Prediction of human nitrogen balance from food intake data.

Nitrogen balance data from 1,813 nitrogen balance days on adults and 141 nitrogen balance days with young children were compared with that predicted from food intake and body weight data using the equations developed by Miller and Payne. In addition, 14-day growth data from 378 infants were also compared with those predicted assuming a constant relationship between positive nitrogen balance and weight gain. The original Miller-Payne equations were found to predict with poor accuracy, and various modifications have been proposed which include changing of the exponent for body weight, addition of a factor for activity, lowering of the value for endogenous nitrogen losses, and attempting to allow for the nonlinear relationships at low levels of intake. New equations are proposed including these modifications which can significantly improve the accuracy of prediction of nitrogen balance and growth from food intake and body weight data.