Metabolic balance of manganese in young women.

Few metabolic balance studies of manganese have been reported and the results from these are bewildering. Except for the study of Kent & McCance (1941) on two women, each study has indicated a daily accumulation of M n in both normal men and normal women which approaches in a matter of weeks the estimated total body pool of 12-20 mg M n (Cotzias, 195s). Schroeder, Balassa & Tipton (1966) confirmed earlier observations that the concentrations of Mn, characteristic for each tissue, remained remarkably constant after the first few weeks of life. There seemed no tendency to accumulate or lose Mn with ageing beyond the nceds for growth. Retention of an element occurs when the total intake is greater than the total output, and its measurement is dependent upon the accuracy of all experimental procedures. For an element like M n which is believed to be poorly absorbed, calculated retentions of up to 63% of the total intake which have been reported for normal subjects are hardly credible, and are unlikely to be caused solely by an overestimate of the intake. There may be another pathway for the excretion of M n beyond the major output in the faeces and the almost negligible amounts lost in the urine and from the skin. Cotzias (1962), however, emphasized the difficulties in estimating Mn, the questionable specificity of many of the methods, the ubiquitous nature of Mn, and the ease of contamination at each stage of any analytical procedure. This study reports the satisfactory use of atomic absorption spectrophotometry for estimation of Mn in food, faeces and urine, and the measurement of the metabolic balance of Mn for four young women.