Could low Secretory IgA be the driving force in autoimmunity?

Reviewing the results of many of my client’s stool tests gives me meaningful insights into similarities and patterns into the underlying cause of irritable bowel syndrome and autoimmune symptoms such as fatigue, hair loss, painful joints, neurological issues and skin rashes.  


One such marker that comes up time and time again is low secretory IgA (SIgA). SIgA is the antibody hanging out at the mucosal surfaces such as the gastrointestinal tract, nostrils, eyes, genital tract and throat. It protects the barrier from external invaders and ensures that the immune system stays balanced and doesn’t go astray.

This article will explore the role of SIgA, how a SIgA deficiency can cause disease, and diet and lifestyle strategies to increase amounts in the body.

What are the impacts of low SIgA?

As SIgA is vital for the proper functioning of the intestinal barrier, those with low SIgA are far more likely to suffer from food sensitivities, IBS symptoms, and increased intestinal permeability. As these are all mediators in autoimmune disease and inflammatory conditions, it is understandable that a person with low SigA may develop these conditions over time. 

If you are experiencing food sensitivities, it is often best to have a stool test before or in conjunction with a food sensitivity test. Knowing your SIgA baseline will indicate if this is the underlying cause of the food sensitivity you are experiencing. 

As SIgA acts as your border security force, toxins, larger molecules, viruses, and other unwanted substances pass into your bloodstream when they are running low or not there to protect you at all. And when your immune system gets a glimpse of these strangers, it starts to fire a response. And with those first responders, a cascade of events prevails, leading to damaged cells, corrosive by-products and more inflammation. 

Low SIgA revealed on a stool test might not seem like a big deal, but you can see that it can lead to devastating effects in your body that may develop into chronic inflammation and autoimmune disease. 

What causes low SIgA?

Many factors can lower SIgA in the body, so pinpointing those that apply for you is essential to take action and feel better.

Here are some of the more common reasons that cause low SIgA:

Chronic gut infections 

Even if you are currently not experiencing symptoms, chronic gut infections can lay low in the digestive tract but damage insidiously over time. These infections slowly wear down the immune system, leaving it lacking the power to protect you in your times of need. 

In the stool tests I run, low SIgA is commonly presented with pathogens like Blastocystis hominis, H pylori and candida. These are opportunistic pathogens as well, so you need to decipher whether the pathogen first created the problem or whether it could thrive once SIgA decreased. 

Reviewing your current symptoms, health history, and other contributing factors such as your lifestyle, sleep, or diet will better understand this. 


Many of my clients eat a very 'clean' diet and often are perplexed about what they are doing wrong. They are well informed of their conditions, have done plenty of research into healthy foods, and live a healthy lifestyle. However, when you look a bit deeper, it becomes clear that a so-called ‘clean’ diet can lack nutrients, especially the active ones that your body can easily use.

The most common deficiencies I see are omega fats from fish and fat-soluble vitamins mainly found in animal products such as vitamin A, D, E and B12. And guess what? Vitamin A is needed to transport and release secretory IgA across the mucosa, so a deficiency in this alone can contribute to SIgA deficiency. 


The stress hormone cortisol has been shown to lower SigA in the body, and studies have revealed that managing stress can help reverse the decrease in SIgA. Given SIgA role in barrier protection in the respiratory tract, it is thought that you may be more prone to respiratory infections when stressed as a result of cortisol’s effect on SIgA. 

How can you manage your SIgA levels naturally?

If you can determine the cause of low SIgA levels, then focus on this as the first course of action. However, whether you have low levels of SIgA or not, it is best to take steps every day to make sure you keep its production in good supply. 

Start by eating an anti-inflammatory diet that is low in sugar and processed foods and includes lots of fresh vegetables, herbs and fruits, and healthy omega essential fatty acids found in oily fish and flaxseeds. 

Also, focus on adding nutrients that support the immune system, such as zinc, selenium, vitamin C and choline. Bone broth contains amino acids that help rebuild the gastrointestinal wall and boost SIgA levels, so it is excellent to add to your daily diet to keep your gut health optimal. 

Other supplements which may increase SIgA levels include saccharomyces boullardi, colostrum and medicinal mushrooms such as reishi, maitake, and shitake. However, it is best to work under the direction of a nutritionist for these types of supplements, as they can affect other areas of your health as well. 

And manage stress with regular relaxation practices such as yoga, walks in nature and meditation. Prioritise these activities over more energy-consuming ones, as living in a chronically stressed state can be a blocker to move forward when low SIgA is the culprit of your symptoms. 

How to test your SIgA levels

You can find out your SIgA levels in a stool test. I typically use the GI Effects Comprehensive Profile in my clinic, which indicates whether SIgA is low as well as insight into what is causing the decrease in SIgA levels.

You can also test IgA levels in a saliva or blood test, but as I find many of my clients’ problems start in the gut, I find the information that you get from a stool test far more applicable than those in the other tests. 

If you are experiencing chronic gut or inflammatory symptoms, a stool test might be good to start in your recovery process so you can feel better again. 

In my clinic, I am now introducing a test analysis service (exclusive of test price), which includes a health assessment, test analysis, 45-minute consultation and meal and supplement plan at an introductory price of £75 (£150 from January 2022 onwards). Please contact me here if you are interested in this offer. 

The views expressed in this article are those of the author. All articles published on Nutritionist Resource are reviewed by our editorial team.

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London W1G & Harrogate HG1
Written by V. J. Hamilton, Autoimmune Disease Expert | BSc (Immunology), DipION, mBANT
London W1G & Harrogate HG1

After 25 years of suffering from multiple autoimmune conditions that affected her energy, skin, hair and joints, VJ discovered after studying immunology and Functional Medicine and training as a Nutritionist Therapist that by uncovering the root cause of her issues, she was able to transform her health, and now lives free of symptoms.

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