The association between dietary intakes of zinc, vitamin C and COVID-19 severity and related symptoms: A cross-sectional study

BACKGROUND: The Coronavirus disease 2019 (COVID-19) pandemic has had a devastating impact on health systems, food supplies, and population health. This is the first study to examine the association between zinc and vitamin C intakes and the risk of disease severity and symptoms among COVID-19 patients. METHODS: This cross-sectional study included 250 recovered COVID-19 patients aged 18–65 years from June to September 2021. Data on demographics, anthropometrics, medical history, and disease severity and symptoms were collected. Dietary intake was evaluated using a web-based, 168-item food frequency questionnaire (FFQ). The severity of the disease was determined using the most recent version of the NIH COVID-19 Treatment Guidelines. Using multivariable binary logistic regression, the association between zinc and vitamin C intakes and the risk of disease severity and symptoms in COVID-19 patients was evaluated. RESULTS: The mean age of participants in this study was 44.1 ± 12.1, 52.4% of them were female, and 46% had a severe form of the disease. Participants with higher zinc intakes had lower levels of inflammatory cytokines, such as C-reactive protein (CRP) (13.6 vs. 25.8 mg/l) and erythrocyte sedimentation rate (ESR) (15.9 vs. 29.3). In a fully adjusted model, a higher zinc intake was also associated with a lower risk of severe disease (OR: 0.43; 95% CI: 0.21, 0.90, P-trend = 0.03). Similarly, participants with higher vitamin C intakes had lower CRP (10.3 vs. 31.5 mg/l) and ESR serum concentrations (15.6 Vs. 35.6) and lower odds of severe disease after controlling for potential covariates (OR: 0.31; 95% CI: 0.14, 0.65, P-trend = <0.01). Furthermore, an inverse association was found between dietary zinc intake and COVID-19 symptoms, such as dyspnea, cough, weakness, nausea and vomiting, and sore throat. Higher vitamin C intake was associated with a lower risk of dyspnea, cough, fever, chills, weakness, myalgia, nausea and vomiting, and sore throat. CONCLUSION: In the current study, higher zinc and vitamin C intakes were associated with decreased odds of developing severe COVID-19 and its common symptoms.