A 3-month study was conducted in flood victims from affected villages in the Tumpat district, Kelantan. Participants were given either probiotic, Bifidobacterium infantis M63 (M-63 group) or no probiotics (control group) for three months. At baseline and 3-month, participants were assessed for thewater, sanitation and hygiene (WaSH) practices, abdominal symptoms, breath testing for hydrogen and methane to detect the presence of SIBO and also fecal samples for gut microbiota profiling.