Risk factors:
(1) poor dietary intake, especially after cooking or processing foods
(2) pregnancy and lactation
(3) excessive alcohol use
(4) drugs that impair absorption or that inhibit dihydrofolate reductase (phenytoin, barbiturates, cycloserine, metformin, cholestyramine, salicylazosulfapyridine, methotrexate, trimethoprim, triamterene, pentamidine
(5) malabsorption (celiac disease, tropical sprue, etc)
(6) congenital enzyme deficiencies (methyltetrahydrofolate transmethylase, dihydrofolate reductase, formiminotransferase)
(7) liver disease (results in acquired enzyme deficiencies)
(8) concomitant vitamin B12 deficiency
(9) concomitant scurvy
(10) renal dialysis
(11) chronic exfoliative dermatitis
(12) increased metabolic demands
