By Amy Denney
Imagine trying to navigate your way across 150 football fields filled with waist-high gel to reach the end zone and score a touchdown.
That’s the analogy gastroenterologist Dr. Robynne Chutkan uses to describe the defenses a virus must overcome to infect us. The gel represents the mucus layer of the gut and lungs—5,000 times the diameter of a virus, she said.
“That’s a big, big buffer zone,” Chutkan, author of several digestive health books, told The Epoch Times. She wrote extensively about mucus in her book, “The Anti-Viral Gut.”
Most of us don’t give a second thought to mucus unless we happen to be sick or struggling with allergies that cause upper respiratory symptoms like a runny nose or post-nasal drip. However, we have more mucus membranes than skin coverage, and it lines our lungs, eyes, and even our entire digestive tract.
In fact, mucus is a major player in biochemical collaborations happening in the walls of the gastrointestinal (GI) tract. Thus, it’s an important feature of our body to study regarding inflammatory bowel disease (IBD) and autoimmune conditions. As an immediate shield for our immunity, it’s both highly protective and quite vulnerable—and how we eat can determine how well it fights for us.
Dr. Manisha Ghei, internist and functional/integrative physician at Praana Integrative and Functional Medicine, describes mucus this way: “Think of it like a fortress. It’s really your body’s first line of defense.”
Perhaps its highest value, she said, is to keep anything we ingest from destroying or over-activating the “biggest part of our immune system [that] lives right below that mucosal barrier.”
Many Roles of Mucus
Similar to how the slime excreted by snails allows them to slide across surfaces, mucus in the digestive tract provides lubrication that helps move stool smoothly through the digestive tract.
Mucus does this by keeping the intestinal epithelium hydrated to assist in peristalsis—the waves of contractions that move food through the GI tract. Mucus must also allow molecules from water, nutrients, and gases to penetrate through it to maintain homeostasis.
Digestion isn’t the only system mucus is involved in—it has many other jobs—mostly related to immunity.
Gut Barrier
Mucus is a sticky, slippery coating, made of micin and water, that forms a physical barrier to protect our internal organs from the outside world. Mucin is a protein constantly made and secreted by goblet cells in the intestinal epithelium.
Without the mucosal layer, pathogens could butt up against our gut lining, Chutkan said, which “is one cell thick.”
Mucus has two key jobs related to immunity, she said.
First, it’s a mechanical buffer against pathogens like viruses and bacteria. In this role, thickness and viscosity modulate how well mucus can trap bugs and flush them out through the GI tract.
Second, it also chemically activates proteins that communicate with our immune system to kill or disable pathogens.
Loss of Mucus
A number of factors can influence the breakdown of mucus, including poor diet, food additives, medicines such as proton pump inhibitors, non-steroidal anti-inflammatory drugs, and antibiotics.
“These things that erode the mucosal layer totally keep us in business as gastroenterologists,” Chutkan said. “You remove that barrier, and now you’re going to have immune activation.”
A study published in Gut found that in mice without mucin, bacteria in the colon were able to penetrate epithelial cells. The result was inflammation, diarrhea, rectal and colon prolapse, rectal bleeding, spontaneous colitis (ulcers in the intestines), and an increased risk of colon cancer.
Mucus barrier alterations play a role in the onset of IBD—ulcerative colitis and Crohn’s disease. Changes in mucus are also involved in other autoimmune diseases.
Mucosal alterations disrupt the normally tight junctions of the epithelium to increase intestinal permeability, allowing microbes to migrate into the body where they don’t belong and cause sustained inflammation. The condition is often referred to as “leaky gut syndrome.”
Anything that slips through our mucus and triggers the immune system—including digestive enzymes, bacteria, food particles, and toxic substances—can lead to an autoimmune response, Ghei said, and cause our body to begin attacking itself.
“A tight and healthy mucosal barrier is so important for health. When that starts breaking down for whatever reason, disease starts developing in the body,” she said.
Mucus Needs Microbes
One way we can support the mucous barrier is through the gut microbiome—the community of bacteria, viruses, fungi, and archaea that live along the GI tract designed to protect us from pathogens. The microbiome is involved in mucin production.
For your goblet cells to make mucin, they need the short-chain fatty acids (SCFAs) made when our gut microbes metabolize fiber from the diet.
Dysbiosis, or an unhealthy balance of microbial composition in the gut, can create barrier dysfunction because the microbiome is responsible for converting food into SCFAs.
When SCFA production decreases, the mucus layer thins and becomes more penetrable. Systemic diseases like IBD, celiac disease, food allergies, obesity, and autoimmune diseases are associated with mucosal barrier dysfunction.
“The turnover of the intestinal mucus layer includes mucus synthesis, secretion and degradation, and it is a delicate process that needs to be regulated and balanced to ensure that mucus maintains an optimal protective function,” according to the article in Gut.
Diet and Mucus
Dietary fiber can become a useful strategy for increasing mucin production, as diets with at least 15 percent of dietary fiber from minimally processed grains and plants play a role in a healthy mucosal barrier, according to the article.
Research showed that after three days of a “western-style diet”–containing mostly fats and carbohydrates and little fiber–the mucosal layer became more penetrable, the article noted. IBD is associated with diets deficient in fiber.
Diets rich in plants are associated with a more diverse microbiome that protects against leaky gut.
“Eat more plant based foods because they help create the lining,” Ghei said. “I’m not saying don’t eat meat. I’m saying plants should be more than half of your plate and a variety. Eating the whole rainbow as much as you can.”
The Gut article noted certain probiotics appear to have a positive impact on mucin production, such as Bifidobacterium longum, which can restore mucus growth, and Limosilactobacillus reuteri, which plays a role in increasing mucosal layer thickness.
Ghei said removing anything chemically-based, including ultra-processed food, soda, and alcohol, would undoubtedly favor a healthier mucosal barrier.
It’s also important to limit the use of drugs like antacids, nonsteroidal anti-inflammatory drugs, cough suppressants, and antibiotics that can be harmful to gut health, Chutkan said.
A recent study in mice discovered that in addition to killing healthy microbes that play a role in a healthy gut barrier, antibiotics also directly damaged the mucosal layer of the gut.
“These things are devastating. And I think part of the problem is there’s this chain validation of, ‘Well, everybody takes these drugs. Everybody takes antacids. Everybody takes NSAIDs.’ And yeah, well, everybody’s kind of sick, too, when you think about it,” Chutkan said.
