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Vitamin D And Immune Function

How Does Vitamin D Boost Immune Function

Vitamin D Reduces Autoimmune Diseases: New Research

The immune system is an incredibly complex protective mechanism, but to simplify, we can divide the immune system into two main categories: innate immunity, and adaptive immunity.

Innate immunity is our nonspecific defense mechanism that activates in the presence of an invading pathogen. So, even if you have never been exposed to a virus or pathogen, your body has a built-in ability to protect itself from an invader. This part of your immune system is your first line of defense against any type of new type of germswhether it is bacteria, viruses, and fungi. And its super important to be sure this line of defense is strong.

The other type of immune response is your adaptive immune response. This immune response is active against pathogens that you have previously encountered. The body recognizes, adapts and attacks specific invaders much more efficiently.

In the case of brand new types of influenza strains, the body has not had a chance to develop specific antibodies against it yet. So, this is where we call in the powers of our innate immune system to protect us. Vitamin D works to strengthen this innate immune system response.

Many different studies have associated vitamin D with its power to fight infection. One report looked at almost 19,000 people and found that the individuals with the lower levels of vitamin D were more likely to report upper respiratory tract infections, than those with sufficient levels of vitamin D.

Vitamin D And Immune Health

Research shows that vitamin D plays an important role in immune function, and a deficiency in it is shown to increase your susceptibility to infection. “Some studies have shown that vitamin D deficiency is even associated with greater risk of self-reported upper respiratory tract infections,” Tolentino says. Further, “low serum levels of calcidiol are also associated with higher susceptibility to infections like tuberculosis, influenza, and viral infections of the upper respiratory tract,” Tolentino says.

One of the main functions of vitamin D is to help activate T cells, aka the “killer cells” in the body. T cells actually detect and destroy foreign pathogens — like viruses. “That makes vitamin D especially crucial for maintaining a functioning immune system that’s capable of fighting back foreign pathogens,” Tolentino says.

It’s important to know that although the coronavirus does affect the respiratory system, researchers and doctors know little about how vitamin D affects your risk of catching COVID-19 at this time. The best ways to reduce your risk of being infected with the coronavirus is to follow CDC and WHO guidelines, what your local officials say and to take care of your health as much as you can overall. Vitamin D is known to help the immune system, which is promising for protecting you from many different types of illness.

Exposing your skin to the sun is one way to get vitamin D.

What Can Happen If You Are Deficient In Vitamin D

Vitamin D deficiencies can mean your immune system is more vulnerable, but there are some other important conditions to know about too.

“Severe vitamin D deficiency can lead to a condition called rickets in children, and osteomalacia in adults. Osteomalacia is the softening and weakening of bones, and symptoms include joint and bone pain, muscle weakness, difficulty walking and bones that are easily fractured,” Tolentino says.

Another connection that scientists are researching is the link between mood disorders and vitamin D deficiency. Many studies have looked at depression risk specifically, like this one that found a link between vitamin D deficiency and risk for depression in older adults. In another study, adults with depression were given vitamin D supplementation and it did help improve symptoms in many of them.

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Role Of Vitamin D In Immune System Regulation

The primary role of vitamin D is the regulation of bone mineral homeostasis however, its importance in the regulation of the immune system has emerged in the last 30 years. In 1983 it was demonstrated that macrophages were involved in vitamin D production and that VDR were isolated in activated human inflammatory cells,. In 1984, Rigby, et al found that vitamin D may inhibit T cell proliferation. Evidence grew of the role of vitamin D in the regulation of the immune system.

It has been shown that the enzyme 1-alpha-hydroxylase is present not only in renal tissues but also in activated macrophages and dendritic cells,, even if PTH inhibition has been seen only in renal tissues. In murine macrophages, 1-alpha-hydroxylase may be regulated by other mediators, such as IFN-.

Regarding B cell regulation, 1,252D3 is involved in the suppression of immunoglobulin production and B cell proliferation and differentiation. Because patients with systemic lupus erythematosus , particularly those with antinuclear autoantibodies and amplified disease activity, had reduced 1,252D3 levels, suggesting that vitamin D might be involved in the regulation of autoantibody expression, Chen, et al studied the effects of 1,252D3 on B cells from patients with SLE. That study showed that 1,252D3 has a direct effect on B cells, including an inhibitory effect on proliferation, on generation of class-switched memory B cells, on plasma cell differentiation, and on immunoglobulin production.

Signs Of Deficiency And Toxicity

Figure 1 from Vitamin D and immune function: an overview.


Vitamin D deficiency may occur from a lack in the diet, poor absorption, or having a metabolic need for higher amounts. If one is not eating enough vitamin D and does not receive enough ultraviolet sun exposure over an extended period , a deficiency may arise. People who cannot tolerate or do not eat milk, eggs, and fish, such as those with a lactose intolerance or who follow a vegan diet, are at higher risk for a deficiency. Other people at high risk of vitamin D deficiency include:

  • People with inflammatory bowel disease or other conditions that disrupt the normal digestion of fat. Vitamin D is a fat-soluble vitamin that depends on the guts ability to absorb dietary fat.
  • People who are obese tend to have lower blood vitamin D levels. Vitamin D accumulates in excess fat tissues but is not easily available for use by the body when needed. Higher doses of vitamin D supplementation may be needed to achieve a desirable blood level. Conversely, blood levels of vitamin D rise when obese people lose weight.
  • People who have undergone gastric bypass surgery, which typically removes the upper part of the small intestine where vitamin D is absorbed.

Conditions resulting from prolonged vitamin D deficiency:


Symptoms of toxicity:

  • Weight loss
  • Irregular heart beat
  • Hardening of blood vessels and tissues due to increased blood levels of calcium, potentially leading to damage of the heart and kidneys

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Risks Of Getting Too Much Vitamin D

If you take excessive amounts of vitamin D supplements, you may get too much of it. However, this is unlikely to happen through diet or sun exposure because your body regulates the amount of vitamin D produced through sun exposure.

Vitamin D toxicity can lead to an increase in your blood calcium levels. This can result in a variety of health issues, such as (

Vitamin D And Granulocyte Biology

In the early 2000s, a physiological role for the VDR in neutrophils was investigated by using differential display analysis to identify expression of genes in 1,25D-treated, LPS-stimulated neutrophils. Of the genes identified, the neutrophil elastase inhibitor trappin-2/elafin/SKALP was potently induced in LPS-exposed neutrophils, but was mildly suppressed by 1,25D. Under the same conditions, IL-1β was slightly inhibited by the active hormone. Since then, a few other studies have delved into the role of vitamin D in neutrophil innate immunity. Among those was one that found increased apoptosis in neutrophils from patients with chronic obstructive pulmonary disease treated with 1,25D. This is noteworthy because COPD pathogenesis is characterized by a lower rate of neutrophil apoptosis, and vitamin D acquired the capacity to counter this via activation of p38 MAPK. Furthermore, 1,25D treatment enhanced the production of IL-8 in LPS-exposed neutrophils however, no effect was detected on the phagocytic capacity of the cells when challenged with E. coli.

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Safety Of Supplementation In Humans

Recommendations from national health authorities for optimal serum 25D levels differ in many countries . Currently, no international consensus is available on the optimal level for vitamin D supplementation, in particular on the safe upper level. While the tolerable upper daily limit given by the Endocrine Society is 10,000 IU , the more conservative Institute of Medicine considers a supplementation of up to 4000 IU/day to be safe . The European Food and Safety Authority currently recommends to stay below 4000 IU/day .

Administration of the highly active metabolite calcitriol is limited because of potential side effects, in particular hypercalcemia. Active vitamin D or its analogs are rarely required except in advanced chronic kidney disease and very few other indications such as hypoparathyroidism and pseudohypoparathyroidism. The most common forms of inactive vitamin D used for supplementation are cholecalciferol and ergocalciferol , shown in Table 1. While in a recent meta-analysis vitamin D3 has been found to be more efficacious in improving 25D status, especially when given as loading doses , both forms are considered to have an excellent safety profile including a broad therapeutic window .

Vitamin D And T Cells

Vitamin D and immune defense against flu, COVID-19

Although primarily an activator of the innate immune system to enhance immediate response to infection, vitamin D acts to regulate activity of the adaptive immune system. Consistently, low levels of circulating serum 25D have been correlated with increased risk of developing T-cell-mediated autoimmune diseases such as MS, T1DM, IBD, systemic lupus erythematous , and rheumatoid arthritis . These associations may also correlate with exposure to UV light However, despite these observations and the well-described direct and indirect effects of 1,25D on T cells as detailed below, therapeutic use of vitamin D in supplementation trials has so far shown only modest effects. There remains a need to better understand the mechanisms of 1,25D-mediated immunomodulation to improve treatment of autoimmune inflammatory disease.

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Looking For A Vitamin D Supplement

We did the research for you. See Healthlines picks for the 13 best vitamin D supplements.

Several factors can affect your ability to get adequate vitamin D from sunlight alone.

You may be less likely to absorb enough vitamin D from the sun if you (

  • severe bone or muscle pain or weakness
  • stress fractures, especially in your legs, pelvis, and hips

A healthcare professional can diagnose a vitamin D deficiency by performing a simple blood test. If you have a deficiency, your doctor may order X-rays to check the strength of your bones.

If you receive a diagnosis of vitamin D deficiency, a healthcare professional will likely recommend that you take vitamin D supplements. If you have a severe deficiency, they may instead recommend high dose vitamin D tablets or liquids.

You should also make sure to get vitamin D through sunlight and the foods you eat.

Can Vitamin D Lower Your Risk Of Covid

Vitamin D is a fat-soluble vitamin that plays a number of critical roles in your body.

This nutrient is especially important for immune system health, leaving many people wondering whether supplementing with vitamin D may help reduce the risk of contracting the new coronavirus that causes COVID-19.

While theres currently no cure for COVID-19, preventive measures like physical distancing and proper hygiene can protect you from contracting the virus.

Also, some research shows that having healthy levels of vitamin D can help keep your immune system healthy and may protect against respiratory illnesses in general.

A recent study indicated that patients hospitalized with COVID-19 who had sufficient levels of vitamin D had a decreased risk for adverse outcomes and death .

This article explains how vitamin D affects immune health and how supplementing with this nutrient may help protect against respiratory conditions.

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Pulmonary Immune Defense Mechanisms And Their Regulation By Vitamin D Signaling

The respiratory tract has a large surface area in contact with the environment. Thus it provides a major site for invasion by pathogenic organisms, against which it must defend. The defense mechanism is comprised of both innate and adaptive immunity. Activation of the innate immune system drives activation of the long term adaptive immune system . The principal cells involved are the airway epithelia, alveolar macrophages, and dendritic cells . All of these cells express CYP27B1, the enzyme producing 1,252D, the active metabolite of vitamin D, as well as the vitamin D receptor . Expression of CYP27B1 is constitutive in airway epithelial cells , although it can be further increased by some types of viral infection . The 1,252D produced by these cells promotes alveolar epithelial cell proliferation and reduces their apoptosis after an inflammatory challenge . Deletion of VDR from these cells leads to loss of integrity of the epithelium . On the other hand CYP27B1 is induced in alveolar macrophages by toll like receptor ligands for TLR1/2 , interferon , and LPS , and in DC by TNF, IFN, polyI:C, and LPS . Moreover, these cells all express pattern recognition receptors of which TLRs are a major component and by which viral RNAs are recognized .

How Vitamin D Affects The Immune System

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Scientists have uncovered fresh insights into how vitamin D affects the immune system and might influence susceptibility to diseases such as multiple sclerosis.

Vitamin D is produced by the body in response to sunlight and is often lauded for its health benefits. Researchers found it also affects key cells of the immune system.

This discovery might explain how vitamin D regulates immune reactions that have been implicated in autoimmune diseases such as Multiple Sclerosis.

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Evidence For Regulation By 125d Of Antibacterial Innate Immunity In Vivo In Humans

Crohns disease arises from defective intestinal innate immunity, and vitamin D deficiency is common in patients with CD . Several small clinical studies have been published providing evidence that vitamin D supplementation may be beneficial for patients with CD. These have recently been reanalyzed in two meta-analyses. From their survey of 18 randomized clinical trials, Li et al. found decreased relapse rates in CD patients treated with vitamin D relative to controls . Similarily, a systematic review demonstrated low 25D status is associated with increased odds of inflammatory bowel disease activity, mucosal inflammation, low quality of life and subsequent clinical relapse in CD patients . These observations are likely to be reinforced in the future as additional findings continue to be published . Recently, in a Korean cohort of IBD patients including those with CD, severe vitamin D deficiency was linked to an aggressive disease course and increased risk of surgical intervention . These findings are of interest, because inactivating NOD2 mutations frequent in Western patients with CD are not found in affected Koreans . Other work in post-operative CD patients found that higher vitamin D levels were associated with lower risk of recurrence as measured by endoscopy . Collectively, although it is not yet routine practice , these studies argue that vitamin D supplementation should be a part of a treatment plan for patients with CD.

Vitamin D Helps The Immune System During Cold And Flu Season

Vitamin D helps the immune system stay balanced, much like a gymnist walking a balance beam.

Vitamin D helps our immune systems stay balanced during the cold and flu season, and serve as a pharmacy resource.

There are Vitamin D receptors and activating enzymes on the surfaces of all White Blood Cells. The role that vitamin D plays in keeping the immune system healthy is very complex because the immune system has to be perfectly balanced. If there is too much stimulation, autoimmune diseases can set in. If there is not enough immune system activity, frequent infections can occur.

Low levels of vitamin D have been linked with both extremes, and low levels of vitamin D have been associated with worsening autoimmune diseases. Low levels of vitamin D are not the underlying cause of the autoimmune disease, but low levels of vitamin D can make autoimmune disease states worse.1

Low levels of vitamin D have also been associated with frequent infections. In 2009, the National Institute of Health warned that low vitamin D levels are associated with frequent colds and influenza.2

And so it appears that vitamin D helps keep the immune system balanced much like a gymnast walking on a balance beam.

Since the NIH announcement, there have been many studies to determine the best regimen of vitamin D supplementation and to better understand this association.


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  • Affiliations: Department of Therapeutic Radiology and Oncology, The 306th Hospital of PLA, ChaoYang, Beijing 100101, P.R. China, Center for Special Medicine and Experimental Research, The 306th Hospital of PLA, ChaoYang, Beijing 100101, P.R. China
  • Pages: 120-124
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    Vitamin D is an essential fat-soluble vitamin withmultiple functions. The main source of vitamin D is transformedfrom 7-dehydrocholesterol after exploration with ultravioletirradiation and sequential hydroxylation into 25D and an activehormone, 1,25-dihydroxy-vitamin D3, by hydroxylases in the kidneyand liver. It can also be absorbed from dietary intake or oralsupplements. It has been shown that vitamin D receptor ishighly expressed in the intestine, kidney, thyroid and bone. Previous findings showed thatseveral types of immune cells such as T lymphocytes, monocytes,macrophages, and dendritic cells express VDR as well. The activeform of vitamin D exerts its effects on these tissues by binding toVDR. In addition, some studies present that macrophages, dendriticcells and lymphocytes also express vitamin D activating enzyme,1–hydroxylase . Therefore, except for the classicalphysiological function of regulation of calcium and bonemetabolism, vitamin D may also have immunomodulatory effects.

    Materials and methods

    Animal studies
    Proliferation assay ofsplenocytes
    Quantification for IL-2production
    Flow cytometric analysis of cellmarkers of CD4 and CD8



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