What nutritional deficiencies are associated with Inflammatory Bowel Disease (IBD)?

Nutritional Deficiencies in Inflammatory Bowel Disease

Patients with IBD commonly develop iron deficiency (affecting one-third with active disease), vitamin D deficiency (present in 53-69% of patients), vitamin B12 deficiency, and multiple other micronutrient deficits including magnesium, zinc, folate, calcium, and fat-soluble vitamins. 1

Most Common Deficiencies

Iron Deficiency and Anemia

• Iron deficiency anemia occurs in approximately one-third of patients with active IBD and is the most common nutritional deficit. 1
• Iron deficiency causes fatigue, impairs quality of life, and delays recovery from disease flares. 1
• Ferritin levels up to 100 µg/L may still reflect iron deficiency when inflammation is present; transferrin saturation measurement provides additional diagnostic clarity. 1
• Consider other causes including folate deficiency, B12 deficiency, or bone marrow suppression when evaluating anemia in IBD patients. 1

Vitamin D Deficiency

• Vitamin D deficiency (<50 nmol/L) affects 53-66% of Crohn's disease patients and 44-69% of ulcerative colitis patients. 1
• Severe vitamin D deficiency occurs in 27% of Crohn's disease and 36% of ulcerative colitis patients. 1
• Black and Asian ethnic groups demonstrate lower median vitamin D levels compared to white patients. 1
• Vitamin D deficiency associates with increased disease activity, elevated calprotectin, and low bone mineral density. 1

Vitamin B12 Deficiency

• Vitamin B12 deficiency is particularly common and requires monitoring, especially in patients with ileal disease or resection. 1
• Serum B12 levels alone cannot definitively diagnose deficiency; clinical correlation is essential. 2

Additional Micronutrient Deficiencies

Magnesium

• Magnesium deficiency occurs in 13-88% of IBD patients, primarily from increased gastrointestinal losses. 1
• Serum magnesium is unreliable for assessing status since less than 1% of body stores circulate in blood. 1
• Symptoms include abdominal cramps, impaired healing, fatigue, and bone pain. 1

Calcium and Other Minerals

• Up to one-third of IBD patients fail to meet recommended dietary calcium intake. 1
• Zinc deficiency occurs in approximately 15% of patients and may predict disease course. 1, 3
• Potassium deficiency requires monitoring and supplementation, particularly in patients with high stoma output or diarrhea. 1

Fat-Soluble Vitamins

• Deficiencies in vitamins A, D, E, and K occur due to malabsorption, particularly with steatorrhea. 1
• Vitamin K deficiency associates with heightened inflammatory states. 2

Water-Soluble Vitamins

• Folate deficiency is common, especially in patients taking sulfasalazine. 1
• Vitamin B6 deficiency affects approximately 29% of patients. 3
• Vitamin C deficiency occurs in 11% of patients. 3

Mechanisms of Deficiency

IBD patients develop nutritional deficiencies through multiple pathways: chronic mucosal inflammation causing malabsorption, increased gastrointestinal losses from diarrhea, anatomic changes affecting absorptive capacity, inadequate dietary intake from anorexia, and medication-related nutrient interactions. 1, 4

• Corticosteroids increase net protein loss in both children and adults with Crohn's disease. 1
• Disease activity, intestinal resection, and prolonged bowel rest contribute to malabsorption. 1
• Self-directed dietary restrictions without professional guidance worsen nutritional status. 1

Monitoring Considerations

Interpretation Challenges

• Many micronutrients are acute phase reactants, making interpretation during active inflammation unreliable. 1
• Reliable clinical interpretation requires CRP <20 mg/L for plasma zinc, <10 mg/L for selenium/vitamin A/vitamin D, and <5 mg/L for vitamin B6/vitamin C. 1
• Ferritin, copper, and other markers increase with inflammation, while folate, selenium, and zinc decrease. 1

Screening Recommendations

• All IBD patients require assessment of nutritional status and screening for weight loss at each clinic appointment and hospital admission. 1
• Micronutrient deficiencies should be checked regularly, at least annually, even during remission. 1
• Deficiencies may persist even in apparently well-nourished individuals. 1

Clinical Pitfalls

• Deficiencies occur in more than half of IBD patients and are more common in Crohn's disease than ulcerative colitis, and more prevalent during active disease than remission. 2
• Daily multivitamin supplementation may correct most deficiencies but does not guarantee adequacy; iron, zinc, and vitamin D typically require specific replacement regimens. 1
• Poor compliance with supplementation is common, particularly in adolescents, necessitating patient education about rationale. 1
• Oral iron supplementation should not exceed 100 mg elemental iron daily in inactive disease and should be avoided entirely during active inflammation due to impaired absorption. 1

1, 4, 3, 2