Do deficiencies in selenium, zinc, or iron contribute to gastrointestinal symptoms such as diarrhea and bowel issues?

From the Guidelines

Deficiencies in zinc, particularly, have been shown to contribute to gastrointestinal symptoms such as diarrhea, and supplementation can help alleviate these symptoms, as evidenced by the 2017 Infectious Diseases Society of America clinical practice guidelines 1.

Key Points to Consider

• Zinc deficiency is well-documented to cause persistent diarrhea, particularly in children, and oral zinc supplementation can reduce the duration of diarrhea in children 6 months to 5 years of age who reside in countries with a high prevalence of zinc deficiency or who have signs of malnutrition 1.
• Selenium and iron deficiencies may also contribute to gastrointestinal disturbances, including diarrhea, although the evidence is less clear-cut for these minerals compared to zinc 1.
• Iron deficiency, especially in individuals with inflammatory bowel disease, should be managed by determining whether the deficiency is due to inadequate intake, absorption, or loss of iron, and treating the underlying cause, such as gastrointestinal bleeding or inflammation 1.
• Patients with inflammatory bowel disease are vulnerable to micronutrient deficits due to gut loss from diarrhea, malabsorption, and inadequate dietary intake, and should be checked for micronutrient deficiencies regularly, at least once per year 1.

Recommendations for Supplementation

• Zinc supplements (15-30 mg daily for adults) may help alleviate diarrhea symptoms in individuals with zinc deficiency 1.
• Selenium supplementation (55 mcg daily for adults) may also be beneficial for individuals with selenium deficiency, although the evidence is less clear-cut 1.
• Iron supplementation (typically 325 mg ferrous sulfate 1-3 times daily) should only be considered for individuals with confirmed iron deficiency, as excessive iron supplementation can worsen gastrointestinal symptoms 1.

Importance of Confirming Deficiencies

• It is essential to confirm deficiencies through blood tests before beginning supplementation, as excessive supplementation of any of these minerals can worsen gastrointestinal symptoms 1.
• Regular monitoring of micronutrient levels, perhaps annually, is necessary to screen for deficiencies and adjust supplementation regimens as needed 1.

From the FDA Drug Label

Symptoms of zinc overdosage also included hyperamylasemia, thrombocytopenia, anemia, vomiting and diarrhea

Deficiencies in zinc may contribute to gastrointestinal symptoms, but the label does not provide direct information on the role of selenium or iron deficiencies in gastrointestinal symptoms such as diarrhea and bowel issues. However, it does mention that zinc overdosage can cause diarrhea and vomiting. 2

From the Research

Deficiencies in Selenium, Zinc, or Iron and Gastrointestinal Symptoms

• Deficiencies in zinc have been linked to gastrointestinal symptoms such as diarrhea and bowel issues 3, 4, 5, 6.
• Zinc supplementation has been shown to be effective in reducing the duration and severity of diarrhea in children 3, 4, 5, 6.
• A study found that adding zinc to iron treatment increases hemoglobin response, improves iron indexes, and has positive effects on diarrhea 5.
• Another study found that zinc supplementation may shorten the average duration of diarrhea by around half a day in children older than six months of age 6.
• However, the evidence for the effectiveness of zinc supplementation in reducing diarrhea in children less than six months of age is limited 6.
• Selenium deficiency has been linked to inflammatory bowel disease, with lower serum selenium levels found in patients with active colitis or small bowel disease 7.
• Iron deficiency has also been linked to gastrointestinal symptoms, with iron supplementation found to improve iron indexes and reduce diarrhea in children with iron deficiency anemia 5.
• The relationship between selenium, zinc, or iron deficiencies and gastrointestinal symptoms is complex and may be influenced by various factors, including the severity of the deficiency, the presence of other nutritional deficiencies, and the overall health status of the individual 3, 4, 5, 6, 7.

Specific Nutrient Deficiencies and Gastrointestinal Symptoms

• Zinc deficiency:
  • Linked to diarrhea and bowel issues 3, 4, 5, 6
  • Zinc supplementation effective in reducing diarrhea duration and severity 3, 4, 5, 6
• Selenium deficiency:
  • Linked to inflammatory bowel disease 7
  • Lower serum selenium levels found in patients with active colitis or small bowel disease 7
• Iron deficiency:
  • Linked to gastrointestinal symptoms, including diarrhea 5
  • Iron supplementation improves iron indexes and reduces diarrhea in children with iron deficiency anemia 5