Folic acid absorption in patients infected with the human immunodeficiency virus

To determine the folic acid absorption characteristics of patients with human immunodeficiency virus (HIV) infection, a prospective, controlled, result-blind single-dose oral absorption study was conducted. A total of 25 subjects were fasted and given 5 mg oral folic acid; blood samples were taken at time zero and after 30, 60, 90 and 180 min. Absorption of folic acid appears to be significantly impaired in HIV disease, irrespective of the stage of the disease and notwithstanding gastro-intestinal complaints, pathogen-negative diarrhoea or drug treatment. We here present functional data, complementary to previously reported structural and biochemical findings, to support the hypothesis that the virus can cause an enteropathy in the absence of opportunist infection. Folinic acid is absorbed by the same gut mechanism as folic acid, so caution may be needed when employing oral folinic acid rescue procedures in these patients, even when resting serum and red cell folate levels appear to be normal.