Megaloblastic Anemia: Nutritional Considerations

Vitamin B₁₂

In individuals following omnivorous diets, dietary vitamin B₁₂ is usually adequate. However, elderly persons often have poorer B₁₂ absorption due to atrophic gastritis and hypochlorhydria. These individuals may be able to prevent B₁₂ deficiency by taking low–dose crystalline B₁₂ supplements. However, if intrinsic factor deficiency is present, intramuscular injections or high–dose supplements (1 mg/day) will suffice to prevent or treat pernicious anemia.³

Persons who have had gastric bypass surgery are at risk for B₁₂ deficiency,^4,5 as are individuals who have followed vegan diets for many years without taking B₁₂ supplements and their exclusively breast–fed infants. In these groups, the risk for vitamin B₁₂ deficiency is easily eliminated with supplementation.⁴ Individuals who abuse alcohol and those with celiac disease are also at higher risk for deficiency.^6,7

Folate

Due to fortification of grain products with folic acid, anemia resulting from folate deficiency is becoming less frequent. However, alcoholism often leads to poor folate intake and, combined with alcohol’s anti–folate effect, may lead to deficiency.⁸

An autosomal–recessive inborn error of metabolism causes thiamine–responsive megaloblastic anemia (also known as Rogers Syndrome).⁹ Pharmacologic doses of thiamine (25–200 mg/day) correct the hematologic abnormalities associated with this condition.¹⁰

Caution is necessary in prescribing folate supplements. As noted above, folic acid can mask signs of vitamin B₁₂ deficiency.

Orders

See Basic Diet Orders chapter.

Restrict alcohol use. A psychiatric referral, along with substance abuse counseling and Alcoholics Anonymous meetings or other community–based support, may be necessary.

Vitamin B₁₂ supplementation, intramuscular or oral as indicated.

Oral folate supplementation (rule out B₁₂ deficiency prior to treatment).

What to Tell the Family

Megaloblastic anemia is typically caused by a vitamin B₁₂ or folate deficiency and can be easily treated. Appropriate supplementation, increased consumption of folate–rich foods, and reduction of alcohol use can help prevent recurrence. In vegan diets, oral Vitamin B₁₂ supplementation is necessary. If the primary cause of deficiency is alcohol use, the patient will likely need multilevel support facilitated through the primary care provider.