Vitamin Deficiency
Vitamins are essential nutrients the body needs in small amounts. Deficiencies — from inadequate intake, poor absorption, or increased needs — can cause a wide range of symptoms, many reversible with replacement.
Table of Contents
Quick Facts
- ICD-10: E50–E56
- Common deficiencies: Vitamin D, B12, iron
Common Vitamin Deficiencies
Vitamin D
Affects bone health, immunity. Symptoms: fatigue, bone pain, muscle weakness, increased fracture risk.
Vitamin B12
Affects nerves and blood. Symptoms: fatigue, tingling/numbness, memory problems, anemia, sore tongue. Common in older adults, vegans, and people on metformin or acid-blockers.
Folate (B9)
Important for cell division. Deficiency causes anemia; in pregnancy can cause neural tube defects.
Iron (not a vitamin but often grouped)
Causes anemia, fatigue, restless legs, hair loss.
Vitamin A
Affects vision. Deficiency causes night blindness, dry eyes; rare in developed countries.
Vitamin K
Important for clotting. Rare deficiency in adults; newborns receive injection at birth.
Vitamin C
Severe deficiency causes scurvy (rare in developed countries).
Common Causes
- Poor diet variety
- Malabsorption (celiac disease, IBD, bariatric surgery)
- Medications (metformin, PPIs, methotrexate)
- Limited sun exposure (vitamin D)
- Restrictive diets (vegan diets need B12 supplementation)
- Alcohol use
- Older age (reduced absorption)
Diagnosis
- Blood tests for specific vitamins
- Methylmalonic acid and homocysteine for B12 status
- Investigations into underlying cause (especially in B12 deficiency)
Treatment
- Replacement (oral or injection)
- Dietary counseling
- Address underlying cause
- Follow-up testing to confirm response
References
- National Institutes of Health Office of Dietary Supplements. Vitamin Fact Sheets.