Retrospective study revealed that Zn relate to improvement of swallowing function in the older adults

BACKGROUND: Zinc is an essential micronutrient for maintaining biological activity. The level of zinc in the blood is known to decrease with age, especially in those over 75 years of age. In older adults patients with impaired functional status, aspiration pneumonia based on dysphagia often becomes problematic. However, the relationship between zinc deficiency and swallowing function has not been studied before. METHODS: A total of 52 older adults subjects (15 males and 37 females) living in a nursing home were enrolled for this study. At the time of enrollment, data of gender, age, body weight, serum zinc levels, serum albumin levels, and the time in a simple 2-step swallowing provocation test (S-SPT) were collected. In patients with serum zinc levels < 60 μg/dL, we initiated 2 months of oral zinc supplementation therapy with a 34 mg/day zinc load. Those who underwent zinc supplementation were re-evaluated after the treatment period and serum zinc levels and S-SPT time were measured. RESULTS: At the time of enrollment, serum zinc level was significantly correlated with serum albumin levels (Pearson’s R = 0.58, p < 0.0001) and time in the S-SPT (Spearman’s rho = − 0.32, p = 0.0219). Twenty-five of the 52 patients had zinc deficiency with a serum zinc level < 60 μg/dL. After 2 months of oral zinc supplementation, both serum zinc levels (p < 0.0001) and time in the S-SPT (p = 0.04) significantly improved. Meanwhile, serum albumin level (p = 0.48) or body weight (p = 0.07) did not significantly change following zinc supplementation. Zinc supplementation significantly improved swallowing function, especially in the older adults who had comorbid dysphagia and zinc deficiency. CONCLUSIONS: Zinc deficiency is associated with compromised swallowing function in older adults patients with impaired general functions. Oral zinc supplementation can alleviate dysphagia in older adults patients with zinc deficiency even though this is a retrospective study. Further study will be needed to confirm this positive effect. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12877-021-02224-8.