Vitamin D and IBS

Research shows low vitamin D levels are associated with IBS

Originally published on: June 10th, 2022. Last modified on June 16th, 2022

Many people living with irritable bowel syndrome are vitamin D deficient, according to a study published in the BMJ Open Gastroenterology1. It has since been found that 82% of IBS sufferers are also low in vitamin D (less than 20 ng/mL)2 so naturally we come to question if there is a link between vitamin D and IBS symptoms. The University of Sheffield has been spearheading this important area of research.

Before we continue, let’s revisit these two key elements:

Irritable bowel syndrome (IBS) is a chronic and debilitating functional disorder of the gastrointestinal (GI) tract, affecting over 10% of people in the UK, costing the NHS in excess £11 million per year.

Vitamin D, affectionately known as the ‘Sunshine Vitamin’ is an essential fat-soluble vitamin for the absorption of calcium5 and which the body generates when exposed to sunshine, or from eating a diet rich in oily fish, egg yolks and red meat.

According to the NHS, our bodies need 10 micrograms of vitamin D a day as part of a healthy diet and lifestyle. It can be tempting to take a vitamin supplement however there are risks associated with the supplement such as Vitamin D Toxicity, so make sure you consult your doctor first1.

IBS and Vitamin D deficiency

Why and how IBS develops is something of a mystery, although dietary factors and stress are known to make symptoms worse. 

Symptoms include a combination of diarrhoea or constipation, bloating, urgency (the need to use a restroom in a hurry), white or yellow mucus in the stool and the sensation of incompletely passing stools.

These can cause embarrassment for patients, who may live with the condition undiagnosed. There is no cure, and the triggers and effects of IBS vary from one individual to another, which means that finding an effective treatment can be difficult.

Can Vitamin D help reduce IBS symptoms?

A study carried out in 2021 in collaboration with Sheffield Teaching Hospitals NHS Foundation Trust4 assessed whether vitamin D supplements could reduce the severity of IBS symptoms, and in turn improve quality of life for patients.

The study concluded that vitamin D supplements do not ease symptoms of IBS, but did confirm that a vitamin D deficiency remains widespread amongst people living with IBS which could potentially lead to an increased risk of fractures and osteoporosis in the long-term. 

Regular supplements of Vitamin D did help to increase levels in patients, the benefits of which contribute to wider muscle and bone health; the direct impact on IBS symptoms however was unchanged.

Vitamin D deficiency and IBS

Osteoporosis and IBS

Another area of investigation is the link between IBS and osteoporosis. The small intestine is responsible for absorbing important nutrients, such as calcium and vitamin D which work hand in hand to contribute towards maintaining healthy bones. 

So if the small intestine is sensitive, you may experience heightened reactivity which can affect how well it absorbs nutrients.

The prevalence of osteoporosis in IBS patients3 is high, with research confirming that the risk of osteoporosis in IBS patients is significantly higher than in patients who do not suffer with the condition. 

Early intervention is advised by researchers to prevent the development of osteoporosis, with counter measures including weight-bearing exercise, ensuring vitamin D and calcium levels are sufficient, and early screening for osteoporosis. However further studies are required to confirm the most effective course of action. 

Vitamin D Toxicity

The best way to increase your Vitamin D levels is to get outdoors if you can, as your body generates vitamin D when exposed to direct sunlight. During the winter months this becomes difficult and you may consider taking a supplement, however there are risks.

If you take too much vitamin D in supplement form, you can be in danger of building up too much calcium in your body. This can cause something called hypercalcaemia, also known as Vitamin D Toxicity, which can cause damage to the kidneys and heart, and actually weaken your bones.

To avoid such side effects, be sure to consult your doctor so that you know you’re taking the right amount of vitamin D for your body, in the right way.

As a general rule, an adult needs 10 micrograms of vitamin D per day. Taking more than 100 micrograms per day could be harmful6.

The wider benefits of Vitamin D

There’s another fantastic reason why ‘The Sunshine Vitamin’ is a superbly appropriate name for this essential mineral.

Further research suggests that Vitamin D supplements may actually protect against depression thanks to a review published in the National Library of Medicine5.

The review summarised multiple sources of information and evidence on the association between Vitamin D levels in the body and depression through observational studies and later, clinical trials to evaluate whether raising Vitamin D levels could in fact reduce the risk or severity of depression.

This suggests that the benefits of Vitamin D could perhaps support the maintaining of a healthy body and mind.

Further Information

To find out more about Vitamin D and if this is a supplement you should be considering, make sure you consult your GP or regular healthcare practitioner to make sure it’s suitable for you. For more information on how Vitamin D can support your health visit the NHS website.


  1. British Medical Journal : Vitamin D associates with improved quality of life in participants with irritable bowel syndrome: outcomes from a pilot trial
  2. University of Sheffield: The vitamin that helps IBS
  3. National Library of Medicine:The association between irritable bowel syndrome and osteoporosis: a systematic review and meta-analysis

  4. University of Sheffield: Vitamin D supplements ineffective treatment for painful IBS symptoms
  5. National Library of Medicine: Vitamin D and Depression: The Evidence from an Indirect Clue to Treatment Strategy
  6. NHS Website: Vitamin D