The present invention aims at preventing foodborne infections. As a candidate for this purpose, the inventors focused on antibacterial acidic liquid diets, which are acidic due to comprising fermented dairy products as protein source. The antibacterial activity of the acidic liquid diets was compared with the antibacterial activity of a neutral liquid diet and the fermented dairy product used as the basic ingredient. Antibacterial effect of fermented milk such as yogurt is already known. However, the acidic liquid diets unexpectedly exhibited an antibacterial effect higher than the basic ingredient (the fermented dairy product) against Gram-positive bacteria such as MRSA, which are important in terms of public health.
