Vitamin c and vitamin d show moderate evidence for reducing the risk of contracting upper respiratory infections (URTIs) as well as reducing the duration of URTI symptoms,[1] although only vitamin D has been shown to lower risk of the flu specifically.[2]
References
- ^Ajibola Ibraheem Abioye, Sabri Bromage, Wafaie FawziEffect of micronutrient supplements on influenza and other respiratory tract infections among adults: a systematic review and meta-analysisBMJ Glob Health.(2021 Jan)
- ^Zhixin Zhu, Xiaoxia Zhu, Lanfang Gu, Yancen Zhan, Liang Chen, Xiuyang LiAssociation Between Vitamin D and Influenza: Meta-Analysis and Systematic Review of Randomized Controlled TrialsFront Nutr.(2022 Jan 7)