To evaluate the effect of Lactobacillus brevis G-101 on absorption of monosodium glutamate (MSG), we orally administered MSG with or without G-101 in mice and measured the maximum concentration (Cmax) and blood concentration curve (AUC) of MSG and ${gamma}$-aminobutyric acid (GABA). Oral administration of G-101 ($1{ imes}10^9CFU/mouse$) potently inhibited Cmax and AUC of MSG by 97.8% and 94.3%, respectively (p < 0.05), but increased those of GABA by 32.1% and 67.7%, respectively (p < 0.05). G-101 inhibited the absorption of MSG. These results suggest that G-101 may reduce the side effect of MSG by inhibiting the absorption of MSG.