Carnitine has beneficial vitamin-like qualities and functions as a compatible solute. The presence of L-carnitine in infant formula significantly promoted the growth of Listeria monocytogenes at 7°C, whereas disruption of the genes for carnitine and glycine betaine uptake compromised growth of the L. monocytogenes mutant in formula containing carnitine that was stored at 7°C. Thus, addition of carnitine to baby formula may pose a potential food safety risk.