中高年女性の皮膚性状に対する5—アミノレブリン酸含有食品の改善効果―無作為化二重盲検プラセボ対照並行群間比較試験―

Objective To determine whether orally supplemented 5-aminolevulinic acid（ALA） improves age-related damaged skin properties in healthy middle-aged and older women. Methods This randomized, double-blind, placebo-controlled study included 138 healthy women aged 50-64 years（most women were aged above 55 years） who were bothered about skin dryness. The participants were randomly assigned to receive either placebo or ALA supplement （50 mg ALA phosphate╱day）for 12 weeks and the groups were compared（the primary analysis）. We assessed the effects of ALA supplementation on the stratum corneum hydration （SCH）of the cheek and volar forearm, as well as three skin viscoelasticity parameters measured using a Cutometer®（R2, R5, and R7）on the cheek after 4, 8, and 12 weeks of treatment. Efficacy evaluation was also conducted in 122 selected participants who did not show a conflict with any efficacy analysis exclusion criteria（the secondary analysis）. Results Data from either of the efficacy analyses and both efficacy analyses showed that ALA supplementation increased the SCH levels on the cheek and volar forearm and improved the values of all three skin viscoelasticity parameters on the cheek over the treatment period. Additionally, intergroup differences in the magnitude of changes in the SCH levels at week 12 and the values of R5 and R7 parameters at weeks 8 and 12 significantly favored ALA supplementation. The supplement was well-tolerated, and no clinically problematic side effects or laboratory abnormalities were observed during the treatment. Conclusion Our findings indicate that ALA supplementation is effective for improving skin hydration and skin elasticity in middle-aged and older women. This study is registered with UMIN Clinical Trials Registry（ID: UMIN000030195）