The Importance of Oral Tolerance

Oral tolerance is how your body learns to tolerate and not overreact to things you ingest orally, such as food, beverages, and even helpful bacteria. Instead of attacking these harmless substances, your immune system stays calm. This helps prevent allergies, food sensitivities, and inflammation (Chirdo et al., 2018).

Development of oral tolerance starts at birth. Poor tolerance leads to food allergies and sensitivites

Your digestive system, especially your gut, plays a big part in oral tolerance. Special cells check what’s coming in and send messages to the immune system. These messages help your body decide what is safe and what is not (Mucida et al., 2007).

Why Is Oral Tolerance Important for Autoimmune Diseases? 

Autoimmune diseases happen when your body’s immune system mistakenly attacks healthy parts of your body. Some examples are type 1 diabetes, rheumatoid arthritis, and multiple sclerosis (Pabst & Mowat, 2012). When oral tolerance is strong, it is less likely that the immune cells will indiscriminately harm your body. This leads to good self tolerance (Weiner et al., 2011).

What Does SIgA (Secretory Immunoglobulin A) Do? 

SIgA is a special kind of antibody found in saliva and other fluids. It sticks to beneficial bacteria and food pieces to mark them as safe from immune response. This is called "immune exclusion" (Macpherson et al., 2008).

SIgA teaches the immune system to not overreact by tagging harmless substances so your body can process them without initiating the body's defenses. This keeps inflammation low and your gut healthy  (Pabst & Mowat, 2012).

Why Chewing Matters. 

Chewing your food thoroughly is important for both digestion and immune health. When you chew, you break food into smaller parts and mix it with saliva. Saliva has helpful enzymes and SIgA. This boosts oral tolerance.

Doctors suggest chewing each bite 20 to 30 times or until it feels soft like paste. Chewing also makes more saliva, which keeps your mouth moist and helps stop infections and inflammation (American Dental Association, 2020).

What If You Don’t Have Enough Saliva? 

Saliva is very important for oral tolerance. It helps coat and break down food. It also carries SIgA, which protects your mouth and gut from inflammatory immune responses (Humphrey & Williamson, 2001). Without enough saliva, your body might not digest food properly and could lead to inflammation and even leaky gut.

Massaging the areas of the face where these glands are located can stimulate salivation.

A dry mouth, also called xerostomia, can happen from certain medications, stress, or health issues. It can cause cavities, infections, and trouble eating or talking (Villa et al., 2015).

How Can You Make More Saliva? 

One of the easiest ways to make more saliva is to chew. Chewing sugar-free gum or crunchy foods like carrots or almonds helps. Sour candies or lemon juice can also help, but be careful if you have sensitive teeth. Herbs such as Korean ginseng, ginger, and fennel can address a chronic issue at a deeper level (Dodds et al., 2005).

Drinking lots of water is crucial. Being dehydrated makes it harder to produce saliva. Try sipping water throughout the day and include electrolytes or trace minerals.

Other Helpful Tips. 

Breathe through your nose instead of your mouth to keep saliva from drying out. Brushing and flossing regularly keeps your mouth healthy. Sprays or lozenges may also be beneficial. Avoid things such as smoking, caffeine, and alcohol since they tend to cause dry mouth. Some medicines may also be responsible, so talk your doctor to see if xerostomia is a side effect (Villa et al., 2015).

Oral tolerance keeps your immune reactivity low and is key in prevention and management of autoimmune diseases. SIgA and saliva are crucial to this process. If you don’t have enough saliva, it can cause problems—but the good news is that there are many ways to help your body make more.

Be well!

Dr Krista J Essler, DTCM, LAc

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References

American Dental Association. (2020). Chewing and digestion: Why chewing is important. https://www.ada.org/resources/research/science-and-research-institute/oral-health-topics/nutrition

Chirdo, F. G., Millenaar, F. F., & Mucida, D. (2018). Cell-mediated tolerance in the intestine. Seminars in Immunology, 30, 59–67. https://doi.org/10.1016/j.smim.2017.08.001

Dodds, M. W., Yeh, C. K., & Johnson, D. A. (2005). Saliva and host defense mechanisms. Dental Clinics of North America, 49(1), 17–28. https://doi.org/10.1016/j.cden.2004.10.002

Humphrey, S. P., & Williamson, R. T. (2001). A review of saliva: Normal composition, flow, and function. The Journal of Prosthetic Dentistry, 85(2), 162–169. https://doi.org/10.1067/mpr.2001.113778

Macpherson, A. J., Geuking, M. B., & McCoy, K. D. (2008). Immune responses that adapt the intestinal mucosa to commensal intestinal bacteria. Immunology, 115(2), 153–162. https://doi.org/10.1111/j.1365-2567.2005.02174.x

Mucida, D., Park, Y., & Cheroutre, H. (2007). From the diet to the nucleus: Vitamin A and TGF-β join efforts at the mucosal interface of the intestine. Seminars in Immunology, 19(5), 318–326. https://doi.org/10.1016/j.smim.2007.05.004

Pabst, O., & Mowat, A. M. (2012). Oral tolerance to food protein. Mucosal Immunology, 5(3), 232–239. https://doi.org/10.1038/mi.2012.4

Villa, A., Connell, C. L., & Abati, S. (2015). Diagnosis and management of xerostomia and hyposalivation. Therapeutics and Clinical Risk Management, 11, 45–51. https://doi.org/10.2147/TCRM.S76282

Weiner, H. L., da Cunha, A. P., Quintana, F., & Wu, H. (2011). Oral tolerance. Immunological Reviews, 241(1), 241–259. https://doi.org/10.1111/j.1600-065X.2011.01017.x

Images

Oral Tolerance Induction https://www.mdpi.com/2304-8158/11/21/3386

Salivary Glands https://www.researchgate.net/figure/Illustration-of-salivary-glands-types-and-position_fig1_359172959