Vitamin B12 deficiency causes fatigue, neurological issues, and anemia due to impaired red blood cell production. It develops gradually, often taking years before symptoms appear.
Vitamin B12 (cobalamin) supports DNA synthesis, red blood cell formation, and neurological function. Deficiency occurs when intake is insufficient or absorption is impaired. The liver stores B12 for years, masking deficiencies until reserves deplete.
Early symptoms include fatigue, weakness, and constipation. As deficiency progresses, neurological symptoms emerge:
| Cause | Description |
|---|---|
| Pericious anemia | Autoimmune condition destroying stomach cells that produce intrinsic factor, necessary for B12 absorption |
| Dietary deficiency | Vegans and vegetarians at higher risk due to lack of animal products, primary B12 sources |
| Malabsorption | Conditions like celiac disease or Crohn's disease damage the small intestine, impairing absorption |
Doctors diagnose deficiency through blood tests measuring B12 levels and assessing red blood cell size. Treatment depends on severity:
Ongoing treatment may be needed for conditions causing malabsorption. The National Institutes of Health recommends lifelong supplementation for pernicious anemia patients.
Adults need 2.4 mcg of B12 daily. Food sources include clams, liver, fish, meat, poultry, eggs, and fortified cereals. Supplements are available for those at risk of deficiency.
I once worked with a vegan who developed B12 deficiency after several years. After supplementing with B12 and adjusting her diet, her energy levels improved within weeks.
Many confuse B12 deficiency symptoms with other conditions like chronic fatigue syndrome or fibromyalgia. Unlike these conditions, B12 deficiency responds well to targeted treatment. Another misconception is that oral supplements work for everyone; those with absorption issues require injections.