Polyphenols are a diverse group of naturally occurring compounds found in plants, known for their antioxidant and anti-inflammatory properties. Their use to support gum (periodontal) health is primarily supported by scientific research, especially in vitro and animal studies, as well as some small human trials. Polyphenols from sources like green tea, cranberries, and pomegranate have been shown to inhibit the growth of pathogenic oral bacteria (such as Porphyromonas gingivalis and Streptococcus mutans), reduce inflammation, and decrease oxidative stress in gum tissues. These actions can help limit progression of gingivitis and periodontitis.

Several clinical studies have indicated that mouthwashes or toothpastes containing polyphenol-rich plant extracts may reduce gingival bleeding, plaque accumulation, and markers of inflammation compared to placebo. However, most studies use specific polyphenols or extracts, not a generic or "unspecified" polyphenol source. The evidence is promising but not yet conclusive due to variability in study design, polyphenol source, dosage, and duration.

In summary, there is moderate scientific evidence that polyphenols can support gum health, primarily by modulating the oral microbiome and reducing inflammation. More robust, long-term human studies with standardized polyphenol preparations are needed to confirm efficacy and optimal use.