Many cells and organs work together to protect the body. White blood cells, also called leukocytes (LOO-kuh-sytes), play an important role in the immune system. Some types of white blood cells, called phagocytes (FAH-guh-sytes), chew up invading organisms. Others, called lymphocytes (LIM-fuh-sytes), help the body remember the invaders and destroy them.

One type of phagocyte is the neutrophil (NOO-truh-fil), which fights bacteria. When someone might have a bacterial infection, doctors may order a blood test to see what caused the body to have lots of neutrophils to confirm a bacterial infection. Other types of phagocytes do their own work to ensure that the body responds to invaders.

The two kinds of lymphocytes are B lymphocytes and T lymphocytes. Lymphocytes start out in the bone marrow and either stay there and mature into B cells or go to the thymus gland to mature into T cells. B lymphocytes are like the body’s intelligence system – they find their targets and send defenses to target them. T cells are your warriors – they destroy the invaders that the intelligence system finds.

Many cells work together. When the body senses foreign substances (called antigens), the immune system works to recognize the antigens and eliminate them.

B lymphocytes are triggered to make antibodies (also called immunoglobulins). These proteins lock onto specific antigens. After they are made, antibodies usually stay in our bodies in case we must fight the same germ again. That is why someone who gets sick with a disease, like chickenpox, usually will not get sick from the same disease again.

This is how immunizations (vaccines) prevent some diseases. An immunization introduces the body to an antigen in a way that does not make someone sick. Side effects are different, and commonly confused with illness. The side effects such as fever, muscle aches, fatigue, nausea, etc. from immunizations demonstrate that the immunization is working by creating an immune response. The vaccine helps the body make antibodies that will protect the person from future attack by the germ.

Although antibodies can recognize an antigen and lock onto it, they cannot destroy it without help. That is the job of helper T cells. They destroy antigens tagged by antibodies or cells that are infected or somehow changed. (Some T cells are called “killer cells.”) T cells also help signal other immune cells (like phagocytes) to go into action.

The first line of defense is to choose a healthy lifestyle. Every part of the body functions better when bolstered by healthy-living strategies. The following lifestyle behaviors have been proven to weaken the immune system.

1. Sedentary: Most people do not have a physically active lifestyle, which is one of the most important builders of the immune system. Regular moderate intensity exercise is beneficial for improving cardiovascular health, lowering blood pressure, and controlling body weight, all of which help to boost the immune system.
2. Diet/Obesity: We have gone from eating basic fruits, vegetables, nut, meats, eggs, fish, and whole grains to a diet full of ultra-processed foods, sugar, and other nutrient poor food which creates systemic low-grade inflammation. An unhealthy diet prevents people from getting the necessary micronutrients and Omega-3 fatty acids. This impairs the production and activity of immune cells and antibodies. A Western diet high in refined sugar and red meat and low in fruits and vegetables can also promote disturbances in the healthy intestinal microorganisms, resulting in chronic inflammation of the gut, and associated suppression of the immune system.

   Studies have also proven that excess body fat causes inflammation, which weakens the immune system. Most of those who had a severe illness from COVID-19, had excess body fat and/or a chronic metabolic condition. Today’s diet results in weight gain and a population in which over 50% of people are obese, super-obese and morbidly obese. Twenty-five percent of the population is overweight. As we age, the overweight/obese inflammation becomes worse. This makes people over age 60 have more inflammation of their gut.

3. Stress/Anxiety/Depression: Stress releases cortisol which normally is anti-inflammation However, chronic cortisol release is inflammatory and leads to weakening of the immune system.
4. Poor Sleep: Sleep is a time of restoration for the body, during which a type of chemical called cytokine is released that fights infection. Too little sleep lowers the number of cytokines and immune cells. Studies show that people who don’t get quality or enough sleep are more likely to get sick after being exposed to a virus. It can also affect how fast someone recovers if they do get sick.
5. Metabolic Disorders: Hypertension, diabetes, high cholesterol, and many other metabolic disorders cause inflammation, to which the immune system sends groups of cells to fight, thereby weakening the immune system.
6. Smoking: Smoking causes lung inflammation that demands cells from the immune system while creating excess secretions throughout the lungs, a perfect environment for pathogens.
7. Alcohol: Directly suppresses the immune system.