1983 Volume 49 Issue 2 Pages 54-58
As human waste is collected by Japanese communities, the human waste can be utilized in comparative nutrition research. We can attempt both qualitative and partially quantitative analysis of the elements contained in human waste. Human waste contains a total of about 20 elements, including Na, K, Ca, Mg, Fe, Si, Al, and so on. This research focused on 5 elements (Na, K, Ca, Mg, and Fe), and utlilized the methods of filtration and precipitation. Quantitative analysis of the filtrate and of the clarified liquid 'resulting from the precipitation process, revealed a variation by method in the amounts of Ca, Mg, and Fe present. Amounts of Na and K were not so variable. The postulated explanatior is that the Ca, Mg, and Fe are insoluble, whereas the Na and K are soluble, and therefore present in both liquids. Accordingly, it would appear necessary, in nutrition research based on human waste analysis, to homogenize the waste, in order to obtain representative samples and assure accurate measurement of the elements. As there is seasonal variation in diet, individual preference, and regional diversity, we must assume that it is necessary to consider these differences in accounting for fluctuations in the quality and quantity of elements found in human waste. This is the subject of my proposed future research.