Effect of Continuous Intake of Onion Powder on Oxidative Stress Biomarkers and Skeletal Muscle Maintenance in Elderly Bedridden Individuals:A Pilot Study

The number of bedridden elderly is substantially increasing in our aging society. Bedridden patients experience muscle atrophy due to prolonged inactivity. We are concerned about whether the antioxidative flavonoid quercetin can prevent disuse muscle atrophy in elderly people considering that oxidative stress plays a role in this condition. This study explored the links between quercetin intake, oxidative stress, and muscle preservation in bedridden individuals. Onion was selected and a dose of 5 g of onion powder, which contains 99.7 mg of quercetin aglycone equivalent, was given to patients who were bedridden for 30 days. Plasma quercetin concentration was significantly increased in the onion powder group, with regular intake of quercetin meals maintaining high plasma levels (n=9). Higher plasma quercetin levels were linked to lower plasma oxidized low-density lipoprotein (ox-LDL) and urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) content. No correlation was identified in the indexes of muscle maintenance (volume of the quadriceps femoris muscle) and the minimum necessary activities of daily living (ADL). In conclusion, our small-scale pilot study involving bedridden individuals did not demonstrate a positive effect of continuous quercetin intake on the prevention of muscle atrophy. However, efficient dietary quercetin consumption can mitigate the elevation of in vivo oxidative stress. J. Med. Invest. 72 : 324-329, August, 2025.