5 Nutrients You Need for a Healthy Immune System

People are looking for immune-supportive nutrients now, more than ever. 

Google searches for “vitamin D,” “vitamin C,” “vitamin A,” and “immunity” are at an all-time high. (1)

With the flood of misinformation on the internet, how do you know what you really need to support a healthy immune system?

Your body’s immune system needs very specific nutrients every day to keep it running correctly, and to ensure a healthy response. Every day we encounter pathogens (yeasts, viruses, and bacteria), stress, and toxicity that can quickly burn through our nutrient stores. In fact, many individuals are deficient in these immune support nutrients because they are not able to get the necessary amounts from diet alone. (2)

You know how important a healthy diet is for overall wellness. But are you getting enough of the necessary nutrients that specifically target fighting infection?

In this article, we’ll cover five very specific nutrients that are critical to keep your body’s immune system functioning at top notch. These nutrients don’t just fight off bacteria and pathogens as you might think; they do something else that might surprise you. (3)

Your Immune System: Friend or Foe?

Your immune system is an extremely complex, multifactorial system, composed of different cells, tissues, and compounds that work synergistically together to protect your body. The immune system is like a surveying system in your body, that is constantly monitoring and checking things out, trying to identify “self” from “non-self.” (4) We are lucky to have a built-in defense system, ready for an attack at any moment! 

As this surveying is happening, all day every day, it identifies its own “self” (your body cells), which pose no threat. But when your immune system comes across a “non-self” (infection or invasive pathogen), it ramps up the immune response – quickly. The immune response to an invading pathogen consists of antimicrobial compounds and inflammation, including heat, pain, swelling, redness, and even loss of function. And this “ramping up” is not specific to one area – but is fully encompassing. (3, 4)

This is where you might be surprised – it’s not solely the invaders that can cause damage, it’s primarily your own body’s immune response.

For example, when you get sick, you may get a fever, which raises your entire body temperature.

But when you have an immune response, your body isn’t just killing off the invaders. Large portions of your body are involved, and tissues are often damaged in the process.

In addition to this inflammatory response, antimicrobial compounds are also secreted by your immune cells. These damaging compounds, such as hydrogen peroxide, can kill infections and pathogens. You might have purchased hydrogen peroxide in the brown bottle from your local grocery store to disinfect a cut. But did you know your body also makes it during the immune response? It does this to “disinfect” itself. While hydrogen peroxide is damaging to pathogens, it’s also damaging to you. If not regularly neutralized and cleaned up, these harmful compounds can cause further issues and slow the healing process of an illness. This process of increasing harmful compounds in the body is known as oxidative stress, and it’s a byproduct of activating your immune system. Oxidative stress creates an internal environment that requires antioxidants to neutralize the oxidative chemicals. (5)

Here’s another example. When you hurt your ankle, it usually swells. And what do you do? You ice it – to cool the temperature, which slows the pace of your immune cells and lowers inflammation, thereby speeding up healing processes.

It may seem strange to think that your immune system responses can harm your own body. However, it’s a concept that is crucial to understanding why we need to ensure adequate nutrition that is actually counteracting the powerful effects of your body’s immune response.

5 Important Nutrients for Immune System Health

When thinking about the nutrients you need to “support a healthy immune system,” we want nutrients that can help quench inflammation and oxidative stress – natural things that occur as a result of your own body’s immune response. Dr. Ben Lynch has extensively researched the best nutrients for immune health and has identified five specific nutrients needed in sufficient amounts to kill infection, deactivate the immune response, restore, and repair your body. These include nutrients with properties that are anti-inflammatory, antioxidative, and antimicrobial to help you to overcome the immune response. (6) Dr. Lynch recommends these five nutrients to his patients who need immune system support.

1. Vitamin D

If you had to choose a single vitamin to support your immunity and immune system response, it should be vitamin D. Vitamin D supports immunity through multiple pathways, and most notably, by triggering antimicrobial immune cells to fight against invading pathogens. (7) Think of it as your antimicrobial activator.

It does this by enhancing the production of something called defensin β-2 and cathelicidin antimicrobial peptides (CAMP), which are peptides that can protect the body from microbes, either directly, or indirectly. These peptides have been shown to increase the body’s resistance to respiratory pathogens, and protect against potential GI pathogens (acting as a barrier response). They can kill invasive microbes simply by destruction of the membrane. Antimicrobial peptides like these are essential to preventing infection and increasing healing processes from sicknesses, and vitamin D is a crucial trigger for their production. (7,8,9) In diseases and infections such as Crohn’s disease and Helicobacter pylori, infection of the stomach has been associated with low levels of cathelicidins. (9)

But the antimicrobial effects are just the beginning. 

Vitamin D can also help to moderate the inflammatory response and tissue damage during an immune response. (10) Researchers have determined vitamin D to be an important immune system modulator, meaning it can turn off the immune response when necessary. (7) Having sufficient vitamin D in your system is shown to reduce the risk of infections, whereas vitamin D deficiency is associated with acute respiratory distress syndrome. (11, 12)

Vitamin D plays some critical roles in our immune health! Yet, vitamin D deficiency is common. (13) Eighty percent of vitamin D is obtained through your skin from the sun (UVB exposure). (7) But many individuals protect their skin from the sun. This can contribute to deficiency in vitamin D and related deficiency diseases. Aside from low skin-to-sun exposure, other factors of vitamin D deficiency include a poor diet low in oily fish, and vitamin D-related gene polymorphisms. (13)

Except for during summer months, the skin makes little if any vitamin D from the sun at latitudes above or below 37 degrees of the equator. People living in these areas are at greater risk for vitamin D deficiency. Even though cereals, juices, and other foods are sometimes “fortified,” processed foods often contain inferior forms of nutrients. For example, it’s important to ensure the type of vitamin D you are getting is D3, and not D2. D2 is an inferior form and is not well utilized by the body. (14)

This vitamin is so important for immune system health that if you were to take anything to support your immune system, vitamin D should be at the top of your list. The best way to know if you’re deficient is to have your qualified healthcare professional test your serum levels of 25-hydroxy vitamin D. They will be able to recommend the best way for you to raise your vitamin D levels based on your lab results.

2. Vitamin C

Vitamin C is easily one of the most researched vitamins. It plays multiple roles in immune system function, much attributed to its role as a powerful antioxidant. Recall the definition of oxidation: damaging compounds produced by your body to fight infection or in response to chronic inflammation. Antioxidants, as the name suggests, literally help to neutralize oxidative byproducts called “free radicals” to prevent damage and premature aging. (15)

Supplementation with vitamin C has been shown to support the immune system’s response to pathogens. And it appears that benefit arises when supplementation is dosed higher than the RDI and in the first 24 hours of the onset of a cold. (16,17) 

Vitamin C can stimulate certain immune cells, such as white blood cells. And, when combined with zinc, vitamin C shows its ability to support GI and respiratory health. (18)

Glutathione, known as our body’s “master antioxidant”, is increased in white blood cells during vitamin C supplementation. Glutathione is essential for controlling inflammation and oxidative damage in the body. (19, 20)

Vitamin C is found naturally in citrus fruits, such as grapefruit, and vegetables, such as bell peppers. In fact, bell peppers are one of the richest sources of vitamin C! However, during sickness, we use high amounts of this nutrient, and therefore our need for it rises dramatically. This is why additional vitamin C may be helpful.

3. Vitamin A

As a nutrient, vitamin A is incredible for respiratory health and the ability to fight infection. Also known as retinol, this essential fat-soluble nutrient helps the body to maintain strong inner and outer barriers, including skin, eye, lung, nasal passages, gastrointestinal, and genitourinary tracts. These barriers can be considered the “walls” of our body to prevent pathogens from entering. In fact, supplementation with vitamin A has been shown to maintain healthy gut lining barrier function when measuring indicators of gut permeability. (21,22)

Vitamin A plays a big role in lung and respiratory health. The membranes of the respiratory tract and lungs are extremely important parts of the immune system. They act as physical barriers to prevent the inhalation of pathogens. It has been shown that in the midst of vitamin A deficiency, children were more susceptible to acute respiratory tract infections and diarrhea. (23) Vitamin A has been shown to support a healthy lung response during illness, and deficiency is common in those with tuberculosis. (24, 25)

You may have heard that vitamin A can be found in foods like sweet potatoes and other brightly-colored fruits and vegetables. However, it’s important to realize that the form of vitamin A found in plants (beta-carotene) is not an active, usable form of vitamin A. 

It is critical to get vitamin A in its active form, called retinol. Why? Because not everyone can adequately convert the inactive form found in fruits and vegetables (beta-carotene) into the active form (retinol). One of the enzymes responsible for converting beta-carotene into retinol in the liver is called beta-carotene oxygenase 1 (BCO1). (26) 

Certain gene variations, or SNPs, in the BCO1 gene, may slow down your BCO1 enzymes and reduce this conversion, leading to lower vitamin A utilization. Even without SNPs, your body has to work much harder to convert beta-carotene into its active retinol form. 

Consuming vitamin A as retinyl palmitate, an active form of vitamin A found in certain supplements, is a way to bypass this enzymatic conversion and get the best utilization of vitamin A in the body. 

4. Vitamin K

Vitamin K is an incredible vitamin for managing blood flow and blood vessel health. It is also a perfect addition to vitamin D supplementation, as both vitamin D and K have synergistic effects when it comes to cardiovascular health and bone health (calcium regulation). Vitamin K helps to alleviate any potential increase in long-term side effects such as calcification in arteries and weak bones, by helping certain proteins bind to calcium. (27)

Vitamin K also activates matrix GLa protein (MGP) which protects against damage to lungs and blood vessels. Those that experience lung infections show vitamin K deficiency markers, and have poor outcomes of respiratory health. (28, 29)

[Graphic adapted from Reference #29]

Especially when combined with vitamin D, vitamin K has the potential to support blood vessels and lung health during infection, such as severe acute respiratory infection. This is due to vitamin K’s role in blood anti-clotting factors and activation of proteins in the veins that prevent blood clotting. (28, 29)

Vitamin K, as you can see, does so much more than support calcium utilization, but rather has a large impact on the immune system related to blood coagulation and respiratory health. 

Why K2? 

There are two natural forms of vitamin K: K1 (from green leafy vegetables and plant oils) and K2 (from animal products and bacteria in the GI tract). Vitamin K2 specifically has been shown to inhibit inflammatory signaling cells and is superior in its ability to support the calcium regulation in blood vessels. (30)

5. Zinc

Zinc is an essential mineral. You may have seen it in the common “zinc lozenge” often used to support throat and respiratory health. It is true, zinc deficiency is highly correlated with respiratory tract infections. And supplementing with zinc in a lozenge format consistently has been shown to support a healthy immune system when responding to illness. (31)

Zinc is highly involved in the immune system as a “communication nutrient.” It helps keep inflammation at bay by playing a role in inflammatory signaling. It also affects the activity of immune cells called macrophages, which help to kill off pathogens. Zinc also functions as an antioxidant, helping to limit the oxidative stress damage caused by your immune system response. (32, 33) This mineral is so highly involved in the immune system, you will want to ensure that you always have enough in times of need!

The Bottom Line

A healthy immune system does more than simply fight off bacteria and other pathogens; it also includes the ability to stop the signaling and fighting mechanisms when appropriate (like oxidation and inflammation) to prevent damage to your cells. Yes, fighting infection is critical to protection. But putting down the ammunition and turning off the immune response is just as important to healing and preventing damage to our own cells. 

There are specific nutrients that support the entirety of this system, including normal immunity (defense mechanisms), inflammatory responses, and oxidative stress responses. These five nutrients include vitamins A, C, D, K, and zinc. Each of these are not only essential for overall health, but are crucial for a normal immune response, respiratory and lung health, and healthy oxidative stress response. Because getting enough of these nutrients from your diet is rare, you may want to talk to your qualified healthcare provider about supplementing with these five immune-supportive nutrients.