It’s no secret there are bugs out to get us. Viruses, bacteria and other pathogens can invade and cause harm to our body resulting in disease and illness. Because of this, our body has developed a system of defense against these invaders, known as our immune system.
How does it work?
When healthy, our immune system is able to determine which cells belong to us and which ones are invaders. When a potential pathogen is detected, your immune system will attack and either kill or decrease the amount of harm it can do [1].
Our immune system is broken down into two parts, innate and adaptive. Our innate immune system provides a general response to fight off foreign cells. It’s attack is non-specific; it responds the same to any potential pathogen that enters our system. Our innate immune system works quickly, generating a response within 0-4 days but mainly relies on our skin, mucus membranes and immune cells for their fight [2].
Our adaptive immune system takes a more specific approach. Our bodies are complex, they are able to learn from exposure and adapt. When we are exposed to a virus, bacteria, parasite or other potentially harmful organism, our body will learn about it and work to create antibodies to further protect against future attacks. Our adaptive immune system is what we rely on to remember previous pathogens we have come in contact with so that we are stronger when we encounter them again [2].
Because our adaptive immune system needs to identify the cell first, it takes a little longer than our innate immune system to kick, about 4-7 days before a significant response is noted however, it will work faster once it comes in contact with the same pathogen in the future. Our innate immune system is why some diseases we only get once in our life, such as the Chickenpox. This part of our immune system is made up of T and B lymphocytes as well as antibodies in our blood [2].
Unfortunately, our immune system is not immune to faults. If not healthy, it is unable to work properly to defend against these pathogens. Sometimes your immune system will even attack itself as a result of certain conditions such as allergies or autoimmune diseases [1].
Parts of the Immune System
Our immune system is made up of many different parts, all working together with a common goal; to protect our health. Let’s take a deeper look into some of the more specific parts of our immune system.
Skin and Mucous Membranes
Our body’s first line of defense is the physical barrier that separates and helps to block off any incoming pathogens from entering our body. This is composed of our skin and mucus membranes, the key components of our innate immune system. Our mucus membranes are lined with mucosal fluid and can secrete protective chemicals such as anti-microbial peptides [2].
Probiotics
Probiotics are the microscopic organisms that live in our gut, known as healthy bacteria or “good bugs.” Recent studies have shown there is a strong relationship between probiotics and our immune function, specifically with our innate immune health but they have been shown to help regulate adaptive immune responses as well. They do this by moderating the functions of our immune cells, such as T and B lymphocytes [4].
The most commonly studied strains include Lactobacillus, Bifidobacterium and Saccharomyces. These organisms help our mucosal defense systems to fight off pathogens by producing destructive substances and blocking them from adhering to our intestinal wall by stealing their spot [5].
Because of the strong relationship between probiotics and immune function, diet plays a key role in our ability to support our immune system. Probiotics rely on the foods we eat to flourish in our gut. If we do not provide adequate nourishment for these good bacteria to thrive, our digestive system, as well as our immunity, will take a huge hit.
White Blood Cells
Our white blood cells act as army against harmful cells in our body and are a key part of our immune system. These cells circulate our blood stream and reside within various parts of our body waiting to be needed. There are many different types of these white blood cells, all playing different roles in our immune function [1].
T and B cells are both types of white blood cells known as lymphocytes. They are made from stem cells in our bone marrow and are responsible for triggering an immune response. B cells are named because they are made in bone marrow. While T cells are also made in the bone marrow, they travel and mature in the thymus which is why they are called T cells. Most of these T cells will then travel to and inhabit our lymph nodes. These white blood cells will move to the site of infection to fight, sometimes called killer T cells. Our B cells do not move to the site of infection, instead they work to help create antibodies to protect against future attacks from the same pathogen. An antibody is simply a protein made by our immune system that will attach itself to foreign cells and help to remove them from the body.
Lymphatic System
Our lymphatic system is made up of small glands and organs throughout our body that help to filter, contain and destroy harmful cells [1]. You may have heard or noticed your lymph nodes. These are small glands located all over our body that work to subdue the spread of potential pathogens. This is why you might notice your lymph nodes in common areas such as your throat will swell up when you have a cold, this means those T cells in your lymph nodes are fighting to contain and destroy that infection.
Our Lymphatic system is made up of primary and secondary organs. Our primary lymphatic organs include our bone marrow and the thymus and they function to create and mature lymphocytes which are the cells needed to fight off these pathogens. Our secondary organs include our lymph nodes, spleen, tonsils and mucus membranes. These are the organs responsible for the actual attack on harmful cells [3].
The Impact of Diet on Our Immunity
It shouldn’t be surprising that our diet will have a significant effect on our immune system. When we eat, food travels through the hollow organs that make up our digestive tract. These organs, lined with mucus membranes, are loaded with millions of bacteria and other micro-organisms both beneficial and potentially harmful, known as probiotics. These micro-organisms play a role in the digestion and absorption of nutrients. When we have a hearty community of healthy bacteria in our gut, our body is able to function at it’s best to stave off disease and illness. As mentioned earlier, in order to have this, we must ensure we are providing these bacteria with the nutrients they needs to flourish [6].
Unfortunately, there is no strict definition for gut health other than being free from disease or illness. Our intestinal microbiota, a.k.a. our gut flora determines our overall gut health. These live organisms are responsible for protecting our gut and promoting the functions of our digestive tract, regulating our metabolism and regulating our mucosal immune system. Our gut health plays a huge role in our immune function, in fact, over 75% of our immune system is made up of our gut flora [6].
We can help to keep our gut healthy by taking in nutrients, such as probiotic and prebiotic foods that help with nourishing our microbiota. Probiotics are the good bugs that benefit our gut while prebiotics are what feeds the probiotics.
Both Prebiotics and probiotics are available in supplement form but they are actually quite easy get through diet alone. Good sources of probiotics include your fermented foods such as sauerkraut, miso, kimchi and fermented dairy products such as yogurt or kefir. Good sources of prebiotics include a lot of your fruits, vegetables and whole grains such as bananas, artichokes, onions, garlic and beans [7].
Prebiotics are mainly composed of indigestible fiber. If you are uncertain if you are getting enough fiber in your diet, the recommended range for the average adult is between 25-38 grams per day. Unfortunately the average American gets only about 15 grams a day [8]. When increasing fiber in your diet, be sure to do it gradually to avoid any stomach discomfort. It is also recommended to increase your fluid intake as well when consuming more fiber.
As you might have guessed, your best bet for getting adequate nutrients for gut health is to consume a balanced diet with a variety of fruits, vegetables, whole grains, lean meats and dairy products. Be sure to avoid or limit highly processed foods, fried foods, alcohol and sugar sweetened beverages in your diet. If you don’t like a lot of the foods mentioned above a supplement may benefit you.
When choosing a probiotic supplement be sure to choose a one that has a variety of microbes to get the most bang for your buck. You also want to make sure you get a good number of microbes from that supplement so it’s important to choose one that has colony forming units (CFU) in the billions. CFU is what tells you just how many microbes are actually present in that supplement.
In the end, we have a lot more control than most of us know when it comes to promoting and maintaining the health of our immune system. No one likes getting sick which should be more of a reason to pay closer attention to the foods you are choosing to nourish yourself with.
