A study demonstrated the effectiveness of apple polyphenols in inhibiting facial skin pigmentation induced by UV irradiation in healthy women (aged 20-39 years) taking apple polyphenol supplements orally for 12 weeks. It was shown to reduce the formation of superoxide radicals and protect against the oxidative stress suggesting a powerful antioxidant activity, which resulted in the inhibition of melanogenesis (dark brown pigment production) caused by UV irradiation.
The major active compounds in the apple polyphenols are procyanidins found abundantly in foods such as fruits, vegetables, nuts, seeds, red wine and cocoa as well as grape seeds and pine barks. Apples are an important source of procyanidins. The apple polyphenols used in this trial were extracted from juice of unripe apples.
Interestingly, the absorption of procyanidins in the small intestine is very low, but most of the administered procyanidins have been shown to be degraded in the large intestine by the gut microbiota. It has also been shown previously that procyanidins were associated with a change in the gut microbiota resulting in a decrease in the Firmicutes/Bacteroidetes ratio, which contributed to the prevention of obesity and diabetes in mice fed a high-fat diet.
Reference:
Shoji, T et al. (2020) Administration of apple polyphenol supplements for skin conditions in healthy women: A randomised, double-blind, placebo controlled clinical trial. Nutrients. 12(4): 1071.