What is vitamin D and where do we get it from?
It has been estimated that approximately 20% of our vitamin D intake is through diet and the remainder (80%) is made by the skin following sun exposure. However this is an unusable form. First, it must pass through the liver (the main activation site) or the kidneys to become an active form of vitamin D. Diet is an important source of vitamin D for people with limited sun exposure. Certain foods are high in vitamin D – fatty fish (e.g. salmon, sardines and tuna), cod liver oil, egg yolks and fortified food products (e.g. cow’s milk, soya milk and breakfast cereals).
Does vitamin D impact our gut?
Vitamin D has been shown to have many important functions within the digestive tract:
Is there a relationship between vitamin D and IBS?
Research into vitamin D is steadily increasing for two main reasons.
Firstly, Vitamin D plays such a beneficial role in health and well-being.
Secondly, the rate of vitamin D deficiency is increasing.
It’s early days, and a lot more controlled research is needed – however it appears that there is a strong correlation between vitamin D status and IBS, both in adolescent and adult populations. But, what does this mean?
Can vitamin D help people with IBS?
One study looked at adolescents (aged 14 – 18 years) with IBS, who also had low amounts of vitamin D in their blood. These adolescents were divided into two groups – one group was given a high dose of vitamin D and the other group was given a placebo (dummy treatment), every day for six months. The researchers measured the levels of vitamin D in the participants’ blood before and after the study.
At the end of the study, the group who received the high daily dose of vitamin D had significantly higher levels of vitamin D in their blood in comparison to the placebo group. The participants with increased vitamin D had a significant improvement in IBS symptoms. Interestingly, this group also reported a reduction in the amount by which their IBS impacted the quality of their life.
What is the mechanism?
The exact mechanism of how vitamin D supplementation helps to improves IBS symptoms is unclear. However there is some research into the connection between vitamin D levels and depression, and it has been shown that supplementation can result in improvements in anxiety and depression. This could explain the positive impact that the vitamin D supplementation had on improving the quality of life of the patients.
Some patients with IBS present with a level of inflammation, albeit low, in their gut mucosa, which appears to play a role in symptom generation. Patients with diarrhea predominant IBS and post-infectious IBS (but not constipation predominant IBS) have been shown to have increased intestinal permeability, which is likely to be a result of low grade inflammation within the intestinal environment. Vitamin D has been shown to modulate the immune system by reducing inflammation by directly interacting with circulating immune cells but also by helping to maintain the intestinal barrier, preventing unnecessary immune system activation.
It looks promising!
There is strong potential for the use of vitamin D as a management strategy for IBS, however the benefits might not be universal. Nonetheless, the idea of such a low-cost but potentially effective solution for tackling risk factors associated with IBS is exciting.
Further research is needed but we are feeling hopeful.
What to do next?
Have you checked your vitamin D levels recently? Speak with your doctor if you have concerns about your vitamin D levels or before taking any supplements. Regular and safe sun exposure is an easy way to naturally boost your vitamin D levels, however, sun exposure comes with its own risks. Some parts of the world also don’t enjoy regular sunlight all year round (hello from Ireland!) so why not try incorporating some low FODMAP foods that are high in vitamin D into your diet? For example:
- Fatty fish (e.g. salmon, tuna, and mackerel)
- Cod liver oil
- Sardines
- Egg yolks
- Fortified foods (e.g. Tofu and cereals)
