July 2025
Karen Ensle EdD, RDN, FAND, CFCS
Rutgers Cooperative Extension of Union County
The immune system is a complex network of organs, cells and proteins that defends the body against infection. The immune system keeps a record of every microbe it has ever defeated so it can recognize and destroy the microbe quickly if it enters the body again. Some infections, like the flu and the common cold, need the body to react to it many times because many different viruses or strains can cause these illnesses. Catching a cold from one virus does not give you immunity against other viruses.
The body has several ways to defend itself including:
Your skin – a waterproof barrier that secretes oil with bacteria-killing properties.
Your lungs – the mucous in your lungs trapping foreign particles using small hairs called cilia, to move the mucous from your body as you cough.
Your digestive tract – the mucous lining contains antibodies, and the acid in your stomach can kill most microbes.
Your body fluids such as saliva and tears contain anti-bacterial enzymes that help reduce the risk of infection.
A rise in body temperature known as a fever, can kill some microbes and trigger the body's repair process. This process is called an immune system response.
Overactivity of the immune system can take many forms, including:
Allergic diseases – where the immune system makes an overly strong response to allergens. Allergic diseases are very common. They include allergies to foods, medications or stinging insects, anaphylaxis (life-threatening allergy), hay fever (allergic rhinitis), sinus disease, asthma, hives (urticaria), dermatitis, and eczema.
Autoimmune diseases – where the immune system mounts a response against normal components of the body. They include multiple sclerosis, autoimmune thyroid disease, type 1 diabetes, systemic lupus erythematosus, rheumatoid arthritis, systemic vasculitis.
Underactivity of the immune system, also called immunodeficiency, can be inherited – examples include primary immunodeficiency diseases such as common variable immunodeficiency (CVID), x-linked severe combined immunodeficiency (SCID) and complement deficiencies which arise as a result of medical treatment and can occur due to medications such as corticosteroids or chemotherapy or caused by another disease – such as HIV/AIDS or certain types of cancer.
A strong immune system can help you from getting sick and to recover quickly. Follow these suggestions to keep your immune system strong.
Remember to take small steps to keep your immune system healthy. Following these suggestions will make a huge impact on your overall health.