What causes vitamin B deficiency?

Causes of Vitamin B Deficiency

The most common causes of vitamin B deficiency are low dietary intake, malabsorption issues (particularly atrophic gastritis affecting up to 20% of older adults), medication use (especially proton pump inhibitors), and age-related physiological changes. 1

Causes of Specific B Vitamin Deficiencies

Vitamin B12 (Cobalamin) Deficiency

• Food-bound malabsorption is the most common cause of B12 deficiency, primarily due to atrophic gastritis which affects up to 20% of older adults 1
• Widespread use of proton pump inhibitors and H2 receptor antagonists reduces stomach acid production necessary for B12 absorption 2, 3
• Strict vegetarian or vegan diets as B12 is not present in foods of plant origin 4
• Medications including metformin, colchicine, phenobarbital, pregabalin, and primidone can interfere with B12 absorption 2, 3
• Malabsorptive conditions such as inflammatory bowel disease, celiac disease, or history of bariatric surgery 3, 5
• Gastric or small intestine resections that reduce absorption surface area 5
• Pernicious anemia (autoimmune condition affecting intrinsic factor production) 4, 6

Folate Deficiency

• Low dietary intake is the primary cause 1
• Poor consumption of green leafy vegetables, legumes, and liver 1
• Medication interactions affecting absorption 1
• Malabsorptive conditions 1
• Increased requirements during pregnancy 1

Riboflavin Deficiency

• Low dietary intake of milk, dairy foods, and fortified cereals 1
• Poor consumption of riboflavin-rich foods 1

Vitamin B6 Deficiency

• Age-related changes in requirements 1
• Low consumption of lean meat, milk, dairy foods, and fortified cereals 1
• Medication interactions 1

Risk Factors and Vulnerable Populations

• Older adults (aged 65+ years) are at significantly higher risk due to:

  • Age-related physiological changes affecting absorption 1
  • Multiple medication use that can interfere with B vitamin metabolism 1
  • Reduced food intake and limited dietary variety 1
  • Possible economic limitations affecting food choices 1

• Socioeconomic factors:

  • Lower socioeconomic status groups have reduced access to fresh, nutrient-dense foods 1
  • Economic limitations may lead to less varied diets 1

• Medical conditions:

  • Gastrointestinal disorders including inflammatory conditions 1
  • Cancer and diabetes can affect nutrient absorption and metabolism 1
  • Long-term use of certain medications (proton pump inhibitors, metformin) 3, 5

Clinical Implications

• B vitamin deficiencies are associated with increased risk of:

  • Cardiovascular disease 1
  • Cognitive dysfunction 1
  • Osteoporosis 1
  • Depression and anxiety (particularly with folate, B6, and riboflavin deficiencies) 1
  • Neurological damage (especially with B12 deficiency) 4, 7

• Vitamin B12 deficiency can lead to:

  • Megaloblastic anemia 7
  • Irreversible neurological damage if left untreated for more than 3 months 4
  • Peripheral neuropathy and ataxia 3
  • Cognitive impairment and psychosis 7

Prevention Strategies

• Dietary diversification with emphasis on:

  • Lean meat, milk, and dairy foods for B12 and B6 1
  • Green leafy vegetables, legumes, and liver for folate 1
  • Fortified breakfast cereals as practical sources of multiple B vitamins 1

• Supplementation considerations:

  • Oral B12 supplements for those with dietary limitations (vegans/vegetarians) 4, 5
  • Intramuscular B12 for those with malabsorption issues 6
  • Increased fortification levels of B12 in foods for older adults 1

• Regular monitoring of at-risk populations:

  • Adults over 75 years should be considered for B12 screening 5
  • Those on long-term medications like metformin (>4 months) or PPIs (>12 months) 5

B vitamin deficiencies remain a significant health concern, particularly in older adults and those with limited dietary intake or absorption issues. Early identification and appropriate management are essential to prevent potentially irreversible neurological and hematological complications.