Orally administered hyaluronan affects skin dryness and epidermal thickening in photoaged hairless mice.

The oral administration of hyaluronans (HAs) (molecular weight, 300k and less than 10k) to photoaged hairless mice increased the moisture content of the stratum corneum and decreased the epidermal thickness, respectively. Furthermore, orally administered HAs suppressed the low-molecular weight of HA content of the skin. This study indicates oral administered HAs may ameliorate the skin condition resulting from photoaging.

Optimization of dose of collagen hydrolysate to prevent UVB-irradiated skin damage.

Collagen hydrolysate (CH) was orally administered to UVB-irradiated hairless mice at doses of 20, 200-2000 mg/kg BW/day. The low dose of CH increased the skin hydration and reduced the transepidermal water loss on damaged skin. These results suggested the optimal dose of collagen to improve the UV-damaged skin condition.

Oral administration of hyaluronan prevents skin dryness and epidermal thickening in ultraviolet irradiated hairless mice.

Hyaluronan is a component of the extracellular matrix that plays a role in water retention in tissues. In this study, we orally administered hyaluronans of varying molecular weights (300k and less than 10k) repeatedly to hairless mice exposed to ultraviolet (UV) irradiation and examined their effects on the skin of these mice. UV irradiation induces a marked increase in the epidermal thickness of the dorsal skin and a marked decrease in the skin moisture content; however, orally administered hyaluronan, particularly that with a molecular weight of less than 10k, markedly reversed the increase and decrease in the epidermal thickness and skin moisture content, respectively. Furthermore, on analyzing the mice skin, orally administered hyaluronan with a molecular weight of less than 10k increased the levels of the HAS2 gene expression in the skin. Based on these findings, it is assumed that orally administered hyaluronans, with molecular weight of 300k and less than 10k, reversed UV irradiation-induced skin disturbance. In particular, it was considered that the increase in the skin moisture content by orally administered hyaluronan, with a molecular weight of less than 10k, was related to the effect on skin cells.

Herb extracts and collagen hydrolysate improve skin damage resulting from ultraviolet-induced aging in hairless mice.

We examined the effect of the daily ingestion of herb extract from Eucommia ulmoides leaves and Korean ginseng on skin damage induced by repeated UV irradiation of hairless mice. The herb extract was orally administered to mice at a dose of 1000 mg/kg/day. The hydration of mice dorsal skin decreased significantly with repeated UV irradiation, but did not decrease when the herb extract was administered for seven weeks. Transepidermal water loss (TEWL) increased with UV irradiation, but decreased with the administration of dietary herb extract. These effects were more pronounced when combined with the administration of collagen hydrolysate. Geniposidic acid from E. ulmoides leaves and ginsenoside Rg1 from Korean ginseng reduced TEWL and increased the skin moisture content of UV-damaged skin on hairless mice, respectively. We concluded that this dietary herb extract reduced the skin damage caused by UV-induced aging, with geniposidic acid and ginsenoside Rg1 detected in the blood.

Ingestion of hyaluronans (molecular weights 800 k and 300 k) improves dry skin conditions: a randomized, double blind, controlled study.

Hyaluronan (HA) has been increasingly used as a dietary supplement to improve the skin. However, the effect of ingested HA may depend on its molecular weight (MW) because its physiological activities in the body vary with its MW. In this study, we examined the effects of ingested HA with varying MW on the skin. In this randomized, double blind, placebo controlled study, 61 subjects with dry skin received oral HA (120 mg/day), of MWs 800 k and 300 k or placebo, for 6 weeks. The skin moisture contents of the first two groups increased more than those of the placebo group during the ingestion period. In addition, group HA 300 k exhibited significant improvements in skin moisture content 2 weeks after ingestion ended compared with the placebo group. A questionnaire survey about subjective facial aging symptoms showed that the HA treated groups exhibited significantly improved the skin condition compared with the placebo treated group. Furthermore, dermatologists objectively evaluated the clinical symptoms of the facial and whole body skin, showing that no adverse events were related to daily ingestion of HA. This study shows that both of ingesting HAs (MWs 800 k and 300 k) improved the skin condition by increasing the moisture content.

Ingested hyaluronan moisturizes dry skin.

Hyaluronan (HA) is present in many tissues of the body and is essential to maintain moistness in the skin tissues, which contain approximately half the body's HA mass. Due to its viscosity and moisturizing effect, HA is widely distributed as a medicine, cosmetic, food, and, recently marketed in Japan as a popular dietary supplement to promote skin moisture. In a randomized, double-blind, placebo-controlled clinical study it was found that ingested HA increased skin moisture and improved treatment outcomes for patients with dry skin. HA is also reported to be absorbed by the body distributed, in part, to the skin. Ingested HA contributes to the increased synthesis of HA and promotes cell proliferation in fibroblasts. These effects show that ingestion of HA moisturizes the skin and is expected to improve the quality of life for people who suffer from dry skin. This review examines the moisturizing effects of dry skin by ingested HA and summarizes the series of mechanisms from absorption to pharmacological action.

Dietary glucosylceramide enhances tight junction function in skin epidermis via induction of claudin-1.

Dietary glucosylceramide increased the expression of claudin-1 in UVB-irradiated mouse epidermis. Sphingosine and phytosphingosine, metabolites of glucosylceramide, increased trans-epithelial electrical resistance, and phytosphingosine increased claudin-1 mRNA expression in cultured keratinocytes. Our results indicate that the skin barrier improvement induced by dietary glucosylceramide might be due to enhancement of tight junction function, mediated by increased expression of claudin-1 induced by sphingoid metabolites.