Lactoperoxidase is an enzyme naturally present in human saliva and milk, and it is best known for its antimicrobial properties. Scientific studies have demonstrated that lactoperoxidase, as part of the lactoperoxidase system (LPO system, which includes hydrogen peroxide and thiocyanate), generates hypothiocyanite ions that can inhibit the growth of various oral pathogens, including those responsible for dental caries and periodontal (gum) diseases. Several in vitro and in vivo studies have shown that this enzyme can reduce the proliferation of bacteria such as Streptococcus mutans and Porphyromonas gingivalis, both associated with gum inflammation and periodontitis.

Clinical trials testing toothpastes and mouth rinses supplemented with lactoperoxidase have reported improvements in parameters such as plaque index, gingival bleeding, and microbial load, particularly in individuals with reduced salivary flow or at higher risk for oral infections. However, the magnitude of benefit in healthy adults is still subject to ongoing research, and most studies suggest lactoperoxidase is more effective as a supportive, adjunctive measure rather than a standalone therapy for gum health.

Overall, the use of lactoperoxidase to support gingival (gum) health is scientifically grounded, though not overwhelmingly robust; the evidence base is moderate, warranting a rating of 3 out of 5. Its inclusion in oral care products is justified by its demonstrated antimicrobial activity and its ability to support the mouth's natural defenses.