As outlined in the “psychiatry” associated causes of SIBO article, digestive deficiencies are strongly correlated with small intestinal bacterial overgrowth. In fact, it is highly unlikely that bacteria would be able to grow in the harsh environment of the upper small intestine (duodenum), as seen in some people, without significant digestive dysfunction. Stomach acid and bile are strong opposing substances that help to sterilize the intestines from bacteria on our food, as well as provide digestive support for both proteins and fats, respectively.
The most common cause of digestive dysfunction, by far, is human induced! Medications that suppress acid production or over the counter anti-acids act to stop of neutralize stomach acid. This acid suppression or neutralization creates a very large risk for small intestinal bacterial overgrowth, especially when combined with the standard American diet (SAD). Medications such as proton pump inhibitors, Histamine-2 antagonists (zantac), calcium carbonate anti-acids (tums or rolaids), taking sodium bicarbonate (baking soda) or alkaline water, as well as bismuth containing preparations like Pepto can all affect our digestion through reducing or neutralizing acid production.
Suppression of stomach acid also leads to poor protein digestion, which contrary to popular belief can actually feed small intestinal bacterial overgrowth, resulting from the putrefaction of protein. Putrefaction is the process where by undigested protein “rots” in the small intestine causing the release of large amounts of nitrogen into the blood stream that can affects our liver, kidneys and brain. Once the nitrogen group is removed by certain bacteria many amino acids that make up protein can be eaten by bacteria and yeast.
Suppression of stomach acid also leads to reduced signalling from hormones originating in the stomach that stimulate the secretion of bile and pancreatic enzymes. Pancreatic enzymes are also critical in contributing to SIBO because these enzymes are what help our bodies digest the starches (sugars) that bacteria are mostly thought to eat.
Part of how the digestive system is designed to work is alternating alkaline and acidic environments. Our mouths are meant to be alkaline and this is where the digestion of starch in our diet begins. Our stomachs are meant to be acidic to help sterilize our foods and start the process of protein digestion, once the acidic content of the stomach is moved into the small intestine, the pancreas dumps bicarbonate and enzymes onto the food, while the gallbladder is meant to contract and dump bile into the mix to help solubolize fats for further digestion.
When stomach acid is not produced, further digestive processes are also suppressed leading to a “terrain” that is ideal for SIBO! Low stomach acid (achlorhydria or hypochlorhydria) also reduces gastric emptying time which results in the symptoms of functional dyspesia or indigestion. This is a real problem that affects many people, causing great discomfort after eating by leading to prolonged fullness following meals which can also result in what people experience as heart burn. In more extreme cases functional dyspesia is actually gastroparesis, is literally paralysis of the stomach where little or no stomach emptying occurs. .
Ironically the treatment of heart burn actually causes the worsening of the functional dyspepsia in most people. We will consider motility issues that occur as a result of, or that cause SIBO, in future posts.