Is a Vitamin D Deficiency Behind Your IBS?

Vitamin D has been receiving a lot of research attention for two reasons:

  1. More information is being gained as to its role in our health.
  2. In the overall population, rates of vitamin D deficiency are increasing.

One small but emerging area of research has to do with vitamin D's relationship with irritable bowel syndrome (IBS).

In this overview, you will become educated about vitamin D, find out what the latest research is uncovering regarding its role in IBS, and how to ensure you are taking in adequate amounts of this important substance.

Fresh eggs, cheese, and milk on counter
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The Role of Vitamin D

Vitamin D is not your typical vitamin. Unlike other vitamins, your body can actually make vitamin D when you're exposed to sunlight. Though often described as a hormone, vitamin D provides the basis for your body to make certain hormones.

Vitamin D is a fat-soluble vitamin, which means that the vitamin can be stored within your body. This is in contrast to water-soluble vitamins which dissolve in water and are available to your body's tissues but are not stored. This distinction is important because the storage factor of a fat-soluble vitamin leaves you at risk for a buildup of the vitamin to toxic levels.

You can get vitamin D through sun exposure, it is found naturally in some foods, it has been added to many fortified foods, and it can be taken in supplement form.

Vitamin D is most important for its role in calcium absorption and in maintaining calcium and phosphate concentrations in your blood. Vitamin D plays an important role in bone health.

Vitamin D also affects immune health, muscle function, and inflammation reduction.

Vitamin D Deficiency

Due to the importance of vitamin D in so many of the body's systems, a deficiency can lead to health problems. This is why your healthcare provider may recommend testing your vitamin D levels.

What Your Vitamin D Levels Mean

Vitamin D levels are often measured in nanomoles per liter (nmol/L). Here's what the different levels mean:

  • Lower than 30 nmol/L: Vitamin D deficiency
  • 30 nmol/L to 50 nmol/L: Vitamin D inadequacy
  • Over 50 nmol/L: Adequate Vitamin D levels for most people
  • Higher than 125 nmol/L: May be associated with health problems

You may be deficient in vitamin D because you don't get enough through your diet, don't get enough sunlight exposure, or can't properly absorb the vitamin.

You are at greater risk for vitamin D deficiencies if:

  • You are an older adult
  • You have dark skin
  • You are very rarely exposed to sunlight
  • You have a health condition that involves fat malabsorption, such as inflammatory bowel disease
  • You are significantly overweight or have had gastric bypass surgery
  • You are following a diet for a milk allergy, lactose intolerance, or you are following an ovo-vegetarian or vegan diet

Irritable Bowel Syndrome (IBS)

Irritable bowel syndrome (IBS) is a condition that affects your gastrointestinal (GI) system, or gut. It can cause symptoms like:

  • Abdominal pain
  • Abdominal cramping
  • Bloating
  • Gas
  • Diarrhea
  • Constipation

IBS is fairly common and affects between 7% and 21% of the general population. Even though it's such a common condition, its cause is still unknown.

Even without a specific known cause, IBS can have various triggers in different people. Symptoms of IBS can be triggered by many different factors, like:

  • Foods high in FODMAPs, a group of carbohydrates that can be hard to digest
  • Spicy foods
  • High-fat foods
  • Stress
  • Depression
  • Anxiety
  • Hormones
  • Bacterial infections in your digestive tract

Vitamin D and IBS

Researchers have recently been looking into a possible connection between a vitamin D deficiency and IBS. This interest was triggered by the fact that vitamin D deficiency has been associated with many chronic conditions. In addition, bone loss from vitamin D deficiency has been observed in several gastrointestinal disorders, including inflammatory bowel disease, celiac disease, and people who have had part of their stomach surgically removed. Of particular relevance to the question as to whether vitamin D plays a role in IBS are research findings that show that IBS patients are at higher risk for osteoporosis.

However, given all of the theoretical factors listed above, a single case study seemed to get the ball rolling in terms of conducting actual studies to shine some light on a possible connection between vitamin D and IBS. According to the report, a 41-year-old woman who had experienced severe symptoms of IBS-D for over 25 years decided to take a high dose of a vitamin D supplement after getting the idea from social media. This intervention resulted in significant improvement of her symptoms, which return whenever she stops taking the supplement. Of course, we can draw no conclusions based on one person's experience, but this report appears to have prompted other researchers to conduct other types of studies on the subject.

Results of a case-control study, which compared vitamin D levels between a group of 60 IBS patients and 100 control group individuals, indicated that IBS patients were significantly more likely to have a vitamin D deficiency. A deficiency was detected in 82 percent of the IBS patients compared to 31 percent of the control subjects.

A pilot study, one in which a very small group of individuals is used to test out a hypothesis, sought to compare a vitamin D supplement with either a placebo or a combination pill of a probiotic and vitamin D. Keeping in mind that a pilot study does not offer information about statistical significance, the results suggested that a large proportion of the IBS subjects tested as having a vitamin D deficiency. Supplementation increased vitamin D and improved quality of life scores but did not significantly improve IBS symptoms.

A larger study compared a six-month trial of a vitamin D supplement with a placebo in a group of 90 IBS patients. The supplement or placebo was described as a "pearl" to be taken every two weeks. The results indicated that the vitamin D supplement was significantly more effective in easing IBS symptoms (including abdominal pain, distension, flatulence, and rumbling) and their severity and quality of life than the placebo. The only symptom not improved by the vitamin D was "dissatisfaction with bowel habits."

Further research is needed to come to any conclusions about the relationship between vitamin D levels and IBS. We also need to keep in mind that although this early research points to a connection, we don't know what is causing what—is the IBS causing the vitamin D deficiency, is the vitamin D deficiency causing the IBS, or is there some other unknown factor contributing to both problems.

How to Increase Your Vitamin D Levels

Although research on the relationship between IBS and vitamin D is far from conclusive, it is important that you make sure that your body has sufficient levels of vitamin D for reasons separate from your digestive problems.

If you have not already done so, speak with your healthcare provider to have your level checked. Once you have a sense of your level, you can speak with your healthcare provider about what things you can do to ensure that your body is getting enough of this essential substance.

Keep in mind that there are three main ways to take in vitamin D:

  • Food: There are not many foods that naturally contain vitamin D. Those that do include fatty fish (mackerel, salmon, tuna), cheese, egg yolks, some mushrooms and cow's liver. Many processed foods have had vitamin D added to them, most notably cows' milk. Other fortified foods include many brands of breakfast cereals, orange juice, and yogurt. 
  • Sun exposure: Exposure to the sun is certainly a way to take in more vitamin D, but clear guidelines for this are hard to find. Sun exposure has been linked to skin cancer. Therefore dermatologists typically recommend that sunscreen is used whenever one is out in the sun to minimize your risk of getting skin cancer. Other branches of medicine suggest that small amounts of sun exposure a couple of times a week may be enough to ensure adequate vitamin D levels within the body. The amount of vitamin D your body can convert for use is also going to depend on the strength of the sunlight, which varies depending not only on time of day but also where you live. Your best bet is to discuss the issue with your healthcare provider to decide on what the most prudent course would be for you in terms of getting sun exposure.
  • Vitamin D supplements: Taking a vitamin D supplement is an additional option for ensuring that your vitamin D levels are sufficient. Interestingly, due to the growing awareness of an overall increased risk of vitamin D deficiency in the overall population, researchers have increased the long-standing guidelines for dosing. The current recommended daily allowance (RDA) is 600 IU a day for individuals aged 4 to 70. The RDA is increased to 800 IU a day for individuals age 71 and older. However, the correct dosage for you should be decided based on a discussion with your healthcare provider, based on your bloodwork, your age, your medical history, and your lifestyle.

Frequently Asked Questions

  • Can low vitamin D cause IBS?

    It's difficult to say whether low vitamin D causes IBS because the exact cause is unknown. However, there is a strong connection between vitamin D deficiency and IBS. Many people with IBS are also low in vitamin D.

  • How can you tell if you have a vitamin D deficiency?

    Your healthcare provider can measure the vitamin D levels in your blood, which is called 25(OH)D serum concentration.

    If your levels are lower than 30 nanomoles per liter (nmol/L), you have a vitamin D deficiency.

12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Colorado State University. Fat-soluble vitamins: A, D, E, and K – 9.315.

  2. NIH Office of Dietary Supplements. Vitamin D.

  3. NIH MedlinePlus. Vitamin D deficiency.

  4. El amrousy D, Hassan S, El ashry H, Yousef M, Hodeib H. Vitamin D supplementation in adolescents with irritable bowel syndrome: Is it useful? A randomized controlled trial. Saudi J Gastroenterol. 2018;24(2):109-114. doi:10.4103/sjg.SJG_438_17

  5. Cleveland Clinic. Vitamin D deficiency.

  6. Chey WD, Kurlander J, Eswaran S. Irritable bowel syndrome: a clinical reviewJAMA. 2015;313(9):949-958. doi:10.1001/jama.2015.0954

  7. National Institute of Diabetes and Digestive and Kidney Diseases. Symptoms and causes of irritable bowel syndrome.

  8. Sprake EF, Grant VA, Corfe BM. Vitamin D3 as a novel treatment for irritable bowel syndrome: single case leads to critical analysis of patient-centred data. BMJ Case Rep. 2012;2012. doi:10.1136/bcr-2012-007223

  9. Khayyat Y, Attar S. Vitamin D deficiency in patients with irritable bowel syndrome: Does it exist?. Oman Med J. 2015;30(2):115-8. doi:10.5001/omj.2015.25

  10. Tazzyman S, Richards N, Trueman AR, et al. Vitamin D associates with improved quality of life in participants with irritable bowel syndrome: outcomes from a pilot trial. BMJ Open Gastroenterol. 2015;2(1):e000052. doi:10.1136/bmjgast-2015-000052

  11. Abbasnezhad A, Amani R, Hajiani E, Alavinejad P, Cheraghian B, Ghadiri A. Effect of vitamin D on gastrointestinal symptoms and health-related quality of life in irritable bowel syndrome patients: a randomized double-blind clinical trial. Neurogastroenterol Motil. 2016;28(10):1533-44. doi:10.1111/nmo.12851

  12. Cleveland Clinic. Sun exposure & skin cancer.

Additional Reading
  • Abbasnezhad A et. al. Effect of vitamin D on gastrointestinal symptoms and health-related quality of life in irritable bowel syndrome patients: a randomized double-blind clinical trial. Neurogastroenterology & Motility.

  • New Recommended Daily Amounts of Calcium and Vitamin D. NIH Medline Plus.

  • Khayyat Y. & Attar S. Vitamin D Deficiency in Patients with Irritable Bowel Syndrome: Does it Exist? Oman Medical Journal. 2015; 30:115-118.
  • Sprake E, Grant V. & Corfe B. Vitamin D3 as a novel treatment for irritable bowel syndrome: single case leads to a critical analysis of patient-centred data. BMJ Case Reports. 2012; bcr-2012-007223.
  • Vitamin D: Fact Sheet for Health Professionals. National Institutes of Health

By Barbara Bolen, PhD
Barbara Bolen, PhD, is a licensed clinical psychologist and health coach. She has written multiple books focused on living with irritable bowel syndrome.