Ingested hyaluronan moisturizes dry skin

Abstract

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.

Figure 1

The structure of hyaluronan.

Figure 2

Skin moisture content changes by HA (MW: 8 × 10⁵) ingestion or placebo. 39 female subjects were randomly divided into two groups (HA group, n = 19; placebo group, n = 20) to minimize the inter-group differences in skin moisture content, skin elasticity and age. The skin moisture content at the lower part of the left eye was measured using a Corneometer® CM 825 before the control period, before the ingestion, and after 3 and 6 weeks of the ingestion. ■ indicates HA; □ indicates placebo. An unpaired t-test was used to compare the two groups. Data are presented as mean ± S.E. Asterisks indicate a statistically significant difference, *p < 0.05.

Figure 3

Skin moisture content is changed by HA (MW: 3 × 10⁵) ingestion or placebo. 42 female subjects were randomly divided into two groups (HA group, n = 20; subjects placebo group, n = 22) to minimize the inter-group differences in skin moisture content and age. The skin moisture content at the cheeks were measured with a Corneometer® CM 825 before the ingestion, after 3 and 6 weeks of the ingestion, and 2 weeks after the end of ingestion. Variations in the skin moisture content relative to baseline level are shown. ■ indicates HA; □ indicates placebo. An unpaired t-test was used to compare the groups. Data are presented as mean ± S.E. Asterisks indicate a statistically significant difference, *p < 0.05.

Figure 4

Metabolic pathway of ingested hyaluronan.