Effects of Zinc Supplementation in the Elderly with Focus on Muscle Mass, Dry Skin, and Gut Microbiota

Abstract

Background and aim: Zinc is one of the most important essential trace elements found in more than 300 enzymes in humans, and the risk of zinc deficiency has been shown to increase with age. Symptoms associated with zinc deficiency such as muscle weakness, impaired immune function, and delayed wound healing, have much in common with health problems faced by the elderly. However, the relationship between zinc deficiency and the health problems of the elderly has not yet been fully analyzed. Here, we analyzed the effects of zinc in terms of muscle strength, skin barrier function, and gut microbiota in the elderly. Methods: Thirty elderly residents of a special nursing home in Japan were divided into two groups: a zinc intake group (14 participants) and a zinc non-intake group (16 participants). Participants in the zinc intake group received zinc (10 mg/day) for 8 weeks. Changes in muscle mass indices such as calf circumference (CC) and dry skin indices such as stratum corneum water content (SWC) were observed before and after the study. Fecal analysis was also performed at week 8 to analyze the intestinal microflora and short-chain fatty acid (SCFA) content. Results: The values of CC and SWC increased with zinc administration. The analysis of intestinal microflora showed that zinc administration increased the occupancy of Rikenellaceae. This change was observed to be associated with increased CC values. Conclusion: This study suggested that zinc may be involved in maintaining muscle mass in the elderly via the gut microbiota.