1. A 71-year-old m an com plained to his physician of tiredness, breathlessness, and fatigue. Four years earlier, the patient had undergone total gastrectom y for advanced Zollinger- Ellison syndrom...

1. A 71-year-old m an com plained to his physician of tiredness, breathlessness, and fatigue. Four years earlier, the patient had undergone total gastrectom y for advanced Zollinger- Ellison syndrom e. A blood analysis showed m egaloblastic anem ia. Which of the follow ing statem ents best explains w hy folic acid supplem entation would be contraindicated in this patient? A. The drug would m ask hem atologic signs of vitam in B12 de ciency. B. The drug would block vitam in B12 actions in the central nervous system . C. The drug m ay increase vitam in B12 m etabolism . D. Older patients are especially at risk of folic acid toxicity. E. Gastrectomy com pletely prevents folic acid absorption.