and a small amount in urine. Chronic alcoholism, poor nutrition, pregnancy, and
diseases that disrupts absorption by the small intestine can lead to an inadequate
amount of folic acid. This can disrupt cellular division. A patient with low folic
acid has nausea and diarrhea and is anorexic, fatigued, and has stomatitis, alo-
pecia, and blood dyscrasias (megaloblastic anemia, leucopenia, and thrombo-
cytopenia). Symptoms usually do not appear for 2 to 4 months after folic acid
storage is depleted.
Vitamin B 12Vitamin B 12 may be found in liver, kidney, fish, and fortified milk and helps con-
vert folic acid into its active form. Vitamin B 12 is essential to synthesize DNA
and promotes cellular division and is required for hematopoiesis (development
of red blood cells in bone marrow) and to maintain the integrity of the nervous
system. Vitamin B 12 is absorbed in the intestine with the aid of an intrinsic
factor produced by gastric parietal cells. Once absorbed, vitamin B 12 binds to
CHAPTER 9 Vitamins and Minerals^147
Dose 1–2 mg/day
Maintenance Male and female: 400 μ g/day
Pregnancy: 600–800 μ g/day
Lactating: 600–800 μ g/day
Pregnancy category A (C if more than RDA)
Deficiency conditions Decreased WBC count and clotting factors, anemias, intestinal
disturbances, depression
Side effects None significant
Adverse reactions High doses of folic acid can mask signs of B 12 deficiency, which
is a risk in the elderly. Patients taking phenytoin (Dilantin) for
seizures should be cautious about taking folic acid because it can
increase the risk of seizures.
During the first trimester of pregnancy, folic acid deficiency can
affect the development of the central nervous system (CNS) of
the fetus; this can lead to neural tube defects such as spina bifida
(a defective closure of the bony structure of the spinal cord) or
anencephaly (lack of brain mass formation)
Contraindications Pernicious, aplastic, normocytic, refractory anemiasFolic acid