For the immune system to work properly, two things must happen: first, the body must recognize that it is being threatened by foreign microorganisms. Second, the immune response must be activated quickly before many body tissue cells are destroyed by the invaders. 
In our environment, we are constantly exposed to viruses (such as those that cause colds and influenza), bacteria (such as those that cause pneumonia and food poisoning), parasites, and fungi. In a healthy individual, the immune system is efficient in the removal of these harmful organisms. However, when the immune system is overworked or weak due to chronic stress, poor nutrition or exposed to chemical/environmental toxicities (i.e. smoke, herbicides, pesticides), it is less effective at removing toxic & mutated cells, or harmful pathogens. The resulting consequences can be severe, leading to the development of chronic illnesses that can be debilitating.
Chronic illnesses can result from a hypo-functioning of the immune system or a hyper-functioning of the immune system. In other words, while the human body is always attempting to maintain a level of homeostasis, an imbalance can result in either of two types of immune disorders: immunodeficiency diseases occur as a result of a weakened immune function (i.e. HIV), while autoimmune conditions occur when the cells of the body’s own immune system attacks healthy cells (ie. rheumatoid arthritis or systemic lupus erythematosus). In order to appreciate the role of the immune system in the development of chronic illness, we must first understand the basic fundamentals of this system. The immune system is comprised of various organs, cells and chemical messengers that seek out and destroy invading micro-organisms. This system provides the human body with protection against various micro-organisms that cause disease.
In general, the immune system can be viewed as a network that protects us from pathogens that are determined to be invaders. More specifically, the body’s immune system is able to discriminate between beneficial “nonself” invaders (food or helpful bacteria) versus threatening invaders.
In order to prevent the onset of an acute illness or the development of chronic conditions, we can be more disease resistant by making healthier dietary choices, changing certain lifestyle habits, and using various natural health products to boost and maintain a healthy immune function. For example, adopting simple lifestyle modifications such as drinking 1.5 litres of water and eating 4-5 small meals per day, maintaining a healthy weight, ensuring adequate sleep and making time to rest during the day, as well as regular exercise at least 3-4 times per week are all beneficial for the immune system.
