In 2018, Kyushu Women's University conducted joint research with the Kokura Memorial Hospital to reproduce the administration method of enteral nutritional supplements using artificial gastric juice I (pH 1.2) and artificial gastric juice II (pH6.8). As a result, it was considered that a viscosity of 500 mPa · s or more was required to prevent the risk of diarrhea and reflux. In addition, since enteral nutrition and artificial gastric juice were separated without being mixed uniformly, the viscosity of the filtrate was measured in this study and examined as a viscosity index for risk prevention. In artificial gastric juice I after injecting enteral nutrients, the filtrate accounted for about 68-81%, and in artificial gastric juice II, about 88-99%. Their viscosities were 2.1 to 415.1 mPa · s and 500 mPa · s or less, but this measurement method could not take into account the increase in viscosity over time. It is possible that the viscosity of the separated filtrate increases and slowly flows into the intestinal tract in the actual human stomach, and clinical verification is considered necessary in the future.