Vitamin D regulates bone metabolism as well as immune system function. Recent research suggests that vitamin D deficiency may have an impact on the development of IBD, the severity of the disease, and whether or not the disease stays in remission.

How does vitamin D affect IBD?

Developing IBD

Results from several studies suggest that low vitamin D levels may be associated with the diagnosis of IBD. Here's an overview of what doctors have found:

  • In one large population study, researchers found high sun exposure to be associated with a significantly decreased incident risk of Crohn's Disease.
  • A longer term study saw women who had low levels of vitamin D had an increased risk of developing Crohn’s disease over the next 20 years.
  • Other studies have looked at people with a relatively new diagnosis of IBD and found that low vitamin D levels were very common among the individuals.
  • Several researchers have found that the incidence of Crohn's Disease increases as you get farther away from the equator, likely because of decreased duration and intensity of sunlight exposure.

Overall, these studies support the belief that sunlight exposure and higher vitamin D intake reduces the risk of IBD.

The severity of the disease

Patients with less sun exposure have also been found to have more serious cases of IBD. An increasing number of studies show that the severity of the symptoms experienced are linked with low vitamin D levels.

One study involving around 3000 patients with IBD compared vitamin D levels with future risk of surgery and hospitalizations showed a clear difference in people who had normal, insufficient, and deficient levels of vitamin D. The lower the level of vitamin D was, the higher the risk of surgery and hospitalizations.

Similarly, other studies have shown that people with higher levels of disease activity tend to be low in vitamin D, and the risk of surgery and hospitalization is higher in individuals who don't get enough vitamin D, compared to those that do. These studies suggest a connection between vitamin D levels and the risk of surgery and hospitalization for patients with IBD.

Keeping the disease in remission

Many studies have looked at whether vitamin D supplementation keeps Crohn’s disease in remission.

A Scandinavian study randomized people with Crohn’s disease in remission to receive vitamin D, or placebo. At the end of the year, they found that the individuals who had taken the vitamin D had lower rates of relapse compared to those who were on the placebo. The relapse rate for patients in the vitamin D treatment group was 13%, compared with 29% in patients who received a placebo, which indicates that vitamin D may play a role in preventing relapse.

Other studies that examined vitamin D levels during remission and have seen that there is a higher risk of relapse in patients with low vitamin D levels. In one study, patients who were in clinical remission with low vitamin D levels had a 25% greater risk of relapse over the next 12 months, even when they considered differences in endoscopic and histologic activity.

Other health benefits of vitamin D for IBD patients

Small studies have also supported that taking receiving enough vitamin D is not only associated with improvements in disease activity, but also other health-related quality of life.

Vitamin D can be considered a hormone that affects the immune system, which is responsible for managing how likely you are to get infections. Studies have suggested that vitamin D levels may be important in how patients respond to bacteria that causes diseases, and have linked low vitamin D levels with an increased risk of cancer (particularly colon cancer, where the risk is at least two times higher than the normal population), in people with IBD. It has also been shown that patients with low vitamin D levels tend to have a higher risk of Clostridium difficile (C. Diff. Colitis) infections.

Almost 50% of Crohn's patients will develop osteopenia, and 13% will progress to osteoporosis. The loss of bone mineral leads to osteoporosis and fractures, which may be avoided through early supplementation with vitamin D and calcium. When used together, the combination of vitamin D and calcium have been shown to have preventative benefits - including improved bone health and reduced fracture risk.

How do you get enough vitamin D?

Although a lack of vitamin D has been shown as a risk factor for autoimmune conditions like Crohn's disease, up to 70% of patients with Crohn's have a deficiency of vitamin D. You can obtain Vitamin D from two main sources:

1. Exposing your bare skin to sunlight (ultraviolet rays)
The part of the sun’s rays that is important is ultraviolet B (UVB). Large amounts of vitamin D are made in your skin when you expose your body to the sun. The anount of time needed to produce enough Vitamin D depends on a few factors such as where you live, the time of day, color of your skin (pale skins create vitamin D more quickly), and amount of skin exposed. It can take just 15 minutes for a very fair skinned individual, or more than a few hours for a dark skinned person.

2. Diet and supplements
Both sources of vitamin D, either through taking supplements or diet, are effective. Examples of foods that are high in Vitamin D include wild-caught fish, egg yolks, milk, and fortified breakfast cereals.

However, increasing dietary intake of vitamin D can sometimes be difficult, particularly in people with IBD who have food sensitivities and gastrointestinal intolerance to dairy products, which are high in vitamin D. Paired with the fact that there are not many foods which naturally contain vitamin D in large quantities, supplementation ends up being the default way many patients with IBD receive enough vitamin D.

What does this mean for you as an IBD patient?

There are many clinical studies that are starting to look at vitamin D as a therapeutic treatment in Crohn’s disease and ulcerative colitis. Some of these studies are evaluating the role of vitamin D in the bringing and maintaining remission for patients in combination other therapies, such as anti-TNF agents like Humira. These studies will help doctors understand the role of vitamin D, and guide their suggestions to patients who live with IBD.

As a patient with IBD, speaking with your physician and making sure you receive enough vitamin D every day may be able to help manage your symptoms and improve your general health.

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