Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 12/10/1999
Publication Date: 3/15/2000
Citation: Penland, J.G., Davis, C.D., Finley, J.W., Pettit, R.E. 2000. Moderately high dietary intakes of manganese do not cause neurologic signs or symptoms in healthy adult women [abstract]. Federation of American Societies for Experimental Biology Journal. 14:A262.
Technical Abstract: Exposure to high concentrations of manganese (Mn) via the air or contaminated water has been linked to numerous neurologic signs and symptoms, including tremors, rigidity, absence of eye blinking and impaired postural reflexes. However, Mn toxicity from food intakes is unknown, although neurologic symptoms were reported in one individual consuming large amounts of Mn supplements for several years. Nonetheless, the current Reference Dose (RfD) for Mn is 10 mg/d (70 kg male) and the most recent Lowest Observable Adverse Effect Level (LOAEL) set by the EPA is 4.2 mg Mn/d. These standards raise concerns when contrasted with estimated intakes from common Western (2-3 mg Mn/d) and vegetarian (10-17 mg Mn/d) diets. The current Estimated Safe and Adequate Daily Dietary Intake (ESADDI) for Mn is 2-5 mg/d. We directly evaluated possible neurologic consequences of moderately high dietary Mn intakes as part of a highly controlled metabolic study of Mn bioavailability. Eleven healthy women were fed either 1 or 20 mg Mn/d for 8 wk in a crossover double-blind design. During the last wk of each diet period, women were examined by a licensed clinical neurologist (R.E.P.) for the presence and severity of over 75 neurologic signs and symptoms. None of the women showed any signs or symptoms at either examination. Therefore, a dietary Mn intake of 20 mg/d did not result in any neurologic signs or symptoms. Findings indicate that dietary intakes of Mn in the range consumed by many vegetarians are unlikely to result in neurologic problems. However, possible neurologic and other consequences of longer term dietary intakes at these concentrations still need to be examined.