Abstract
Antioxidant (AOX) deficiencies are commonly observed in older adults and oxidative stress has been suggested to contribute to sarcopenia. Here we investigate if 1) low levels of dietary antioxidants had a negative impact on parameters of muscle mass, function and quality, and 2) to study if nutritional interventions with AOX and/or leucine-enriched whey protein could improve these muscle parameters in aged mice. 18-months-old mice were fed a casein-based antioxidant-deficient (lowox) diet or a casein-based control-diet (CTRL) for 7 months. During the last 3 months, lowox-mice were subjected to either: a) continued lowox, b) supplementation with vitamin A/E, Selenium and Zinc (AOX), c) substitution of casein with leucine-enriched whey protein (PROT) or d) a combination of both AOX and PROT (TOTAL). After 7 months lowox-mice displayed lower muscle strength and more muscle fatigue compared to CTRL. Compared to lowox-mice, PROT-mice showed improved muscle power, grip strength and less muscle fatigue. AOX-mice showed improved oxidative status, less muscle fatigue, improved grip strength and mitochondrial dynamics compared to lowox-mice. The TOTAL-mice showed the combined effects of both interventions compared to lowox-mice. In conclusion, nutritional intervention with AOX and/or leucine-enriched whey protein can play a role in improving muscle health in a AOX-deficient mouse model.
Highlights
During the ageing process, muscle mass, strength and function decline, defining sarcopenia [1]
This study clearly demonstrates the occurrence of lower maximal muscle strength and more muscle fatigue when mice were fed a diet low in antioxidants vitamin A, vitamin E, Selenium and Zinc compared to control mice of the same age
We showed that the impaired muscle quality linked to poor antioxidant intake during ageing can be improved by nutritional intervention in which dietary casein protein is substituted with a leucine-enriched whey protein source
Summary
Muscle mass, strength and function decline, defining sarcopenia [1]. Contributors to sarcopenia are multi-factorial: decreased levels of physical activity, increased levels of oxidative stress, pro-inflammatory status, endocrine changes, anabolic resistance, and inadequate nutrition [1]. In addition to muscle mass and strength, another determining factor of muscle function is muscle power. Muscle power is strongly associated with gait speed [3], balance [4] and functional status [5]. Muscle power has been found to be more relevant than muscle strength for many tasks of daily living [5,6]. The decline of muscle mass, strength and power suggests a progressive worsening of muscle quality during ageing or in other words the decreased capacity of the muscle to adapt to its environment [2]
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