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Vitamin D supplements and their effect on mental health in people with bowel disorders

Vitamin D supplements and their effect on mental health in people with bowel disordersInflammatory bowel diseases (IBD) and irritable bowel syndrome (IBS) are common chronic bowel diseases. Earlier studies show that supplementation with vitamin D can alleviate local symptoms by strengthening the immune defense and controlling inflammatory processes. In a new review article, scientists have looked closer at how supplements of vitamin D can also improve mental health in patients with inflammatory bowel diseases and irritable bowel problems.

Inflammatory bowel disease (IBD) includes conditions such as ulcerative colitis and Crohn’s disease. Both diseases are treated with different types of medicine and in severe cases, the affected portion of the intestine is removed surgically (colectomy). Chronic bowel diseases have become increasingly widespread in the past decades, and factors such as stress, unhealthy eating habits, antibiotic use, overgrowth of harmful gut bacteria and fungi, and food intolerance may very well contribute to the problem. Inflammatory bowel disease and irritable bowel greatly affect quality of life, depending on the type and severity of the disease. Patients suffering from inflammatory bowel disease and irritable bowel are often affected more than others by mental disorders, typically with problems such as depression and anxiety. It is therefore relevant to look closer at the facts that may improve mental health in patient with these widespread bowel disorders.

  • Ulcerative colitis is a chronic inflammatory condition in the large intestine with symptoms such as pain, frequent and sometimes bloody stool, diarrhea, tiredness, discomfort, and anemia.
  • Crohn’s disease is a chronic inflammatory condition that can occur anywhere in the gastro-intestinal tract. However, it is typically located in the passage between the small and large intestine. The typical symptoms are stomach pain, diarrhea, weight loss, fever, and tiredness.
  • Irritable bowel affects around 15 per cent of the population, and the disease is typically associated with abdominal bloating, pain, and alternating stool consistency.

The background for looking closer at diet and vitamin D’s role in bowel disease

Multiple meta-analyses have shown that dietary improvement may reduce the symptoms of anxiety and depression. Dietary improvements are also important for the treatment of inflammatory bowel diseases and irritable bowel syndrome.
It can be difficult to get enough vitamin D from dietary sources, and an estimated one billion people worldwide are believed to lack vitamin D.
Science has already demonstrated the important role of vitamin D in the brain, nervous system, and mental well-being. Several studies and meta-analyses have shown how vitamin D supplements are able to reduce the symptoms of anxiety and depression.
Based on this knowledge, the scientists behind the new review article wished to investigate how vitamin D affect the mental health in adult pats wientith inflammatory bowel diseases and irritable bowel.

Vitamin D supplements have a positive effect on mental health

The researchers systematically trawled through different databases with studies of vitamin D and bowel diseases and ended up with 10 relevant studies which they reviewed. Four studies looked at inflammatory bowel diseases, while the six others looked at irritable bowel syndrome.
All studies looked at how vitamin D taken in widely different doses affected the symptoms of the mentioned bowel diseases when compared to placebo. Vitamin D was administered for at least six weeks in daily doses of 25-125 micrograms. The patients’ blood levels of the nutrient were measured.
Mental health was primarily assessed by looking at quality of life, depression, and anxiety. The majority of studies revealed that vitamin D supplementation had a positive effect on the mental health of patients with inflammatory bowel disease and irritable bowel.
The scientists also mention that the mentioned gastrointestinal disorders may be connected to a number of other mental problems such as stress, nervousness, low self-esteem, loneliness, and suicidal behavior. There seems to be a great need for improved therapies for chronic gastrointestinal disorders and accompanying mental diseases. The scientists suggest vitamin D supplementation as being relevant for improving mental health, and they call for additional studies of the connection.
The new review article is published in Nutrients and supports earlier studies that show a link between vitamin D and bowel diseases.

Bowel function and mental balance

Our gut is also known as our “third brain” because the billions of bacteria in our intestine produce a number of the signaling substances that help our brain function correctly. Imbalances in our gut flora may therefore result in things such as depression and other mental disorders.

The link between low vitamin D, inflammation, and irritable bowel

A number of studies have found low levels of vitamin D in inflammatory bowel diseases and irritable bowel. This can impair the intestinal immune system, which is in direct contact with microorganisms from the surrounding environment. Lack of vitamin D also increases the risk of chronic inflammation.
A study from Saudi Arabia looked closer at 112 adults with irritable bowel and lack of vitamin D. Half the participants got 50 micrograms of vitamin D daily for six months, while the other half got placebo during the same period. It turned out the patients in the vitamin D group experienced significant improvements of their symptoms compared with the placebo group. Th study is published in The Saudi Journal of Gastroenterology.

Widespread lack of vitamin D and relevant supplementation

Our primary source of vitamin D is the sun during the summer period. In the winter period, on the other hand, we don’t get enough vitamin D, and our vitamin D status is also limited by things like spending too much time indoors. Also, overweight people, diabetics, and people with dark skin synthesize less of the nutrient.
The need for vitamin D varies from person to person. Vitamin D supplements are available in different strengths, and there are some products that are suited for patients with chronic bowel diseases.
EU’s Scientific Committee on Food has set a safe daily upper intake level for vitamin D which is 100 micrograms for adults, including pregnant and breastfeeding women.
Vitamin D is lipid-soluble. Therefore, it is easiest for the body to absorb and utilize vitamin D when the nutrient is dissolved in oil in soft gelatin capsules.

Vitamin D’s role in intestinal health and mental health

  • Important for the intestinal immune system that attacks harmful bacteria and fungi
  • Counteracts inflammation that is often seen in bowel diseases and depression
  • Important for numerous brain functions
  • Helps build and protect neurons
  • Activation of tryptophan and the serotonin synthesis that is inhibited in connection with depression


Dominika Glabska et al. Vitamin D Supplementation and Mental Health in Inflammatory Bowel Diseases and Irritable Bowel Syndrome Patients: A Systematic Review. Nutrients 19 October 2021

Dogan-Sander et al. Inflammation and the Association of Vitamin D and Depressive Symptomatology. Nutrients 2021

Xi-Xi Li et al. Vitamin D deficiency associated with Crohn´s disease and Ulcerative colitis: a meta-analysis of 55 observational studies. Journal of Translational Medicine 2019

Shi, Sheng-Mei MB et al. Effectiveness of vitamin D for irritable bowel syndrome. Medicine 2019

Doaa El Amrousy et al. Vitamin D supplementation in adolescents with irritable bowel syndrome: Is it useful. A randomized controlled trial. Saudi J Gastroenterol 2018

Simon Tazzyman et al. Vitamin D associates with improves quality of life in participants with irritable bowel syndrome: outcomes from a pilot trial. BMJ Open Gastroenterology 2015

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