Vitamin D may help boost immune function and reduce inflammation, which could benefit people living with ulcerative colitis. More research is needed to fully understand the link.

Vitamin D is a fat-soluble vitamin primarily knownTrusted Source for its beneficial effects on bone, brain, and immune health. Some research suggests it may also benefit people with ulcerative colitis.

Keep reading to learn more about how vitamin D may help support the management of ulcerative colitis symptoms.

Some research suggests that people with ulcerative colitis are more likelyTrusted Source to have low vitamin D levels due to several factors, such as malabsorption and inadequate dietary intake because of IBD symptoms.

Lower vitamin D levels have been linkedTrusted Source to a higher risk of disease development, severity, and complications like pancolitis.

As such, some researchers believeTrusted Source that vitamin D supplementation may be an effective, low cost treatment for ulcerative colitis.

However, it’s important to note that not all researchers agree.

For instance, the authors of a 2023 research reviewTrusted Source concluded that not enough high quality studies exist to support the use of vitamin D for ulcerative colitis.

Here’s how vitamin D may affect ulcerative colitis.

People with IBD are more likelyTrusted Source to have increased intestinal barrier permeability. This means your gut’s lining is compromised, allowing food and friendly gut bacteria to reach intestinal tissue.

This increases your immune system’s exposure to gut microbiota, which may lead to a heightened and abnormal immune response associated with inflammation and increased disease severity.

Vitamin D may help maintain intestinal barrier integrity by regulating proteins that could revert gaps in intestinal tissues.

Vitamin D may help improve and rebalance the gut microbiota, which may help reduce GI inflammation.

The microbiota of people with ulcerative colitis is more likelyTrusted Source to vary over time.

Vitamin D deficiency may also alter the microbial balance. For instance, it may increase the concentration of certain bacteria that could cause colon inflammation and reduce bacteria that may help relieve inflammation.

Research suggests that vitamin D may help inhibit multiple pro-inflammatory pathways.

It may helpTrusted Source reduce oxidative stress by regulating oxidative stress-reducing proteins, leading to reduced inflammation.

Vitamin D supplementation may also have positive effects on T cellsTrusted Source, a type of white blood cell that helps eliminate disease-causing microorganisms.

According to a 2022 review, T cells with low vitamin D levels promote higher concentrations of pro-inflammatory markers, grow more rapidly, and induce more severe colitis. In contrast, animal studies show that treating T cells with vitamin D slowed their growth, reducing inflammation.

Inflammation plays a fundamental roleTrusted Source in the development of colon cancer.

People with IBD have an increased risk of developing colitis-associated colon cancer, especiallyTrusted Source if they have vitamin D deficiency or if their inflammation is not well-managed.

Some animal studiesTrusted Source suggest higher vitamin D levels may help reduce the risk of colon cancer, but more research in humans is needed to fully understand the link between vitamin D, ulcerative colitis, and colon cancer.

Low vitamin D levels are linkedTrusted Source with increased disease severity and a higher risk of relapse. However, evidence on whether vitamin D supplementation benefits ulcerative colitis is mixed.

Some studies have foundTrusted Source that vitamin D supplementation may help reduce inflammation, disease activity, and symptoms, as well as increase remission rates.

However, vitamin D supplementation for IBD is challengingTrusted Source because impaired nutrient absorption requires higher doses, which may lead to vitamin D toxicity.

As such, more research on vitamin D supplementation for ulcerative colitis is needed.

According to the Food and Drug Administration (FDA), the recommended daily value (DV) of vitamin D is 20 mcgTrusted Source, or 800 International Units (IU).

However, you may need a higher dose if you have ulcerative colitis and have a vitamin D deficiency.

Research suggests that daily dosages of 2,000 IUTrusted Source may help improve symptoms and quality of life and are safe for people with mild deficiency.

Once sufficient vitamin D levels are reached, however, there’s no consensus on how much vitamin D is necessary to maintain them. Some people suggest that taking 1,000 IUTrusted Source per day is sufficient, but others note that people with severe deficiency require up to 4,000 IUTrusted Source daily.

You may want to talk with your doctor about how much vitamin D to take.

A note on choosing high quality supplements

While research suggests there are health benefits to taking vitamin D supplements, the FDA doesn’t monitor or regulate the quality of supplements in the same way that it regulates clinical medications.

Consider talking with your doctor before starting supplements.

Check out Healthline’s picks of the best Vitamin D supplements, vetted by our Medical Standards and Insights team.

Some research suggests that vitamin D may benefit gut health by improving immune response and reducing inflammation.

However, it’s important to remember that evidence on whether vitamin D supplementation is beneficial is mixed, and more research is needed. An adequate and safe dose is yet to be determined.

Consider speaking with your doctor before trying vitamin D to manage your symptoms.