Our bodies have natural barriers that protect us from infection. The skin, what we think of as a physical barrier, is a significant immunological barrier as well. That means that there are immune molecules in the skin that help fight off bacteria and other infectious agents.
From our time in the womb throughout childhood development, our bodies are learning how to tolerate certain substances and fight off others. Our immune system starts off with a genetic component and exposure to foods, bacteria and other agents helps shape it. As we grow, defense mechanisms in our gut and respiratory tract keep us healthy and free from infections. In an ideal situation, the body recognizes an infection that poses a threat and fights it off, while at the same time recognizes and allows bacteria in that are helpful to digestion. There is this ongoing monitoring – known as immune surveillance – that enables us to get rid of what is harmful and keep what is helpful.
Other barriers include the mucosal lining of the eyes, nose, mouth, respiratory tract and gastrointestinal tract. This is important because while protecting us from dangerous foreign substances in the environment, these barriers also have to let certain things in. After all, we have to breathe, take in nutrients, and drink diet sodas without our bodies trying to expel what is foreign to them.
The gut is a very important barrier. There are products on the market, such as yogurts, and supplements, that promise improved gut health by adding healthy bacteria to one’s diet. Commercial bias aside, the immune system is so complex that no one factor is guaranteed to be of benefit in every individual. Vitamin D, along with nutrition, a healthy lifestyle and one’s genetic makeup, all contribute to gut health.