Introduction:We examined the effect of 5.0 g/day of collagen peptide (CP) or collagen peptide fermented with Aspergillus sojae (FCP) on skin pigmentation in healthy participants. Methods: In this randomized, double-blind, placebo-controlled study, 44 men and women aged 25-63 years were placed into three groups by stratified random allocation and treated with CP, FCP, or placebo (PL) at 5.0 g/day for 3 months. Their skin condition was measured monthly from baseline to 3 months of intake. Results: No adverse events were identified in any group. The CP group showed a significant reduction in pigmented patches and redness after 1 and 3 months of intake, respectively. In the FCP group, pigmented macules were significantly reduced after 1 month, and pigmented patches after 2 months. Both the allages analysis and the hierarchical analysis below 55 years old yielded similar results. Conclusion: Intake of 5.0 g/day of FCP for 3 months is safe. CP and FCP intake is useful for suppressing pigmentation. In addition, CP intake may be useful for reducing redness. These results suggest a new beneficial effect on the skin of CP supplementation. Trial Registration: UMIN clinical trials registry system, UMIN000040736.

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