Secretory IgA is Another Compelling Reason to Breastfeed as Long as You Can

Autoimmunity & Healing Diets

Mar 12
Secretory IgA, breastfeeding, breastmilk

It turns out that a Secretory Ig is another compelling reason to breastfeed as long as you can. It is a protective molecule found in breast milk.

We all know that breast feeding a baby is best for many reasons. It is the perfect source of fats, carbohydrates and proteins for baby.

We also know that your baby’s microbiome starts with the first sip of breast milk apart from the bacteria they pick up from the mother while passing through the birth canal. A recent study gives us new scientific evidence that mother’s milk contains critical immunological components that protect the baby’s mucosal linings from inflammation and infection.

What is Secretory IgA (SIgA)?

We have long known that human breast milk contains a substance called Secretory IgA (SIgA). The job of SIgA is to protect the mucosal linings in the body. These include all of the surfaces linking the digestive tract from the mouth to the anus, as well as the nose, the lungs, the eyelids, ears, reproductive organs and urinary tract.

The mucosal linings are thin membranes of epithelial cells that are involved in absorption and secretion of substances that aid in nutrient metabolism. Nature, in her infinite wisdom has made different mucosal cells that are based on their specific function. For example, the cells in the stomach mucosal lining are capable of secreting substances needed for the breakdown of food. They are also capable of withstanding the highly acidic environment of the stomach.

In contrast, the lining of the oral cavity, while it may differ in separate areas depending on the specific mechanical demands of the particular area, is not adapted to withstand the acid environment of the stomach – the specialized cells are adapted to their own milieu.

The mucosal linings are the largest producers of SIgA in the body – secreting between 3 to 5 grams of antibodies into the lumen of the intestine every day.

What Does Secretory IgA Do?

Secretory IgA is an antibody that is critical to mucosal immunity. It starts with IgA, which has two subclasses (IgA1 and IgA2). It’s dimeric form is the secretory form that is found in mucous secretions from all of the above mentioned mucous membranes.

The secretory part of (S) IgA  protects the immunogloblin component (IgA) from being degraded by the acids and enzymes also present in the mucous membranes. It also protects the IgA from the bacteria present in these body secretions.

In this way, it helps the immune system function properly.

What is the Importance of Secretory IgA?

SIgA plays an important role in preventing pathogen adhesion to host cells, therefore blocking the spread of infection. However, SIgA antibodies act in a more complex way to include intracellular and serosal (blood) neutralization of antigens, activation of non-inflammatory pathways to counter inflammation, and the ability to control and balance the endogenous microbiota.

This translates into having a healthy body that responds appropriately to foreign particles without the cascade of inflammation typical of the allergic response. We are seeing a dramatic increase in allergies and asthma in children (and adults). When it comes down to the cellular level, SIgA is critical.

In fact, we are finding out that SIgA is critically important to the control of commensal bacteria.

Setting up a developing child with good bacteria is the start to a healthy life. Clearly, SIgA plays a large part in that orchestration.

Breast Milk is Raw

We feed our babies raw milk. Raw milk is full of life – the antibodies, immunoglobulins, microbes and other substances are all alive and protective. There are substances in the milk itself that protect it from pathogenic bacteria.

Infant formula is devoid of these important antibodies that are critical to the health of the child and the development of a healthy intestinal microbiome.

Of course, breast milk does not sit around outside of the body where it could be exposed to pathogens. It is delivered on demand, fresh and potent.

Read more about how your baby’s microbiome starts with the first sip of breastmilk.

Breastfeeding is Not Sterile

We are all way too concerned with cleanliness and sterilizing everything around us. Of course we need to protect baby against virulent microbes, but there is plenty of research showing that the more microbes a child is exposed to when young, the fewer allergies and chronic illnesses.

When you put your baby to your breast, do you swab it with alcohol first to kill germs? Of course not! But there are bacteria on your skin. These are mainly beneficial bacteria that make up part of your microbiome – the microbial communities that you will be transferring to your baby that will protect and serve the child.

How Clean do We Have To Be?

The Hygiene Hypothesis informs us to question how clean we actually need things. Research has shown that people who grow up exposed to more microbes are better off than folks who are too clean. Exposure to germs gives the immune system a chance to exercise and mature. Instead of trying to kill every microbe that comes our way — we should be encouraging the beneficial bacteria that we are made of and that surround us in our environment. Yes — we are actually made of more microbial cells than human cells.

Breast Milk – The First and Best Source of SIgA for Baby

SIgA from breast milk was found to be protective of the lungs of neonates (in mice) from pathogenic bacteria in this study published in PNAS in 2014.

In this study, the researchers used a novel approach by using mice that could produce milk that lacked the important SIgA antibodies. In this way they could isolate any influence of the antibodies from the other components of the breast milk.

The investigators set up two groups: one group of pup and adult mice reared by mothers with normal milk containing SIgA; the other group of pup and adult mice were reared by mothers with milk lacking SIgA. They went on to determine the diversity of bacteria present in the guts of both groups.

They found that the SIgA in the milk altered the levels of over 1000 bacterial species in the young mice. Importantly, this persisted after weaning into adulthood, with differences in nearly 500 bacterial species measured in older, weaned mice.

Upon examination of the lining and lymph glands of the intestines of the young mice in the group without the SIgA antibodies in their milk, they found that the absence of antibodies in breast milk was leading to higher levels of bacteria invading the lymph glands. They also found evidence of biochemical stress and altered gene expression in the epithelial cells that are part of the mucosal lining.

These changes in the diversity and balance of bacteria in the guts of mice reared on milk without SIgA were also similar to changes that have been found in humans with inflammatory bowel diseases. That’s a flag right there.

The Conclusion
The researchers concluded that,

oral administration of purified IgA could be investigated as a biological therapy for intestinal infections and inflammation, particularly in formula-fed infants…

That’s good. Maybe someday isolated SIgA will be a therapy for inflammatory bowel disease and will be safer than what is available today.

The best conclusion would be to highly recommend breast feeding baby as long as possible in order to reap the benefits of this health promoting substance in breast milk that persists into adulthood.

What do you think? Leave a comment and let me know!

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Secretory IgA is another Compelling Reason to Breastfeed as Long as You Can

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