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It is incredible how frequently we see low levels of secretory IgA when we test our clients (via stool testing). This is both in our CFS patients as well as our patients who are seeing us for other health reasons. As a result we thought it would be beneficial to have a short article discussing what secretory IgA is, what it does, what causes it to be low, and, interventions that have proven successful, in the research and clinically, to restore healthy levels.

What Is Secretory IgA?

SIgA is an antibody that plays a critical role in immune function in the mucous membranes. More IgA is produced in mucosal linings than all other types of antibody combined; between three and five grams are secreted into the intestinal lumen each day.

Role of sIgA

Secretory IgA (SIgA) serves as the first line of defense in protecting the intestinal epithelium (the gut lining) from enteric toxins and pathogenic (disease causing) microorganisms. It does this via several mechanisms including:

Blocking of Toxins: SIgA is capable of interfering with the earliest steps in the infection process by virtue of its ability to block toxins and pathogens from adhering to the intestinal epithelium (gut lining)

Immune exclusion: this generally refers to the ability of Secretory IgA to promote the clearance of antigens and pathogenic microorganisms from the intestinal lumen by blocking their access to epithelial receptors, entrapping them in mucus, and facilitating their removal.

Prevention of microbial translocation: secretory IgA binds to luminal bacteria to prevent microbial translocation across the lining of the gut, but it also influences the balance of immune and metabolic pathways in intestinal epithelial cells.

In the absence of IgA, there is a shift toward the expression of genes involved in host defense, excessive production of antimicrobial proteins, and inflammatory-like responses

Tolerance: The antibodies also ‘tag’ foods as acceptable to the body and this suggests why low SIgA levels can be the key to developing food sensitivities. This is why we recommend stool testing over food sensitivity testing as a rule of thumb. If someone has compromised immune function within the digestive system this needs addressing!

Causes of low levels of secretory IgA

Chronic stress: can have negative repercussions on intestinal function and integrity. This can take the form of increased adhesion of pathogenic agents (something that causes disease) to the lining of the gut and/or an altered balance of inflammation leading to greater intestinal permeability.

Down modulation of SIgA associated with stress can have negative repercussions on intestinal function and integrity. This can take the form of increased adhesion of pathogenic agents to the intestinal epithelium and/or an altered balance of inflammation leading to greater intestinal permeability (leaky gut).

Chronic Infections: can cause SIgA depletion. Often we find these infections in the stool test.

Medications: Certain medications have been shown to deplete SIgA levels. Anti-inflammatories in particular tend to lower the levels of SIgA, but so to can antibiotics.

Poor dietary choices: A diet lacking in micronutrients and fibre will not be able to support a healthy immune system and response and this may contribute to low levels.

Chronically low levels can also be a sign of an ongoing ‘immune-drainer’, so to speak, in that an unsuspected immune problem is dragging the body down. This can eventually lead to fatigue.

What about elevated SIgA levels?

Elevated levels of secretory IgA suggest the individual has an activated immune response to some sort of infection. Often there will be a bacterial/viral/parasitic infection highlighted in the stool results and clearance of the infection will, in this case, likely resolve the elevated SIgA levels. If it doesn’t, further testing to understand what (or what else) is causing the result would be needed.

Recommendations for improving sIgA levels when low

Saccharomyces Boulardii:  may cause an increase in secretory IgA levels in the intestine

Culturelle: A specific probiotic that has been shown to support Il-10 production (a cytokine), which supports secretory IgA production.

Resolving Stress: chronic stress has been shown to reduce levels including chronic negative thoughts.

Colostrum: An immunoglobulin secreted in the early stages of breast-feeding. Again this has been shown to stimulate SIgA levels. Colostrum in particular is useful with those that take part in a high level of physical activity.

Mushrooms rich in Beta Glucans: These include mushrooms such as reishi, shiitake and maitake. You can get mushroom blend formulas that work very will in terms of immune modulation.

Bone Broth & Gelatine: Bone broth and specifically the gelatine it provides is said to be supportive of SIgA levels in the gut.

Choline, essential fatty acids, glutathione, glycine, glutamine, phosphatidylcholine, Vitamin C and Zinc are all required in some way or another for efficient production of SIgA so it makes sense at least to optimise those.

Obviously there will be other factors to consider, depending on what else is going on with the individual. If a chronic infection has been detected or is suspected, this will have to be dealt with also (via antimicrobials for example). There may be lifestyle interventions that need to be considered around sleep and exercise, and mindset interventions around cognition, emotions and stress.

More times than not there are several things that may need addressing, in a systematic and logical order, to fully restore health, and this is obviously based on the complexity of the individuals health and what has come up in any testing that has been completed.


Considering relevant recommendations from the above discussion, alongside the recommendations we discussed in our ‘Restoring Digestive Health‘ article, will often help resolve the imbalanced markers in the stool test. It is important to highlight, dependent on the current health of the individual, and the ability to remove the appropriate stressors from their life and body, restoring healthy levels of secretory IgA can take many months, sometimes more. This is why it is so important to have the right mentality going in to a health programme. You may like to read our article ‘Our Spiritual Journey‘ which discusses how we change our perceptions around our health and symptoms, and how the story we tell ourselves can be an important part of the process.