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How Vitamin D Regulates The Immune System

Supporting the immune system with vitamin D might be the best way to protect ourselves from a variety of harm.

04/12/19 By Purity Products 5 min read


It’s not easy to get all the vitamin D we need these days. Many of us spend hours upon hours indoors, working in an office under fluorescent lights, and when we do finally find ourselves outside, we are typically slathered in sunscreen out of fear of skin damage and diseases.

Article at a Glance
Vitamin D is hard to come by
  • A lack of sun exposure
  • Most foods we eat are not rich in vitamin D
  • A large portion of the population has some vitamin D deficiency
Vitamin D is closely associated with bone health
  • Vitamin D facilitates multiple biological processes, like calcium and phosphorus metabolism
  • There’s more to vitamin D than merely bone health
  • Vitamin D facilities properly functioning processes throughout the body, like bones, intestines, colon, brain, and immune cells
The Immune System
  • Your immune system prevents or limits infections
  • Healthy immune system cells seeks out invasive “problem” cells
  • A compromised immune system cannot fight infection
  • Overactive immune systems are problematic as well, causing autoimmune diseases
Vitamin D & the Immune System
  • Vitamin D triggers an array of beneficial processes in the immune system
  • Vitamin D modulates the production of antimicrobial peptides
  • Studies show that higher vitamin D levels equate to lower risk of infection and inflammation
Vitamin D & Autoimmune Disease
  • Studies suggest vitamin D-related treatments show potential for autoimmune disease management
  • Recommended Daily Allowances vary from institution to institution
  • Most agree that supplementation might be the ideal way to get vitamin D

This does not bode well for our relationship with the “sun vitamin.” In fact, research shows that vitamin D deficiency is perhaps the most common vitamin shortfall across a wide array of populations. Some studies estimate that about 1 billion people worldwide have insufficient levels of this vitamin, while one study in particular shows that 36 percent of adolescents and 57 percent of adults in the U.S. are lacking sufficient levels of vitamin D.

It doesn’t help that precious few foods we routinely consume are naturally rich in vitamin D. Unless you’re eating beef liver on a regular basis, and you probably are not, the main sources include things like fish oil and egg yolks—and these items truly only contain trace amounts of the vitamin. Then there’s foods fortified with Vitamin D, like milk, which unfortunately comes with a few health concerns of its own.
Our bodies definitely feel the widespread dearth of vitamin D. Studies demonstrate that vitamin D facilitates multiple biological processes, like calcium and phosphorus metabolism, neurogenesis, genome stability, and more.

Vitamin D: Beyond The Bones

And then there’s immune regulation. While most people know about the vitamin’s relationship to healthy bones through the synthesization of calcium, few immediately associate vitamin D with a healthy immune system. Maybe those milk commercials tying vitamin D to healthy bones worked a little too well.
In fact, vitamin D makes its way to multiple areas of the body after its absorbed. It shoots off to your bones, intestines, colon, brain, and immune cells, all of which have vitamin D receptors. Properly received vitamin D binds to those receptors and essentially flips a switch, turning on all of those processes and more.

What Is The Immune System?

The main thrust of our immune system is to prevent—or at the very least—limit infections. It is the gatekeeper to a constitutionally strong body. A healthy immune system does this by detecting unhealthy cells and targeting danger-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs). Immune system cells, which develop in the bone marrow, recognize these patterns and signals, and respond accordingly—hopefully ridding the body of the invasive condition.

But when the immune system is compromised, or is just not functioning properly, infections can take over and wreak serious havoc on your body. Then there are times when the immune system goes haywire, overreacting to a perceived threat or not shutting down when the threat has been sufficiently defeated. This is when allergic reactions arise and autoimmune diseases take hold.

The Role of Vitamin D in a Healthy Immune System

But how does vitamin D interact with the immune system and how does that interaction regulate your health and influence your wellbeing? When vitamin D is absorbed in the body and spread to various areas, it also finds its way to the cells of the immune system and once there, it triggers an array of actions.

For starters, vitamin D modulates the production of antimicrobial peptides—namely, cathelicidin, which serve a critical role in our innate immune defense against bacterial infection. And according to research, the vitamin D-cathelicidin connection has evolved over millions of years to efficiently promote healthy immune systems.

That study concluded that the ability of vitamin D to regulate anti-bacterial proteins, like cathelicidin, is so specifically important to humans that it is shared only by primates—and no other animal species. The researchers wrote in their conclusion that “the placement of the cathelicidin antimicrobial peptide gene under the regulation of the vitamin D pathway” maximizes the body’s immune response to pathogens while minimizing damage to the body.

In another study, researchers incubated human white blood cells with varying levels of vitamin D, then exposed them to a molecule associated with a bacteria that promotes inflammatory responses. The results of that study showed that cells incubated with no vitamin D showed higher levels of inflammation that the cells incubated with vitamin D.

The daily recommended dosage of vitamin D varies depending on the source. The Institute of Medicine places the recommended dietary allowance (RDA) for vitamin D at 600 international units (IU) per day for young adults and 800 IU per day for adults over 70. 

Vitamin D in the Fight Against Autoimmune Disease

In the cruelest of circumstances, there are about 100 diseases that are the result of our immune system attacking our own body’s organs, tissues, and cells. The physiological causes of these autoimmune diseases remains largely unknown, but many theories posit that a person’s genes combined with infections, environmental factors, and even stress can trigger the development of these diseases.

But what are we to do when our body’s natural defense system turns against us? While there currently is no cure for autoimmune diseases, recent studies suggest vitamin D-related treatments show potential for condition management. According to researchers, vitamin D promotes T-cells, which travel the body pinpointing outside invaders and differentiating them from harmless cells. This makes your immune system smarter, essentially training it not to attack itself.

How Much Vitamin D Should You Get?

The daily recommended dosage of vitamin D varies depending on the source. The Institute of Medicine places the recommended dietary allowance (RDA) for vitamin D at 600 international units (IU) per day for young adults and 800 IU per day for adults over 70. Meanwhile, the Endocrine Society recommends up to 1,500 to 2,000 IU of vitamin D for adults. The Mayo Clinic prefers the RDA of 800 IU.

Supplementing Vitamin D

With our immune systems constantly walking a fine line between protecting us from harm and actually inflicting damage upon us, we need to do all we can to support it. And since we are usually sitting in an office away from natural light or hiding from the negative effects of the sun—and our diets don’t deliver the vitamin D we need—supplementation might be our best chance to promote a healthy immune system.

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