As a practitioner who has been using stool testing for the last five years.

I have developed a keen interest in Faecal Secretory IgA (SIgA) and its significance in understanding the gut terrain.

Particularly it’s relationship to food allergies, sensitivities and fighting infections.

In this post, I will explore the importance of maintaining healthy SIgA levels for overall health and well-being. As well as how low SIgA levels can adversely affect your gut health, immune health and tolerance of foods.

Moreover, I will share my approach to boosting SIgA levels clinically through supplements and diet.

What is Secretory IgA and Why is it Important?

Secretory IgA (SIgA) main role is to act as the body’s first line of defence against the entry of foreign substances into the body.

This makes it crucial for maintaining a robust immune system.

Foreign substances it defends includes:

  • Bacteria
  • Viruses
  • Parasites
  • Toxins

Because of it’s role in protecting the body against these foreign substances, it is heavily located in the mucosal lining of the gastrointestinal tract, genitourinary system and respiratory tract.

To stop the invader from doing any damage, SIgA will attach to the foreign substance, trapping them in the mucus and neutralising the threat.

In the case where SIgA levels are low, which may be discovered through a Microbiome stool test, referred by a Naturopath. It means that the body’s first line of defence is compromised, leaving it more susceptible to infections, toxins, and allergens.

Signs you may have Low Secretory IgA

Low levels of secretory IgA (sIgA) are often observed in individuals with a weakened immune system (e.g. recurrent colds, flus or gastroenteritis), anxiety, chronic stress or exhaustion.

If you suffer with the following health conditions it may be a sign you have low SIgA:

  • Asthma
  • Eczema
  • Psoriasis
  • Chronic gut infections (e.g. parasite infection, dysbiosis, candida)
  • Food sensitivities
  • Ulcerative colitis
  • Crohn’s disease

In my professional experience, people with low levels of SIgA may struggle with overcoming gut problems or skin conditions, allergies and sensitivities until their SIgA levels are normalized.

It’s important to note that certain medications, such as anti-inflammatories and antidepressants, can also cause low levels of SIgA. Interestingly, studies have shown a correlation between low SIgA and depression.

It’s crucial to understand that a SIgA test alone cannot determine the underlying cause of the issue, but it does provide a valuable clue for further investigation. Therefore, it’s recommended to work with a Naturopath who can identify the root cause behind the low SIgA levels and provide an effective treatment plan.

How Can I Raise My Secretory IgA Levels?

1. Manage Your Stress

In my clinical experience, I have noticed that people who have experienced stress, whether it be from a major life event, work-related stress, or family-related stress, often have low levels of SIgA.

Research suggests that stress and elevated cortisol levels can suppress the production of Secretory IgA, which is responsible for the body’s first line of defense against infection.

Chronic elevation of cortisol levels can lead to a decrease in SIgA production, which ultimately increases the risk of infection. This is the reason why those who experience anxiety and chronic stress, end up with recurrent colds and flus.

It’s important to note that perceived stress can also have an impact on SIgA levels. If you are experiencing gut health issues, skin problems, or sleep disturbances, stress could be a contributing factor that’s affecting your SIgA levels.

In those who experience high levels of cortisol and anxiety, herbs such as passionflower, withania and chamomile can be useful to bring cortisol down.

As part of my approach to improving gut health, I always consider lifestyle factors, not just food and supplements.

Are you getting enough sleep, exercise, and sunlight exposure? These lifestyle interventions can play a critical role in supporting an increase in SIgA levels and overall immune function.

2. Check your Zinc Levels

Research has shown that increasing your zinc intake can help improve your SIgA levels. Even if you are currently getting the recommended amount of zinc each day, which is 14mg for adult men and 8mg for adult women, zinc deficiencies can still occur depending on gastrointestinal absorption and medications you may be on that could be depleting zinc.

Working with a naturopathic practitioner who can refer you for a serum zinc blood test, can be really beneficial to determine if supplementation is required.

If you follow a vegan or vegetarian diet, it can be especially important to focus on increasing your zinc intake, as many of the zinc-rich foods are typically found in meat and seafood such as oysters and fish.

2. Probiotic and Prebiotic Support

Certain strains of beneficial bacteria and prebiotic fibres have been shown to increase faecal secretory IgA.

Those that I commonly use in my clinic include:

  • Saccharmoyces boulardii
  • Lactobacillus rhamnosus (LGG)
  • GOS (galacto-oligosaccharides)
  • FOS (fructo-oligosaccharides)
  • Colostrum


SIgA is really important for the lining of your gut. Many studies have shown that it helps keep your gut healthy by fighting harmful microorganisms and toxins, calming down inflammation, keeping your gut bacteria in balance, and protecting you from reacting to things in your gut that could make you unwell.

Do you want to know if you have low secretory IgA? Book an initial consultation and I can refer you for a microbiome test.


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