100 subjects took part in the screening by U-gal test and forty-five (45) qualified subjects (stratified by male to female approximate ratio 1:1) will be enrolled into the study with assumed 11.1% attrition rate to keep 20 subjects per group to complete the cross-over study. Subjects will be enrolled in the study site authorized by Xin Hua Hospital during the screening phase. Sun Jianqin, Professor, leading PI, is responsible for the academic guidance to define all qualified subjects. The study will be conducted by the team of PIs and monitored by SPRIM CHINA in accordance with Chinese Good Clinical Practices (CGCP's). Subjects will sign the informed consent form before study intervention. Eligible subjects will be randomized into 2 groups, and one of two possible products sequences will be assigned, A1 milk or A2 milk. Subjects completed 2 weeks A1 or A2 intervention after initial 2 weeks of washout, and then cross over to the opposite intervention for 2 weeks after second 2 weeks of washout. The efficacy of the study products was evaluated by biomarkers in the blood or feces and linked questionnaires at the duration of the cross-over study.