Abstract: The pathogeny of Kaschin Beck Disease and keshan Disease have not known yet by now. Some scholars think that it is resulted from the biological toxin and some think that the chemigeological factor is their pathogeny. Author agree the later view. By co operative study with the medical workers for several ten years, we found that the geographical distribution of Kaschin Beck Disease and Keshan Disease coincided with the distribution of low selenium zone in China. So that the pathogenical doctrine of selenium deficiency in environment about these two endemic diseases was suggested. It was thought that Kaschin Beck Disease and Keshan Disease were actually environmental diseases. The prevention and cure of them therefore should started with improving local environment for the permanent control of these two diseases. Based on this consideration, this study increased selenium intake of local residents by improving the cycle of nutrional material such as selenium in food chain, and finally control these two endemic diseases. The serious affected area of Kaschin Beck Disease and Keshan Disease in loess plateau, Binxian County, Shaanxi province was selected for the example study on spraying Se on leaf of wheat, vegetables and adding Se into diet (bread) to control these two diseases from 1992 to 1995. The result of the example study shown that the Se concentration in wheat sprayed selenium raised to 0 081 μg/g, it was obviously higher than that (0 009 μg/g) of wheat unsprayed selenium. The Se in diet from experimental village reached 0 076 μg/g and higher than that (0 014 μg/g) of control village. The average Se intake of residents in experimental village raised from 13 40 g/person. day to 60 39 μg/person.day. The X ray positive rate of Kaschin Beck Disease in experimental village came down from 43 33% to 6 45% and came up to the natioal control standard of Kaschin Beck Diease. This indicated that it was obvious effective to prevent Kaschin Beck Disease and Keshan Disease using trace element selenium, and that selenium really relates to the prevalence of these two diseases.

Key words: food link, selenium flux, Kaschin Beck Disease, Keshan Disease