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Vitamin D And Immune Health

Vitamin D and immune health go hand in hand, as numerous studies have shown there is a clear correlation between your vitamin D levels and your immunity. The higher your vitamin D levels, the better your immune health will be. Given that this is fairly common knowledge, it should be safe to assume that people know to keep their vitamin D intake up, right?

Surprisingly, the answer to that is no, as studies show that around 50% of people have vitamin D levels below the optimal range, and 20% suffer from a vitamin D deficiency. If you find these numbers shocking, you aren’t alone, as we couldn’t believe it either.

Given the health implications that this can have, we felt it was our duty as health and fitness professionals to do something about it. That is why we have produced the following article dedicated to vitamin D and immune health. We will explain exactly what each is and how they are related, to hopefully give you all of the information you need to convince you to take better care of your vitamin D levels and immune health.

Table of Contents

What Is Vitamin D?

Vitamin D is an essential, fat-soluble vitamin that is also known as both cholecalciferol and “the sunshine vitamin”. It is vital in order for numerous functions in the human body to take place, and scientific studies have shown that the average person must consume a minimum of 10 to 20 mcg of vitamin D per day in order for their body to function at an optimal level and remain fully healthy (1).

Widely available in both foods and supplements, increasing your daily vitamin D intake offers a wide range of health benefits. This includes reducing the risk of influenza, improving bone, brain, heart, and immune system health and functions, boosting energy and testosterone production and levels, enhancing male sexual health, blood sugar levels, muscle strength, and bone density, and helping combat depression and many other health issues.

In this article, we are going to focus solely on how vitamin D can improve your immune health. For anyone who wants to learn more about any of the many other health benefits that vitamin D can offer, though, we have previously published two other articles that go over all of them in great depth, which you can read here and here.

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What Is Immune Health?

Immune health refers to the optimal functioning of the human immune system, which is a complex network of cells, tissues, and organs that work together to defend the human body against infections, diseases, and various other foreign invaders and harmful pathogens. A healthy immune system can effectively recognize and eliminate these pathogens while maintaining balance to avoid overreacting.

This is important, as an overreaction of the immune system can lead to chronic inflammation or the development of autoimmune conditions that are as bad or worse than the original issue. Good immune health is supported by adequate nutrition, regular physical activity, sufficient sleep, stress management, and overall lifestyle habits that help the body maintain resilience and recover from illness quickly and effectively.

Vitamin D And Immune Health: How Does Vitamin D Boost The Immune System?

Enhances Innate Immunity

Vitamin D activates numerous immune cells that are part of the innate immune system, such as macrophages and dendritic cells. The body’s first line of defense against viruses, flus, bacteria, fungi, and various other pathogens, this activation of the innate immune system promotes the production of antimicrobial peptides and proteins, such as cathelicidins and defensins.

These are a crucial part of the body’s defense system, as their potent antiviral properties enable them to help fight off and kill a wide variety of different infections, before they have a chance to do any damage to the body (2).

Modulates Adaptive Immunity

Vitamin D helps to balance the adaptive immune system, which provides a targeted response to specific pathogens. It does this by reducing the production of pro-inflammatory cytokines and promoting the production of anti-inflammatory ones, to help keep the immune response in check.

This enables it to regulate the production of T cells (especially helper and regulatory T cells) and B cells. These are vital for recognizing and attacking pathogens and helping the body fight off viruses, while preventing an overactivation that could lead to the development of an autoimmune disease (3).

Reduces Inflammation

Vitamin D is well-known to help reduce inflammation, which is an issue that frequently occurs when the immune system detects viruses, bacteria, flu, fungi, and many other pathogens. This is important as excessive levels of inflammation can lead to more severe symptoms and complications in people who have already started to become ill, while also making people far more susceptible to experiencing symptoms in the first place.

By modulating the body’s inflammatory response, vitamin D can lower the risk of you getting sick when pathogens like these enter your body. They can then even make the symptoms milder in the event that you do get sick too (4).

Learn more about Vitamin D and Inflammation here

Prevents Low Vitamin D Levels

Numerous studies show that people who suffer from low vitamin D levels are far more susceptible to both getting sick and developing more serious symptoms when they do. This can then also exacerbate many of the other issues that low vitamin D levels are known to cause, such as muscle and bone pain, weakness, tingling in the extremities, cramps, fatigue, and poor bone, joint, skin, and tooth health.

Some studies even indicate that vitamin D supplementation during flu season can help reduce the incidence of flu and other viral infections in most people. This is especially true in people who have low vitamin D levels or a vitamin D deficiency. This ability to stop the immune system from jumping into action all the time makes upping your daily vitamin D intake a great way to improve your immune health as a whole (5).