Abstract
Objective: Firmness and elasticity of skin and sagging skin are great concerns for middle- and advanced-aged women. We conducted an exploratory study on the effectiveness of amino acid mixtures for these issues.
Method: The research participants, 24 women with low levels of skin elasticity measurements (R7) and high levels of a glycative stress marker, skin autofluorescence (SAF), were chosen from 77 potential female participants who were aware of skin deterioration, e.g., loss of elasticity and sagging. The 24 participants were classified into two groups, the His-Thr group and Orn-Thr group (each group: 12 women). Oral ingestions of amino acid mixtures were administrated for 8 weeks, with each group receiving: 1.65 g of His (histidine), 0.8 g of Orn (ornithine) and 1.65 g of Thr (threonine). Effects of skin elasticity, SAF, moisture retention (skin moisture and trans epidermal water loss [TEWL]) and skin color difference were examined after the 8-week oral administration. Both groups, the His-Thr group and Orn-Thr group, showed significant improvements in skin-related subjective symptoms, and indicators of skin elasticity, SAF and TEWL.
Results: The His-Thr group significantly improved lightness assessments (L*) in color difference tests and assessments of dry skin levels by doctors in comparison with the Orn-Thr group. It was judged that there were no safety issues as no adverse events were reported. Furthermore, both groups showed increases in plasma pentosidine concentration. Pentosidine is a product formed in the blood by the reaction of aldehydes with amino acids, peptides, or sugars. During this process, aldehyde modification of proteins can be prevented inside and outside vascular endothelial cells, and therefore it can thought that exogenous amino acids exert a bioprotection effect.
Conclusion: The present study suggested possibilities that amino acid supplementation had favorable effects on the firmness, elasticity, and anti-sagging of skin for middle- and advanced-aged women. His is an amino acid required to maintain homeostasis of filaggrin, which is known for wound healing and moisturizing. We will aspire to conduct and develop further research on the administrations of His and Orn mixtures.
