acceptance of explanations and remedies offered by modern medicine for many ailments. For example, she believes that consumption of saturated fat found in animal products leads to obesity, and NSAIDS are an appropriate treatment for inflammation. Also, she describes Inflammatory Bowel Disease (IBD) as being a disease that can be treated with a variety of medications, rather than a collection of symptoms caused by a disruption in the gut.