The Intestine/Immune Connection

Healthy Gut and Immune System Connection

When most people think of their immune system the last thing that comes to mind is the large intestines. However, thanks to emerging research and high profile ad campaigns by companies like Dannon® yogurt, people are getting introduced to the connection.

Our large intestines are inhabited by trillions of bacteria often referred to as probiotics (pro=encouraging, biotic=life). These bacteria composed primarily of acidophilus and bifidobacterium species are introduced to our system during the birth process and play a crucial role in our health. Without probiotics, humans would be extremely vulnerable to food borne illnesses, be deficient in key nutrients and vitamins, and have a much weaker immune system in general.

Lifestyle factors play a significant role in determining how friendly our large intestines are to hosting these important bacteria. Eating a diet high in sugar, fat and processed foods prevents them from growing and thriving. Consumption of fiber from fruits, vegetables and whole grains along with lean proteins like fish, chicken and turkey helps to create an environment that promotes the growth of probiotics.

In addition, the frequent use of antibiotics in our society can greatly disturb the probiotic flora in the gut. Although these antibiotics are intended to kill only the bad bacteria, they also affect the good ones. This is why many people experience diarrhea and yeast infections when they take antibiotics.

As the good probiotic bacteria are killed, bad (pathogenic) organisms like yeast are able to get a foothold in the system. Frequent or long term antibiotic use can dramatically alter the gut flora and can be a significant contributing factor to other long term health problems related to immune dysfunction and intestinal conditions.

Protecting the System

Probiotic bacteria are unique in that they do not cause infection and actually help to prevent infection from other aggressive micro-organisms related to food borne illnesses like salmonella and bacteria associated with traveler’s diarrhea. When healthy populations of probiotics are present in the large intestine, other bacteria that can potentially make us ill are crowded out, preventing them from causing a major infection. Without them we would be extremely susceptible to food borne infection.

The role of probiotics in immune function has been studied for decades. Scientists were curious as to why our bodies would strike up such a close relationship with these bugs. The most crucial role probiotics seem to play for humans is that of training the immune system. Most people don’t know that 60-70% of their immune system is located in the gut as a vast network of lymph tissue referred to as GALT (gut associated lymphatic tissue). The probiotics in our gut are constantly interfacing with the GALT and essentially priming the immune system for contact with other bacteria. They serve as a way for the body to learn how to respond to bacteria without actually having to suffer an infection. This becomes particularly important in young children whose immune system is in constant state of development until about age 7.

Due to the immune system’s essential role in allergies, probiotics are closely related to mediating certain allergy symptoms. Atopic dermatitis is an allergy related skin condition often affecting babies and young children. It is characterized by red, extremely itchy skin and is closely correlated to the development of asthma later in life. Probiotic supplementation to babies and children suffering from atopic dermatitis is very effective at reducing the symptoms and can often result in total resolution of the condition.

Foods like yogurt are made by using these probiotics (acidophilus and bifidobacterium species) to culture the dairy product. Some residual live organisms are left in the final product and these can help to support healthy bacterial levels in the gut. However, most store bought dairy products do not contain any live organisms by the time the product hits the shelves. For this reason, taking a high quality probiotic supplement is the best way to guarantee maximum health benefits.

Another great option for supporting optimal probiotic levels is to learn how to make your own cultured foods using acidophilus and bifidobacterium as the starter bacteria. Recipes for homemade yogurt, keifer, sauerkraut and other cultured vegetables are readily available. Acquiring probiotic organisms from food is the preferred method for the body.

Related Research

The Gut: Where Bacteria and Immune System Meet

The role of gut microbiota in immune homeostasis and autoimmunity