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Can Vitamin D Help Protect Against Inflammation & Autoimmunity?

Written by | Last updated:
Puya Yazdi
Medically reviewed by
Puya Yazdi, MD | Written by | Last updated:

Many people are turning to vitamin D supplements and sun exposure in an attempt to bring their inflammatory and autoimmune issues under control. Research confirms that healthy vitamin D levels are important for keeping inflammation at bay. Read on to understand whether vitamin D can protect against autoimmune problems and excess inflammation.

Snapshot of Vitamin D for Inflammation & Autoimmunity

  • Reduces inflammation (strong evidence)
  • Deficiency linked with chronic inflammation and autoimmune disorders
  • May improve symptoms of allergic diseases like eczema and asthma (moderate evidence)
  • May improve some symptoms of autoimmune disorders (limited evidence)

The body naturally makes vitamin D when exposed to sunlight. Getting regular, moderate sun exposure is a safe way to maintain normal vitamin D levels during the summer months.

Vitamin D is also found in certain foods, such as fatty fish like salmon and sardines. Additionally, many vitamin D supplements are available on the market.

Taken at the recommended doses, vitamin D supplements are considered safe. However, taking too much can be harmful. Vitamin D supplements may also interact with prescription medications. Remember to talk to your doctor before supplementing!

Vitamin D helps reduce inflammation in the body. Some studies suggest it might also improve allergies and autoimmunity. Make sure you get enough of this vitamin through sun exposure and food.

Vitamin D As a Natural Anti-Inflammatory

1) Balances the Immune System

Studies have shown potent effects of vitamin D on both innate and adaptive immunity. It has the potential to influence a wide range of immune imbalances, infectious and autoimmune diseases [1, 2].

Cells involved in innate and adaptive immune responses (macrophages, dendritic cells, T cells and B cells) have receptors for vitamin D [3, 4].

Effects of vitamin D on the immune system include:

  • Inhibits B cell production and antibody secretion [5, 6]
  • Decreases T cell growth, inhibits T cell activation and IL-2 production [7, 8]
  • May shift a Th1 to a Th2 phenotype [9, 3]
  • Regulates the activity of monocytes/macrophages [10, 11]
  • Inhibits dendritic cells production and growth [10, 11]
  • Decreases the secretion of inflammatory cytokines IL-1, IL-2, IL-6, IL-8, IL-17, TNF-α, IFN-γ, and IL-12 [12, 8, 13, 14]
  • Increases anti-inflammatory cytokines IL-10 and IL-4 [15, 13, 16, 17]
  • Inhibits the production of IgE by B cells and enhances the production of IL-10 by dendritic cells and T cells, playing an important role in allergic immune responses [13, 16]
  • Reduces the expression of MHC class II, CD40, CD80, and CD86 [8, 13]
  • Decreases TGF-beta (contributes to tissue repair by promoting tissue fibrosis) (18, 19, 20, 21)
  • Crucial for T Cell activation [22]
  • Regulates differentiation of CD4+ T cells (decreases Th1 and Th17 cell production, and increases Th2 and Treg cell production) [17, 9]
  • Increases CD8+ T Cells, important in controlling viruses, intracellular bacteria, and cancer [23, 24]
  • Increases Natural Killer T Cells [25]
  • Releases antimicrobials in response to an infection such as cathelicidin and beta-defensin 4 [26, 27]

All in all, these findings suggest that vitamin D helps maintain a healthy immune response. It reduces inflammatory messengers and increases anti-inflammatory ones.

Vitamin D’s potential to increase Tregs may be especially important since Tregs are immune cells that prevent the immune system from getting out of control. These cells work to prevent both allergic and autoimmune tendencies [28].

Next, let’s take a look at various autoimmune and inflammatory conditions and whether vitamin D can affect them.

Experimental research suggests that by balancing the immune response, vitamin D helps prevent excess inflammation and autoimmunity.

Vitamin D & Autoimmune Disorders

2) Might Be Beneficial in Multiple Sclerosis

Despite some promising findings, there is insufficient evidence to rate the safety and effectiveness of vitamin D in multiple sclerosis

Higher vitamin D blood levels may be protective against developing multiple sclerosis (MS), according to some researchers. In one study on women, each 10 nmol/L increase in blood vitamin levels was associated with a 20% decreased the risk of multiple sclerosis [29, 30, 31].

Also, higher vitamin D levels were associated with a reduced worsening and recurrence of multiple sclerosis symptoms. In a study, each 10 nmol/l increase resulted in up to a 12% reduction in recurrence [32, 33]. Additional large-scale studies are needed to confirm these findings.

According to another study, optimal blood concentrations of this vitamin may reduce disease-related complications (including increased bone degradation, fractures, and muscle weakness) [34].

One group of researchers found that increased sun exposure during ages 6 – 15 years was associated with a decreased risk of multiple sclerosis. Similarly, outdoor activities were associated with a reduced multiple sclerosis risk [35, 36].

Having these findings in mind, some scientists believe that multiple sclerosis occurs less often in people who are likely to have high vitamin D blood levels, as those living in sunny climates, at high altitudes, and areas with a diet rich in fish oils that contain this vitamin [37].

Additionally, vitamin D has an anti-inflammatory action, which can be beneficial in multiple sclerosis. It decreases the secretion of inflammatory cytokines and results in a shift from a Th1 to a Th2 phenotype. The Th1 phenotype tends to be more common in people with autoimmunity [38, 39].

However, it is important to remember that the above evidence isn’t conclusive. Vitamin D supplementation in people with MS appears to be safe, but at high doses, it can lead to changes in calcium levels. More research is needed to determine whether it’s truly beneficial [40, 41].

Studies suggest MS is less common in people with higher vitamin D levels. Maintaining higher levels might also reduce disease recurrence. However, evidence is lacking to recommend supplementation in people with MS.

3) Might Help with Psoriasis

According to some studies, vitamin D levels are significantly lower in patients with psoriasis [42, 43].

In one pilot study, a high daily vitamin D dose of 35,000 IU was safe and effective for psoriasis patients. However, this study only included 25 patients. High-quality, large-scale studies need to replicate these findings before we can draw any conclusions from them [44].

Creams and lotions with synthetic vitamin D analogues (calcipotriol and/or tacalcitol) are considered first-line treatment for mild-to-moderate psoriasis. These treatments are sometimes taken in combination with other systemic therapies in more severe cases of the disease [45, 46].

It’s important to remember that studies show that topical applications are beneficial but the data on oral supplementation is mixed [47, 48].

Creams with vitamin D analogues improve psoriasis symptoms. No solid evidence supports oral supplementation, though it shows some promise. More research is needed.

4) Deficiency in Autoimmune Thyroid Conditions

Vitamin D deficiency is associated with autoimmune thyroid disease [49, 50].

Deficiency is common in patients with Graves’ disease. It may exacerbate the onset and/or development of Graves’ disease and is associated with an increased size of the thyroid gland [51, 52].

Correction of the deficiency may be able to reverse it [49].

Vitamin insufficiency is associated with Hashimoto’s thyroiditis [53, 54].

Vitamin D deficiency severity was associated with the duration of the disease, thyroid gland size, and antibody levels [55].

Vitamin D deficiency has been linked with autoimmune thyroid problems. The benefits of supplementing are still uncertain.

5) Plays a Role in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) activity is associated with lower vitamin D blood levels [56].

However, there is insufficient evidence to support supplementation in people with lupus. 

Approximately 65% of the patients with SLE had vitamin D blood levels < 30 ng/mL [57, 58].

Limited research suggests that vitamin D supplementation has an effect on the immune system in patients with SLE. It decreases memory B cells, effector Th1 and Th17 cells, and increases Tregs [59].

People with lupus are commonly deficient in vitamin D, though the benefits of supplementation have yet to be determined.

6) Rheumatoid Arthritis

Early findings are promising, but there is still insufficient evidence to determine the safety and effectiveness of supplementation in people with rheumatoid arthritis. 

Vitamin D supplementation suppresses Th17 cell cytokines and has the effect potential to improve symptoms in patients with rheumatoid arthritis (RA) [14].

According to some estimates, vitamin D deficiency is present in 30-63% of people with rheumatoid arthritis [60].

Greater intake of vitamin D may be associated with a lower risk of rheumatoid arthritis in older women [61].

Other researchers have associated low vitamin D blood levels with rheumatoid arthritis symptoms and severity. Some believe that supplementation is beneficial for people this disease, though this remains controversial [60, 62].

In one study, 500 IU/day of vitamin D along with anti-rheumatic therapy improved pain relief in patients with early rheumatoid arthritis [63].

Large clinical studies are needed to determine the efficacy of vitamin D supplementation (alone or as an add-on) in people with rheumatoid arthritis

Despite promising early results, more research is required to confirm the benefits of vitamin D for people with rheumatoid arthritis.

Vitamin D & Chronic Inflammatory Disorders

7) Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is chronic inflammation of the gut that includes Crohn’s disease and ulcerative colitis.

Vitamin D supplementation may have a beneficial role in IBD, but there’s insufficient evidence to determine their effectiveness [64, 65].

Studies in mice indicate that this vitamin plays a crucial role in this disease [66].

Vitamin D may have an anti-inflammatory effect in patients with IBD. Oral supplementation increased blood vitamin D levels and reduced blood TNF-α levels (protein playing a large role in the gut inflammation) [67, 65].

One study showed a 32% decrease in CRP (C-reactive protein) levels and a 46% decrease in ESR (erythrocyte sedimentation rate) in patients receiving vitamin D [68].

1200 IU/d vitamin D supplementation reduced the recurrence of Crohn’s disease from 29% to 13% [68].

Low vitamin D level is associated with a higher risk of polyps and adenomas in the colon, common complications of ulcerous colitis [69].

Vitamin D may reduce inflammation people with IBD, though additional studies would be beneficial to confirm its effects.

8) Affects Chronic Obstructive Pulmonary Disease

Despite some scientific interest, proper data to back up vitamin D supplementation in COPD patients is lacking. 

Studies highlight that vitamin D deficiency is common in patients with chronic obstructive pulmonary disease (COPD) and correlates with the severity of the disease [70, 71].

Lower blood vitamin levels were also associated with a higher risk of COPD [72].

Its deficiency is associated with an increased risk of lung infections, causing worsening of COPD (73).

Vitamin D regulates airway contraction and inflammation [74].

It is also associated with bone mineral density and exercise performance in patients with COPD [75, 76].

However, some studies showed no benefit of vitamin D supplementation on COPD symptoms and severity [77, 78].

People with COPD tend to have low vitamin D levels and a tendency to catch respiratory infections. However, evidence is lacking to support supplementation.

9) Risk of Type 1 Diabetes

Vitamin D plays a role in insulin production and secretion from pancreatic cells. However, there’s not enough evidence to determine whether supplementation can protect against type 1 diabetes disease development [79].

Its deficiency leads to impaired glucose and insulin secretion, and increased risk of type 1 and type 2 diabetes mellitus [80, 81, 82, 83, 84, 85, 86].

Studies show that supplementation with this vitamin restored insulin secretion [87, 83, 88, 89].

Vitamin D deficiency in early life predisposes to the later development of type 1 diabetes and its complications [90, 91].

A study found that an intake of 2,000 IU of this vitamin during the first year of life diminished the risk of developing type 1 diabetes (92).

The Diabetes Autoimmunity Study in the Young (DAISY) reported an increased presence of antibodies against pancreatic cells in newborns of mothers with a low intake of this vitamin during pregnancy [93].

Vitamin D deficiency might impair sugar control and increase diabetes risk. Supplementation might have a protective effect, though the evidence is far from conclusive.

10) Celiac Disease

Almost 60% of patients with celiac disease were found to be vitamin D deficient or insufficient [94].

11) Plays a Role in Cystic Fibrosis

Low blood vitamin D levels are commonly found in patients with cystic fibrosis (CF).

Deficiency occurs in 25 – 33% of patients with late-stage CF [95].

Absorption of this vitamin is reduced in patients with CF due to insufficient pancreatic enzymes [96].

Also, CF patients have increased oxidant and P450 activity, which could lead to faster degradation of vitamin D [96].

95% of cystic fibrosis patients required 1,800 IU/day of vitamin D to achieve blood concentration above 25 ng/ml [97].

Vitamin D deficiency is common in people with cystic fibrosis, who also absorb less and break down more of this vitamin. Higher-dose supplementation may be beneficial if recommended by a doctor.

Caution: Effects on Sarcoidosis

Vitamin D is produced by macrophages in sarcoid granulomas causing increased blood calcium levels [98, 99, 100].

An increased level of this vitamin is associated with disease activity [101].

Elevated vitamin levels require chronic immunosuppressive therapy in patients with sarcoidosis [102].

Patients with sarcoidosis do not benefit from vitamin D supplementation [103].

People with sarcoidosis should avoid vitamin D supplementation unless recommended by a doctor.

Vitamin D & Allergies

12) Eczema

Atopic dermatitis (eczema) affects up to 20% of children and up to 3% of adults [104].

However, it’s unknown if vitamin D supplements are beneficial in people with eczema. 

Some scientists believe that vitamin D supplementation may improve disease symptoms and severity. It is also considered as a safe and tolerable therapy when used at the recommended doses [105, 106].

However, concerns have been raised that giving vitamin D to babies and children may increase the risk of atopic conditions like eczema. 

Further research is needed to clarify these associations.  

In cell-based studies, vitamin D increased the production of cathelicidin, an antimicrobial deficient in atopic dermatitis. More studies are needed to explore its mechanism of action and efficacy [107, 108].

People with eczema are commonly deficient in vitamin D. Supplementation may improve some symptoms, according to limited research.

13) Asthma Severity

Evidence on the benefits of vitamin D supplements for reducing the severity of asthma has been conflicting. 

Vitamin D deficiency is associated with increased asthma symptoms and severity [109, 110].

Its deficiency causes decreased lung function [111, 112, 113].

Lower vitamin levels are associated with increased markers of allergy and asthma severity [110].

Studies showed that higher vitamin D intake by pregnant mothers reduces the risk of asthma by 40% in children 3 to 5 years old [109, 110, 114].

Vitamin D enhances the anti-inflammatory effects of corticosteroid therapy in asthma [115, 116].

Limited evidence suggests that higher vitamin D levels reduce inflammation in asthma, while people who are deficient are prone to asthma symptoms. No studies back up supplementation in people with asthma, though.


While a growing body of evidence seems to indicate that vitamin D might play a role in a myriad of medical conditions, most of the evidence for these roles comes from in vitro, animal, and epidemiological studies. Randomized clinical trials are considered to be more definitive [117, 118].

In conclusion, make sure to talk with your doctor about the risks and benefits of supplementing with vitamin D, especially if you suffer from an inflammatory or autoimmune condition.

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