2021 年 32 巻 2 号 p. 59-65
As Japan enters a super-aging society, there is an urgent need to extend the healthy life span of the elderly. In order to extend the healthy life span, it is essential to prevent physical declines caused by aging. One of the age-related changes is muscle atrophy (sarcopenia). Previous studies have shown that age-related muscle atrophy is caused by a mechanism similar to that of bedridden and weightlessness-induced muscle atrophy. Weightlessness induces oxidative stress and increased expression of the ubiquitin ligase Cbl-b, which induces ubiquitination and degradation of IRS-1 and inhibits IGF-1 signaling, resulting in muscle atrophy. ROS accumulation can be suppressed by antioxidant polyphenols, and Cbl-b can be inhibited by the Cblin peptide (Cbl-b inhibitor) and the anti-ubiquitinating soy protein glycinin. Furthermore, recent studies have shown that morin, a natural flavonoid with potent antioxidant properties, inhibits muscle atrophy induced by dexamethasone (Dex). We propose the usefulness of these functional ingredients and the importance of nutrition for muscle atrophy and aim to devise a nutritional treatment.