Pyridoxine and Levodopa in The Treatment of Parkinsonism

To the Editor.— In his letter appearing in the February 28th, 1972 issue ofThe Journal,1Dr. van Woert rightfully calls attention to the potential hazard of dietary restriction of pyridoxine hydrochloride during levodopa therapy for parkinsonism. It is indeed regrettable that some physicians and pharmaceutical companies have seen fit to recommend such dietary advice without evidence that this is a desirable, let alone a safe thing to do. In our original report2describing the reduction of the therapeutic effectiveness of levodopa when pyridoxine is administered concomitantly, we were careful to point out that this only occurred with daily supplemental doses of the order of 10 to 25 mg and on some occasions 5 mg. No evidence was found, nor did we imply that the amount of pyridoxine contained in the standard daily diet, estimated to be less than 1 mg a day, would interfere with the therapeutic