Effect of fermented soybeans "natto" containing collagen peptide on human skin in vivo

Objectives: In the present study, we investigated the influence of fermented soybeans "natto" containing collagen peptide on human skin in vivo. Methods: Twenty-two healthy subjects (22 females, from 40 to 54 years old) were divided into two groups, i.e., the group that took fermented soybeans "natto" containing collagen peptide (11 subjects) and the group that did not take them so that there was no bias in the age or the questionnaire scores of each group. The former group took 50 g of fermented soybeans "natto" (containing collagen peptide) and sauce (containing collagen peptide) for fermented soybeans "natto" once daily for 9 consecutive weeks. Results: It was found that in the group that took fermented soybeans "natto" containing collagen peptide, the subjective symptoms of skin moisture, smooth feeling, skin luster, smooth application of makeup and the general condition of the skin were significantly improved from 2 weeks of intake, skin texture was improved from 3 weeks of intake, and skin softness, nail hardness, etc. were improved from 6 weeks of intake, compared with the pre-intake condition; in weeks 6 and 9 of intake, the water content in the stratum corneum was significantly increased, in weeks 3, 6 and 9 of intake, skin elasticity was significantly increased, while in week 6 of intake, skin softness was significantly increased, compared with the pre-intake condition; in the group that did not take them, however, did not show a significant improvement or a significant increase. Conclusions: The findings presented above suggest that fermented soybeans "natto" containing collagen peptide have favorable influences on the skin.