The immune system is pretty dang cool.

It's an extended network of proteins, organs, and cells that work synergistically to keep you protected, healthy, and thriving.

When your immune system is strong, microscopic battles are fought and won below your conscious awareness as you enjoy all of the opportunities that good health affords you. 

However, when your immune system is compromised, you get sick...and it sucks. 

And since good health and vitality are essential for an active, vibrant life, it's important to do what you can to support a strong immune system. 

This article will provide an overview of the human immune system, how it works, and what you can do to ensure yours is strong so you stay healthy.  

Why You Need an Immune System 

The immune system is not like a plumber or handyman that you occasionally call when you notice something has gone wrong or when a nasty bug is “going around." 

It’s working 24/7/365, actively fighting a number of different threats at any given time. That’s because humans are literally swimming in a sea of billions of pathogens, and they are swimming in us! 

Not all of these microorganisms are bad. In fact many of them are beneficial, symbiotic bacteria that can even support the immune system and promote good health.

So how does the immune system know the bad guys from the good guys, and most importantly, how does it defend against the bad guys? 

How the Immune System Works

The major organs of the immune system include the thymus, liver, bone marrow, tonsils, lymph nodes, spleen, and bloodall of which play a role in immune cell function.

Millions of immune cells flow through your lymphatic system and patrol your bloodstream, looking for atypical molecular structures of pathogens, which are called antigens.

Within minutes after a pathogen is detected, a protective immune response is coordinated. 

Specialized immune cells are sent into the bloodstream and attempt to destroy the pathogen by consuming it. 

While the pathogen is being destroyed, the immune cells on the front lines are communicating with the immune system at large, providing valuable information about the nature of the pathogen and how to best defeat it.

Soon after, a specialized set of immune cells are sent to locate and kill already infected cells.  

Meanwhile, other immune cells are busy manufacturing millions of antibodies, proteins that attach to a given pathogen’s antigens and destroy it. 

Why You Get Sick 

When you're healthy, and your immune system is strong, pathogens are eradicated within a few days without any noticeable symptoms. 

However—either because your immune system is compromised or the pathogen is novel and aggressive (or both)—your body is occasionally forced to go into overdrive from an infection, eliciting a stronger immune response.

This is when you get sick. 

At this stage, fever, inflammation, and other symptoms begin to manifest depending on the pathogen.  

These symptoms aren’t caused by the pathogen, they are actually natural processes designed to aid the immune response when the first line of attack is unsuccessful.

For example:

  • A fever or elevated body temperature creates conditions that slow the growth of bacteria and viruses. 
  • Inflammation is a form of cellular signaling that stimulates a stronger local immune response. 

In other words, symptoms like fever and inflammation are defensive strategies triggered by the immune system to up-regulate your body’s defenses.

Although it’s comforting to know that the painful and sometimes debilitating symptoms of infection are the battle cry of our immune system, most of us would rather get it over with like a silent assassin, killing all invaders quickly, quietly and discreetly. 

While the occasional illness or infection is often inevitable in our modern society, there is a lot you can do to ensure the frequency, duration, intensity, and overall disruption to your life is minimized.  

Natural Ways to Strengthen Your Immune System

In a nutshell, to strengthen your immune system, focus on incorporating lifestyle practices and essential nutrients that improve the function and formation of immune cells.

On the flip side, there are also foods, behaviors, and other factors that inhibit immune cells and weaken overall immune function. 

The following recommendations include simple dietary, supplement, and lifestyle tactics to support your immune system from the inside-out.

Focus on the Following Pillars of Good Health 

Strong immunity is a function of good health.

In other words, your immune system is only as strong as you are healthy. 

Therefore, focus on the following pillars of overall good health, and you'll do wonders for your immune system.

These health pillars include:

  1. Nutrition
  2. Sleep
  3. Stress Management

Here's a quick rundown on how each of these areas affect immune health.

1. Eat a Balanced, Nutrient-Dense, Whole Foods Diet

A lot of building occurs in the creation and maintenance of the various immune system organs, cells, and proteins. 

One of the best things you can do to support your immune system is provide an adequate supply of building materials in the form of micronutrients. This allows your immune system to build cells and proteins as needed. 

The best way to support your immune system with your diet is to get enough micronutrients from a whole foods diet, and shore up any deficiencies with supplements. 

A “whole foods diet” is simply a diet based on real, unprocessed foods close to their natural state. Whole foods will often have more nutrients, vitamins, and minerals than ultra-processed foods—and thus be beneficial for the immune system. 

To see if you’re getting enough of each micronutrient from your diet and where you might need to supplement, consider using a diet tracking app like Cronometer

For better immune function, you should also especially avoid or limit:

  • Alcohol
  • Refined sugar
  • Vegetable oils
  • Artificial sweeteners
  • Processed foods and carbohydrates

These “foods” have been shown to impair immune cell function, increase inflammation, and decrease your body’s natural defense response.

2. Get Enough Good Sleep

Your immune system loves the night shift.

Many essential processes that support the formation and function of immune cells occur while you sleep.¹

If being told to get more sleep “because it’s good for you” isn’t compelling, then consider what happens to your immune system when you don’t get enough sleep: 

  • A lack of sleep and poor sleep quality severely impairs immune function (slows activity and inhibits cellular reproduction) and increases susceptibility to infection.² ³
  • Even a single night of bad sleep can reduce immune cell activity by 70%.⁴

Researchers agree that a minimum of 7 hours of high quality sleep is required for optimal health and immune function. 

3. Avoid Chronic Stress 

While acute stress can up-regulate the immune system, chronic stress impairs immune function, increases susceptibility to infection, and extends the amount of time it takes to recover from illness.⁵

Chronic stress is also associated with a long list of other disorders and health problems including depression and anxiety and is a major contributor to poor sleep.

Moreover, finding ways to calm the nervous system while adopting new coping strategies can help increase overall health and improve immune system function. 

What About Supplements? 

Although a healthy diet, good sleep hygiene and effective stress management should be in the starting lineup of your immune health, there are certain supplements that can also play a supporting role. 

The supplements that may have the most science-backed effect on immune function include vitamin C, zinc, and vitamin D. 

Vitamin C

Vitamin C is an essential vitamin, meaning the body doesn’t produce it and it must be consumed in food or supplementation. It serves numerous functions and is linked to a wide range of impressive health benefits, most notably enhanced immune function. 

Supplementation of vitamin C has been shown to restore healthy plasma levels and improve general immune cell activity.⁶

Vitamin C also facilitates the production of immune cells and helps those cells function more effectively by protecting them from harmful molecules and oxidative stress.⁷

This is what qualifies vitamin C as a powerful antioxidant that supports the response of the immune system. 

Daily preventative doses up to 2 grams have been shown to have the greatest benefit on the strength and resiliency of the immune system.⁸


Like vitamin C, zinc is an essential nutrient and is present in every cell of your body.⁹ 

It plays a central role in immune cell formation and function and a zinc deficiency can lead to impaired immune system function.¹⁰

Although zinc deficiency is relatively uncommon, athletes, vegetarians, and the elderly are most at risk of being zinc deficient. ¹¹

The recommended daily dose for zinc can vary by individual. However, the upper limit is set at 40mg for the average adult.¹² Taking more than the recommended dose can lead to gastrointestinal distress and copper deficiency, so consult your doctor on the best dose for you.

Vitamin D, specifically D3, is another critical nutrient for the supporting the immune system. In fact, it's much more than a nutrient, and actually functions as a steroid hormone in the body!

Vitamin D activates the innate immune system, stimulates vital T-cells and natural killer cells, and inhibits the production of cytokines.¹³

You can get small amounts from foods such as fish, eggs, mushrooms, and vitamin D-fortified foods like cow’s milk, soy milk, and orange juice. But the best source of Vitamin D appears to be from sunlight.

Unfortunately, Vitamin D deficiency is extremely common. One study estimated that up to 41.6% of US adults are vitamin D deficient.¹⁴ This widespread deficiency is likely due to the majority of the population being indoors most of the day and not getting access to direct sunlight, as well as poor nutrition.

While regular sunlight exposure and a nutrient-rich diet are definitely recommended, sometimes lifestyle factors can keep you from getting the amount of Vitamin D a healthy immune system requires.

Luckily, supplementing with vitamin D3 is an effective and affordable way to support our immune system.

It's generally recommended that adults take up to 4,000 IU/day, but others may require more. We recommend discussing the appropriate dose for you with your doctor, potentially starting with a simple lab test to determine your current levels.

When shopping for a vitamin D supplement, consider one that also includes vitamin K2, which can provide greater immune support than vitamin D by itself and prevent complications of an imbalance of the two.¹⁵

Ki Points

The immune system is not so much a “thing” as it is a dynamic collaboration between your bodily systems, organs, and cells that work together to keep you healthy. 

When your immune system is strong, you can wake up each day feeling your best, most energized self. However, when your immune health isn't prioritized, your capacity to live a full and active life suffers.

If you need a little extra support, supplementing with essential nutrients like vitamin C, zinc, and vitamin D have been shown to be extremely effective for promoting optimal immune health.

Stay safe and healthy, friends!

Support your immune system naturally.

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