How Healthy Gut Bacteria Support Digestive Health

Filed Under: Digestive Health, Gut Bacteria & Probiotics
Last Reviewed 09/03/2015

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I’ve written at length how microflora in the gut benefits our overall health. The ways in which this occurs make for an impressive list—so much so that it’s possible to lose track of these microorganisms’ more immediate effects, which occur in the digestive tract itself.

Here are a few of the most important ways healthy gut bacteria help keep the digestive system working smoothly:

Gut Bacteria Help Digest and Absorb Foods

The most plentiful and important bacteria in the small intestine is the Lactobacillus species. Lactobacillus helps ferment indigestible carbohydrates and, as I mention below, supports the breakdown of sugars in dairy products, which are a common source of food sensitivities. As a byproduct of its fermentation process, Lactobacillus bacteria produce lactic acid. In addition to its impact on our immune system, lactic acid helps improve the release of digestive juices and enzymes from the stomach, the pancreas, and the gallbladder, and it increases the absorption of minerals such as calcium, copper, magnesium, and iron.

See a list of all articles about Gut Bacteria in the Gut Bacteria and Probiotics Index

Another lactic acid–producing bacteria, Bifidobacterium, is most densely populated in the large intestine, or colon. Like Lactobacillus, it produces lactic acid and helps with the breakdown of carbohydrates, fat, and protein during digestion, breaking food down into smaller components that the body can more readily absorb and use. Unfortunately, the amount of Bifidobacterium that naturally occur in our bodies declines with age. This is particularly true after the age of 70, making the regular consumption of fermented foods, and/or use of a probiotic supplement, essential for keeping the digestive process working at its best.

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Gut Bacteria Acidify the Colon and Normalize Bowel Movements

In a separate discussion about how gut bacteria help strengthen the immune system, I explain how the byproducts of microflora metabolism help keep the colon slightly acidic. Among these acidifiers are acetic, butyric, and lactic acids. They make the environment less hospitable to pathogenic bacteria (particularly gas-producing bacteria, which thrive in a slightly alkaline pH range of 7.2 to 7.3) an decrease the likelihood that these organisms can take root and grow. An ideal digestive pH is between 6.7 and 6.9. (Learn how to measure your bowel's pH.)

Lactic acid, in particular, plays a role in the production of the neurotransmitter acetylcholine. Acetylcholine facilitates the transmission of nerve impulses that cause muscle contractions. Within the digestive system, it helps increase the motility of the bowel (a smooth muscle) and alleviate constipation problems. 

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Gut Bacteria Eliminate Gas Problems and Sweeten Your Breath

One of the issues that often motivates people to learn more about gut health (and to try probiotic supplements) is excessive gas and bloating. Usually this gas is expelled through the digestive tract, but it also can manifest as chronic bad breath (halitosis), since gas can be reabsorbed into the blood, released in the lungs, and exhaled.

Gas has a number of causes. The inability to fully break down and digest foods is one of them, and an overgrowth of undesirable bacteria is another. Many gas-producing bacteria are the pathogenic type that thrive in a slightly alkaline environment. As noted, maintaining healthy gut flora helps keep the pH balance of the digestive tract acidic, which makes it more difficult for the more noxious bacteria to take hold.

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Gut Bacteria Support the Ability to Digest Dairy Products

Our bodies need a sufficient supply of digestive enzymes in order to break down food efficiently and effectively. The enzyme lactase is necessary to digest lactose, the sugar in milk and milk products. Without enough lactase, an intolerance to dairy products is almost guaranteed. Research has shown that individuals who have a sensitivity to milk as well as high levels of the Lactobacillus species of bacteria—which is known to produce lactase—are better able to tolerate dairy products in their diet.

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Read More About Gut Bacteria and Digestive Health

Gut Bacteria and Probiotics Article Index
See a full list of articles by Dr. Williams about gut flora, probiotics, and the microbiome. Read more
9 Ways that Good Gut Bacteria Support Your Overall Health (That Have Nothing to Do With Digestion)
Learn about the wide-ranging health effects of gut bacteria, including their influence on immune health, mood, and weight management. Read more
Lifestyle Habits That Damage Gut Bacteria
Learn how our normal, everyday routines can damage the microflora in our gut. Read more
How to Restore and Improve Gut Bacteria
Learn three strategies for restoring your gut health by improving its microflora. Read more


DISCLAIMER: The content of is offered on an informational basis only, and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified health provider before making any adjustment to a medication or treatment you are currently using, and/or starting any new medication or treatment. All recommendations are "generally informational" and not specifically applicable to any individual's medical problems, concerns and/or needs.

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