Catechins may play a role in reducing the formation of volatile sulfur compounds (VSCs) in the oral cavity according to a study reported in the Journal of Dental Research.

The researchers concluded that the green tea catechin epigallocatechin gallate (EGCg) serves to prevent the formation of methyl mercaptan, a VSC that produces the bad smell associated with halitosis, by inhibiting a gene found in common oral bacteria.

But according to the study, green tea cannot be regarded as a “cure” for bad breath in itself as it is impossible for it to affect every bacteria present in the mouth. 

The researchers also noted that at a concentration of 100 micrograms of EGCg per milliliter the bacteria Porphyromonas gingivalis, a microbial strain associated with gingivitis and periodontal disease, sees slower growth while at concentrations of 187.5 mcg/mL the microorganism is killed. The catechin is not found in these concentrations in brewed green tea, however. 

The scientists pointed out that consuming green tea is not a substitute for regular brushing and flossing.