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

Abstract

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.

Keywords: dry skin; hyaluronan; ingestion; molecular weight; skin moisture content.

Fig. 1

Changes in the skin moisture with time after ingestion of hyaluronans or the placebo. The skin moisture contents of the right cheek were measured at three points prior to ingestion, 3 and 6 weeks of ingestion, and 2 weeks after ingestion ended. Variations in the skin moisture content relative to the baseline condition (⊿): indicates the placebo group; indicates the HA 800 k group; indicates the HA 300 k group. Dunnett’s test was used to compare the three groups. Data are presented as means ± SE. *p<0.05.

Fig. 2

Changes in the skin viscoelasticity with time following ingestion of hyaluronans or the placebo. The skin viscoelasticity in the right cheek was measured prior to ingestion, 3 and 6 weeks of ingestion, and 2 weeks after ingestion ended. The maximum amplitude value, minimum amplitude value, and the return rate were determined. Variations in skin viscoelasticity relative to the baseline condition (⊿): (A) maximum amplitude value, (B) minimum amplitude value, (C) the return rate. indicates the placebo group; indicates the HA 800 k group; indicates the HA 300 k group. Dunnett’s test was used to compare the three groups. Data are presented as means ± SE. ^†p<0.10.

Fig. 3

Changes in the subjective skin condition with time following ingestion of hyaluronans and placebo. The subjective skin conditions, i.e., luster, suppleness, and wrinkles, were evaluated using a questionnaire prior to ingestion, 3 and 6 weeks of ingestion, and 2 weeks after ingestion ended. Differences in each questionnaire result relative to the baseline condition (⊿): (A) luster, (B) suppleness, and (C) wrinkles. indicates the placebo group; indicates the HA 800 k group; indicates the HA 300 k group. Dunnett’s test was used to compare the three groups. Data are present as means ± SE. ^†p<0.10 and *p<0.05.

Fig. 4

Changes in the skin luster score with time after the ingestion of hyaluronans and placebo. A questionnaire was completed to evaluate the subjective skin luster prior to ingestion, 3 and 6 weeks of ingestion, and 2 weeks after ingestion ended. The number of answers with each score are indicated in the histogram: (A) prior to ingestion, (B) 3 weeks of ingestion, (C) 6 weeks of ingestion, and (D) 2 weeks after ingestion ended.

Fig. 5

Changes in the skin suppleness score with time after the ingestion of hyaluronans and the placebo. A questionnaire was completed to evaluate the subjective skin suppleness prior to ingestion, 3 and 6 weeks of ingestion, and 2 weeks after ingestion ended. The number of answers with each score is indicated in the histogram: (A) prior to ingestion, (B) 3 weeks of ingestion, (C) 6 weeks of ingestion, and (D) 2 weeks after ingestion ended.

Fig. 6

Changes in the skin wrinkles with time score after the ingestion of hyaluronans and the placebo. A questionnaire was completed to evaluate the subjective skin wrinkles prior to ingestion, 3 and 6 weeks of ingestion, and 2 weeks after ingestion ended. The number of answers for each score is indicated in the histogram: (A) prior to ingestion, (B) 3 weeks of ingestion, (C) 6 weeks of ingestion, and (D) 2 weeks after ingestion ended.