How Does the Immune System Work and How Can You Naturally Strengthen It?

Reviewed by Dr. Jonathan Bonnet, MD, MPH

The impacts of the COVID-19 global pandemic have been far reaching—loss, grief, and evolving uncertainty continue to affect Americans and individuals around the world. But since the virus’ emergence in March of 2020, another health topic has also garnered more attention: the immune system.

Among the threat of a contagious and dangerous respiratory virus, many have researched evidence- and non-evidence-based ways to boost their natural immunity. And now that safe and effective vaccines are available, more and more people are looking to understand exactly how the immune system works.

Here, we discuss the immune system’s role in the body, how it works, and which strategies may actually help to improve immunity.

What is my immune system?

The immune system plays a vital role in your body’s well-being. Like a shield protects a soldier in battle, the immune system works to protect your body from harmful substances, germs, and cell changes that could damage your health.

The main tasks of the immune system include:

  • Fighting against disease-causing germs (also called pathogens), like bacteria, viruses, parasites, or fungi and remove them from the body

  • Recognizing and neutralizing harmful substances from the environment

  • Fighting disease-causing changes in the body, like cancer cells

When the immune system recognizes something in the body that isn’t its own (also called antigens), it can trigger the immune system to start a whole series of processes to fight the unknown cells and protect the body. In some cases, the immune system attacks its own healthy cells thinking that they’re foreign cells, which is also known as an autoimmune response.

Importantly, there are two different subsystems that make up the immune system:

  • Innate immune system: Responsible for immediately fighting harmful substances and germs that enter the body using immune cells such as natural killer cells and phagocytes “eating cells.” This system produces what is called a nonspecific or innate immune response.

  • Adaptive immune system: Responsible for making antibodies to fight germs with which the immune system has already come into contact, also called an adaptive immune response. In this way, the adaptive response has the ability to manifest immune memory, which can help the body to enhance its immune response to fight off returning pathogens.

Are there signs and symptoms of a weak immune system?

When your immune system doesn’t function the way it should, it’s called an immune system disorder.

There are several possible causes of an immune system disorder:

  • Primary immune deficiency: When an individual is born with a weak immune system. Though rare, these are often diagnosed at a very young age and include conditions such as severe combined immunodeficiency (SCID).

  • Acquired immune deficiency: When an acquired disease weakens your immune system. An example of this is the Human Immunodeficiency Virus (HIV).

  • Overactive immune system: When your immune system is too active, sometimes as a result of an allergic reaction. Examples include anaphylaxis or reactions to specific substances, like peanuts or bee stings.

  • Autoimmune disease: When your system mistakenly attacks the body’s healthy cells. Examples include type 1 diabetes, rheumatoid arthritis (RA), multiple sclerosis (MS), inflammatory bowel disease (IBD), celiac disease, thyroid conditions, and more.

With more than 80 primary immunodeficiencies recognized by the World Health Organization and many possible immune disorders, the signs and symptoms of an immune system that’s not working as it should can be unique to its underlying cause.

However, some generalized signs of primary immunodeficiencies can include:

  • Recurrent infections (such as recurring sinus, ear, or bronchial infections)

  • Chronic gastrointestinal problems

Autoimmune disease symptoms can vary widely depending on the disease, but may include symptoms such as:

  • Fatigue

  • Joint pain

  • GI issues

  • Hair loss

  • Skin changes

If you’re concerned about the health of your immune system, reach out to your provider for personalized testing (Forfend can help with that).

Which factors can weaken the immune system?

Apart from a deficiency, disease, or disorder, there are several factors that can naturally depress the immune system:

  • Older age

  • Environmental toxins (including pollution and excessive alcohol)

  • Excess weight

  • Poor diet

  • Chronic stress

  • Inadequate Sleep

Can I have my immune system checked?

If your provider suspects a primary immunodeficiency, they may order initial laboratory testing, such as:

  • Complete blood cell counts (CBC) including a breakdown of the number and different types of cells.

  • Quantitative immunoglobulin measurements (IgG, IgM, IgA)

  • Measurements of functional antibodies against immunized antigens (i.e. Hepatitis B, C, HIV, autoimmune conditions such as thyroid disorders or celiac disease, etc.)

  • Delayed-type hypersensitivity skin tests

Additional specialty testing options include:

  • Total hemolytic complement assay (CH50)

  • Nitroblue tetrazolium test

(If you’re interested in specialty testing, reach out to your primary care provider or Forfend practitioner for guidance who can refer you to a specialist as needed.)

Other tests and indicators that may help to confirm or rule out a diagnosis of a weakened immune state or inflammatory state are:

  • Comprehensive metabolic panel

  • Erythrocyte sedimentation rate (ESR), which measures the quantity of red blood cells in relation to inflammation

  • C-reactive protein (CRP), an innate immune protein

  • Ferritin, a storage protein for iron whose synthesis is in part regulative by products of oxidative stress and elevated levels of which can indicate disease, inflammation, sepsis, or malignancy

How to improve the immune system

Scientists are continuing to explore the many factors that inhibit, alter, or impact immunity. As a result, there are several lifestyle modifications that may help to improve immunity:

  • Diet: Eating a varied diet with the right balance of nutrients will help to support the health of all cells, including immune cells. Though there isn’t a single magical food that you need to consume for immune protection, eating a diet rich in whole foods, fibers, vitamins, adequate proteins, and balanced fats and low in processed carbohydrates and meats will help to support optimal immune function. (Some evidence suggests that eating a diet containing probiotic and prebiotic foods may help as well.)

  • Managing Chronic Stress: Chronic stress elevates cortisol levels, which can increase inflammation in the body. Stress can also decrease the body's lymphocytes, or the white blood cells that help your immune system fight off infection. Finding a way to effectively manage stress can help you improve your mental and physical wellbeing while also supporting a stronger immune system.

  • Multivitamin supplements: If getting the right amount of vitamins and minerals from your diet isn’t always possible, a multivitamin may help to keep your immune system in optimal shape. Animal studies have found that deficiencies in zinc, selenium, copper, iron, folic acid, and vitamins A, B6, C, D and E can alter immune responses. Though eating a good quality diet is often enough to ensure adequate consumption of these nutrients, when not possible a general multivitamin with the recommended dietary allowances (RDA) may help.

  • Get good quality sleep: Though easier said than done, consistently getting enough sleep can help to bolster your immune system defenses, especially as you age.

Can lifestyle medicine help improve immunity?

Many of the pillars central to lifestyle medicine are also essential to supporting immunity, including nutrition, stress, sleep, movement, and substance use.

By replacing unhealthy behaviors with healthier ones, lifestyle medicine can help you to make habits that support a healthy immune system a part of your day-to-day life.

The bottom line

Our immune systems are a complex and vital support network for our body’s health and well-being. Understanding how your immune system may be affected by things like stress, nutrition, or poor sleep can help you find the right strategies for naturally boosting your immune defenses. If you’re unsure about where to start, Forfend can help. Our whole person wellness exams can help you optimize your approach to whole body wellness.


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