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What deficiency does IBS cause?

Irritable bowel syndrome (IBS) is a common disorder that affects the large intestine (colon). The most common symptoms are abdominal pain, bloating, diarrhea and constipation. IBS is associated with a few nutritional deficiencies that may develop as a consequence of the condition or the dietary restrictions that people with IBS often follow. This article explores what deficiencies IBS can lead to.

Vitamin B12 Deficiency

One of the most common nutritional deficiencies associated with IBS is a vitamin B12 deficiency. Vitamin B12 plays important roles in red blood cell formation, cell metabolism, nerve function and DNA synthesis [1].

Some research shows that vitamin B12 deficiency is more common in people with IBS than in the general population.

For example, a study in 100 people with IBS found 31% were deficient in vitamin B12, compared to 5% of healthy controls [2].

Another study found that vitamin B12 levels were significantly lower in patients with IBS and diarrhea compared to healthy controls [3].

There are a few reasons why vitamin B12 deficiency is more common in those with IBS:

  • Medications used to treat IBS symptoms, like proton pump inhibitors, can reduce absorption of vitamin B12 from food [4].
  • IBS can damage the small intestine, leading to poor absorption of vitamin B12 and other nutrients [5].
  • Dietary restrictions, like eliminating dairy products, may result in inadequate intake of vitamin B12.

Getting insufficient vitamin B12 over time can cause anemia and peripheral neuropathy. This nerve damage causes numbness and tingling in the feet and hands.

Iron Deficiency

Iron deficiency is also more prevalent among those with IBS compared to the general public.

One study found that 36% of people with IBS had low iron levels [6].

Another study in 200 IBS patients found 62% of women and 32% of men were iron deficient [7].

Iron plays vital roles in oxygen transport and energy production. Low iron levels can cause iron deficiency anemia, which is characterized by fatigue, pale skin and shortness of breath [8].

There are several reasons people with IBS are prone to low iron levels:

  • Inflammation from IBS can damage the intestinal lining, impairing iron absorption [9].
  • IBS medications may hinder iron absorption.
  • Restricted diets, such as a low FODMAP diet, may provide inadequate iron.
  • Blood loss from intestinal bleeding related to IBS.
  • Diarrhea can cause excess loss of iron in the stool.

Correcting iron deficiency usually requires oral iron supplements, along with treating the underlying IBS.

Vitamin D Deficiency

Some research shows vitamin D deficiency is common in IBS patients.

One study in 82 adults with IBS found 69% were vitamin D deficient [10].

Another study found significantly lower blood levels of vitamin D in patients with IBS compared to healthy controls [11].

Vitamin D plays important roles in immune function, bone health, mood regulation and protecting against chronic diseases [12].

Risk factors for vitamin D deficiency in IBS include:

  • Malabsorption due to intestinal damage from inflammation.
  • Medications that reduce vitamin D absorption, such as cholestyramine and steroids.
  • Low sunlight exposure from limited outdoor activity.
  • Inadequate intake from restricted diets.

Deficiency symptoms include bone loss, muscle weakness, pain, fatigue and depression [13].

Correcting vitamin D deficiency involves sunlight exposure, vitamin D-rich foods and oral supplements.

Zinc Deficiency

Zinc deficiency has also been observed in some IBS patients.

One study found that plasma zinc levels were significantly lower in diarrhea-predominant IBS patients compared to controls [14].

Zinc plays essential roles in immune function, protein synthesis, DNA synthesis and cell division [15].

Deficiency can result in hair loss, diarrhea, delayed wound healing, skin lesions, loss of appetite and impaired immunity [16].

Risk factors for zinc deficiency in IBS include:

  • Reduced absorption due to intestinal inflammation.
  • Inadequate dietary intake.
  • Excess zinc loss from diarrhea.

Oral zinc supplements may help correct deficiency. Zinc-rich foods like oysters, meat, beans, nuts and seeds should also be encouraged.

Magnesium Deficiency

Magnesium deficiency has been reported in some IBS studies.

One study found significantly lower serum magnesium levels in patients with IBS compared to healthy controls [17].

Another study showed that 88% of those with IBS had an intracellular magnesium deficiency [18].

Magnesium is needed for energy production, muscle and nerve function, blood sugar control, and blood pressure regulation [19].

Risk factors for magnesium deficiency in IBS include:

  • Inflammation and intestinal damage leading to malabsorption.
  • Medications that deplete magnesium levels.
  • Inadequate dietary intake.
  • Excess loss from diarrhea.

Deficiency can cause muscle cramps, anxiety, fatigue, abnormal heart rhythms and osteoporosis [20].

Magnesium rich foods, like dark leafy greens, nuts and avocado, may help correct deficiency. Supplements are sometimes needed as well.

Folate Deficiency

Folate, also known as vitamin B9, deficiency has been linked to some cases of IBS.

One study found that folate levels were significantly lower in patients with IBS compared to healthy controls [21].

Another study showed that people with IBS who were given folic acid supplements had decreased IBS symptoms and improved quality of life [22].

Folate plays important roles in DNA and protein synthesis, cell division, and mental health. Inadequate folate can cause anemia, brain disorders and birth defects [23].

Risk factors for folate deficiency in IBS include:

  • Reduced absorption from intestinal damage.
  • Excess losses from diarrhea.
  • Dietary restrictions limiting folate-rich foods.
  • Medications that interfere with folate absorption.

Correcting folate deficiency requires increased intake of folate-rich foods, like legumes, leafy greens and citrus fruits, or use of supplements.

Calcium Deficiency

Some studies show that people with IBS tend to have lower calcium levels.

One study found that serum calcium levels were significantly lower in patients with IBS compared to controls [24].

Another study showed that calcium intake was reduced in children with IBS who avoided dairy products [25].

Calcium plays vital roles in bone health, muscle function, nerve transmission and hormone secretion. Inadequate calcium can lead to osteoporosis and increased fracture risk [26].

Potential reasons for calcium deficiency in IBS include:

  • Calcium malabsorption from intestinal damage and inflammation.
  • Medications that reduce calcium absorption.
  • Lower dietary calcium intake, especially with dairy avoidance.
  • Excess fecal calcium losses from diarrhea.

Boosting calcium intake through calcium-rich foods and possibly supplements can help prevent bone loss in IBS patients.

Vitamin A Deficiency

Some studies have found vitamin A deficiency to be more prevalent among IBS patients.

One study showed that vitamin A levels were significantly lower in children with IBS [27].

Another study found that serum vitamin A levels were decreased in patients with diarrhea-predominant IBS [28].

Vitamin A supports immune function, vision, cell communication and reproduction [29].

Deficiency can cause vision problems, infections, skin disorders and delayed growth and development [30].

Risk factors for vitamin A deficiency in IBS patients include:

  • Fat malabsorption leading to reduced vitamin A absorption.
  • Inflammation damaging the intestinal lining.
  • Medications that interfere with vitamin A absorption.
  • Inadequate dietary intake of vitamin A foods.

Increasing vitamin A intake through animal foods and supplements may help correct deficiency.

Selenium Deficiency

Selenium is an essential mineral that plays critical roles in reproductive health, thyroid function, DNA production and protecting against oxidative damage and infection [31].

Some studies have found that patients with IBS tend to have lower blood levels of selenium.

For example, one study showed that plasma selenium levels were significantly lower in children with IBS compared to healthy controls [32].

Potential reasons for selenium deficiency include:

  • Reduced selenium absorption due to intestinal inflammation.
  • Inadequate dietary selenium intake.
  • Medications that impair selenium absorption.

Selenium deficiency can contribute to infertility, hypothyroidism, impaired immunity and heart disease [33].

Increasing dietary selenium through foods like brazil nuts, tuna, eggs and beef or using supplements may help resolve deficiency.


In summary, IBS is associated with higher rates of certain vitamin and mineral deficiencies. The most common ones include deficiencies in vitamin B12, iron, vitamin D, zinc, magnesium, folate, calcium, vitamin A and selenium.

Risk factors for developing micronutrient deficiencies in IBS include reduced nutrient absorption, dietary restrictions, diarrhea, medications and intestinal bleeding.

Deficiencies in these vitamins and minerals can cause a range of symptoms and health conditions, depending on the specific nutrient.

Testing for nutritional deficiencies and correcting them through diet and supplements, while also treating the underlying IBS, can help improve health outcomes in patients.