What is the mucosa
Did you know that your largest protective barrier from the outside world is your mucosa?
It’s true, while the surface area of our skin is about 20 square feet, the mucosal lining inside the body covers about 4000 square feet, in body tissue like the skin, respiratory, reproductive, and digestive tracts lining all entry points into the body (1) (2).
And, it is in the mucosa that the largest part of our immune system resides, with most, 70-80%, of our immune cells found in the gut (1) (3).
The mucosal lining is one of the first lines of defense against bacterial infections as it prevents the microbes from direct contact with the epithelial cells of our body (3).
Functions of the mucosa
The mucosa, or mucous membrane, secretes hormones, as well as mucus that helps food to pass through the digestive tract and protects organs of the body from being digested by the enzymes (also secreted by the mucosa) working to break down the food that we eat (4).
The mucosa also absorbs end products of digestion like glucose, amino acids, and fatty acids into the blood, and, of course, it protects us against infectious disease (4).
The mucosa protects us from infections
When a pathogen attempts to enter the body through the digestive tract, it must first pass through three barriers; the intestinal microbiota, the epithelial layer, and the mucosal immune system (3).
The intestinal microbiota consists of a community of microbes like bacteria, viruses, and fungi. This microbial community works to ensure that pathogens do not infect the body. For example, commensal bacteria like lactobacilli trigger the release of cytokines like IFN-beta and gamma that alert the innate immune system that a virus is present (1). However, when the microbiota of the gut is out of balance (dysbiotic), this can leave a “gap” in this part of the protective barrier which can lead to infection from pathogens (5).
The epithelial layer of the gut is just one cell thick! This structure makes sense when you consider that nutrients from the foods that we eat get absorbed through this layer into the blood to be used by the body for growth, development, and to sustain life. In addition to the role of nutrient absorption this one-cell-thick lining also provides a physical barrier that helps to protect the body from infections by pathogens (5). However, certain toxins can disrupt the tight junctions of this barrier which can allow pathogens to enter the body.
The mucosal lining of the epithelial barrier protects against pathogenic infections as it acts as a repository for antimicrobial molecules like IgA and defensins that can destroy or destabilize infecting agents like viruses (6). And as a part of the innate immune system, the mucosa provides nonspecific protection against infectious pathogens as a physical barrier (3).
Food that supports a healthy mucosa
With over 70% of our immune cells found in the gut (GALT), optimizing our nutrition would be supportive of immune cell function and allow the system to work effectively for us in neutralizing pathogens that would infect the body.
The immune system requires energy, so consuming healthy whole foods like vegetables, fruits, and whole grains can be supportive.
Protein sources like lean meat, fish, nuts and seeds, and vegetables like spinach can supply amino acids like arginine which is essential for the nitric oxide production of macrophages that kills bacteria and other parasites in the body (7).
Foods high in vitamin A and zinc like eggs, dark leafy greens, apricots, peaches, oysters, crab, baked beans, cashews, yogurt, and almonds will help to support cell division for a successful immune system (7).
Consuming foods like yogurt and kefir that contain certain helpful bacteria like Lactobacillus rhamnosus can help to reduce intestinal inflammation and enhance barrier function (7) (8).
The mucus layer has a protein core abundant in the amino acids serine, threonine, and proline (9). Foods rich in these amino acids include lean meats, fish, eggs, seaweed, spirulina, and venison.
Choosing to eat a diet rich in healthy whole foods, such as those mentioned, can help to support both the mucosa and the immune system for a healthier body.