In vitro assessment of histamine and lactate production by a multi-strain synbiotic.

Recent studies suggest histamine and d-lactate may negatively impact host health. As excess histamine is deleterious to the host, the identification of bacterial producers has contributed to concerns over the consumption of probiotics or live microorganisms in fermented food items. Some probiotic products have been suspected of inducing d-lactic-acidosis; an illness associated with neurocognitive symptoms such as ataxia. The goals of the present study were to test the in vitro production of histamine and d-lactate by a 24-strain daily synbiotic and to outline methods that others can use to test for their production. Using enzymatic based assays, no significant production of histamine was observed compared to controls (P > 0.05), while d-lactate production was comparable to a commercially available probiotic with no associated health risk. These assays provide a means to add to the safety profile of synbiotic and probiotic products.