Improvement in Skin Conditions by Consumption of Traditional Japanese Miso Soup and Its Mechanism

Abstract

The present study was undertaken to determine the beneficial effects of miso soup consumption on the skin. The women were divided into two groups: the first group consumed three bowls of miso soup per day (miso-consuming group) and the second group consumed three bowls of soup per day without miso (non-miso-consuming group or control group). The women in both groups continued their respective routines every day. Before and after the 2-week trial, the stratum corneum water content, elasticity, sebum amount and skin texture of both their cheek and corner of their eye were analyzed. The skin texture was measured according to the images taken through a digital microscope. The women in the miso-consuming group had a significantly higher the stratum corneum water content, and their skin elasticity and texture improved compared with those in the non-miso-consuming group. There was no significant difference in the sebum amount between the two groups. The questionnaire on individual skin conditions showed that consumption of miso soup tended to improve smooth make-up application. In addition, miso extracts were prepared to examine the effect on ceramide synthesis of epidermal keratinocytes using cultured cells. The findings revealed that miso extracts increased mRNA expression and activity of β-glucocerebrosidase, an enzyme involved in the synthesis of ceramides in the stratum corneum. These results suggest that daily intake of miso soup may improve skin moisture and some ingredients in miso may stimulate the increase of ceramides in the stratum corneum.

Identification of Rice Koji Extract Components that Increase β-Glucocerebrosidase Levels in Human Epidermal Keratinocytes

“…β-GCase activity was determined using 4-methylumbelliferyl β- d -glucopyranoside [ 1 ]. Human keratinocytes cultured for three days in the 96-well plate were washed twice with PBS, and 30 μL of 0.01 mol/L acetate buffer (pH = 5.0) and 40 μL of a 5 mmol/L 4-methylumbelliferyl β- d -glucopyranoside solution were added.…”

“…Rice miso contains many ingredients derived from rice koji and has been a valuable source of nutrition since ancient times. We found that ingesting rice miso improved the moisture content in cheek stratum corneum, skin viscoelasticity, and texture [ 1 ]. Furthermore, the effect of miso extract on ceramide synthesis in epidermal keratinocytes was examined in cultured cells, and the mRNA expression and activity of glucocerebrosidase (β-GCase) in these cells increased when the cells were treated with miso extract [ 1 ].…”

“…We found that ingesting rice miso improved the moisture content in cheek stratum corneum, skin viscoelasticity, and texture [ 1 ]. Furthermore, the effect of miso extract on ceramide synthesis in epidermal keratinocytes was examined in cultured cells, and the mRNA expression and activity of glucocerebrosidase (β-GCase) in these cells increased when the cells were treated with miso extract [ 1 ]. From these results, it was hypothesized that the moisture level of the skin improves by everyday consumption of miso soup made from rice miso and that this may occur via increasing the ceramide content of the stratum corneum [ 1 ].…”

“…Furthermore, the effect of miso extract on ceramide synthesis in epidermal keratinocytes was examined in cultured cells, and the mRNA expression and activity of glucocerebrosidase (β-GCase) in these cells increased when the cells were treated with miso extract [ 1 ]. From these results, it was hypothesized that the moisture level of the skin improves by everyday consumption of miso soup made from rice miso and that this may occur via increasing the ceramide content of the stratum corneum [ 1 ]. A. oryzae produces and secretes many types of enzymes, including α-amylase, which degrades starch; glucoamylase; transglucosidase; acid protease, which degrades protein; and acidic carboxypeptidase [ 2 , 3 ], as it grows.…”

Skin-Moisturizing Effect of Collagen Peptides Taking Orally

“…A good diet is fundamental to improving skin disorders that cannot be resolved with cosmetic products. Consumption of foods that can positively affect the skin, such as collagen peptides [43], hyaluronan [44], N-acetylglucosamine [45], rice-derived glucosylceramide [46], royal jelly [47], and miso [48], are essential for maintaining the internal and/or external beauty of the skin.…”