Your immune system defends and protects your body from infection and damage from harmful pathogens on a daily basis. With a modern lifestyle the immune system is very easily weakened, which makes the body susceptible to a massive number of diseases. This means it is important to supply the immune system with the nutrients it needs to function properly. This article will explain the ways in which the immune system works, and how you can support your immune system through diet.
Innate immune system
The innate immune system is often referred to as the ‘front line of defense’, and is non-specific in its response to infection or damage, i.e it will respond the same way to different infections or foreign particles. It is the innate immune system which is responsible for mediating responses such as allergic reactions and inflammation, which, although are sometimes not desirable, aid with healing and protection. There are a number of cells which make up the innate immune system, and fulfill different roles and the production of these can can demand large amount of some nutrients. Some of the most important cells include:
Phagocytes- These cells produce toxic substances which kill pathogens and fungi in the body. They achieve this by engulfing the pathogen and producing harmful radicals, toxins and enzymes which break down the pathogen cell wall which destroys it. Examples of these chemicals are hydrogen peroxide, hydroxyl radicals, nitric oxides and various digestive enzymes. There are various sub-groups of phagocytes such as macrophages, dendrite cells, granulocytes which specialize in various roles and locations in the body. Dendrite cells play an important role in linking the innate and acquired immune system which will be discussed later.
A deficiency of vitamin B12, folate, selenium or copper are associated with a a low level of phagocytes in the body, which can result in an increase rate of infection throughout the body. Folate can be found high in dark leafy greens, whereas vitamin B12 and copper obtained from animal sources such as liver and eggs. Selenium is found in significant quantities in most nuts, but is most abundant in brazil nuts.
Mast cells – These cells are associated with mediating inflammation and allergic responses. When activated, mast cells release cytokines and histamines in response to damage or toxins (e.g a bee sting). This causes acute inflammation which stimulates rapid healing and an increased concentration in various immune cells at a target localized area. Mast cell deficiency is extremely rare, and is easily prevented by ensuring sufficient protein is present in the diet.
Natural killer T-cells – These cells do not destroy foreign cells, but destroy human cells which have become infected or compromised in some way. An example of this is a cell which is infected with a virus or a tumor cell, and destroying such cells will prevent infection spreading any further. Natural killer T-cells require a number of vitamins and mineral, but production of these cells is usually restricted by a lack of zinc and vitamin A, which are founds in seeds and vegetables respectively.
Adaptive immune system
The adaptive (or acquired) immune system compromises of highly specialized cells which target specific pathogens. When we take vaccinations we present weakened pathogens to our adaptive immune cells, which allows our body to prepare for future infections and respond quickly.
Lymphocytes – There are a number of types of lymphocytes in the body, and two of particular importance are memory cells and effector cells. Memory cells live for a long time, and store information on infections which the body has encountered in the past. This allows the body to respond rapidly to the same infection, and improve recovery.
Effector cells – These cells seek out and recognize pathogens, and mediate an appropriate immune response at a site of infection. This could include producing pathogen specific antibodies which neutralize the pathogens, or produce specific enzymes which breakdown the pathogen. Vitamin A, D and the mineral selenium are known to support the production and action of lymphocytes, and there is also emerging evidence that polyunsaturated fats (such as omega-3) are also important in maintaining lymphocyte cells aswell.
The immune system is a complex and diverse system, and requires a variety of nutrients to function properly. The innate immune system, which prevents the majority of pathogens infecting our body, is very dependent on zinc, selenium, copper, folate (vitamin B9) and cobalamin (vitmain b12). To ensure that you are obtaining enough of these nutrients it is important to consume nuts, leafy greens, bright colored vegetables (such as peppers) and seeds regularly.
The adaptive immune system, which targets specific pathogens and is responsible for fighting serious and established infections is heavily reliant on vitamin A, D and selenium to function effectively. These nutrients can be found in various vegetables, dairy and nuts.