Serum antioxidant status and mortality from influenza and pneumonia in US Adults

Abstract

BACKGROUND AND AIM: Some research suggests that antioxidant supplementation may alleviate the severity of viral respiratory infections, but the evidence from prospective population studies is limited. We examined the prospective association between serum antioxidant status and mortality from influenza and pneumonia using data from the US National Health and Nutrition Examination Survey (NHANES)-III. METHODS: We included 7428 NHANES-III participants ≥45 years of age and their data on serum concentrations of the antioxidants vitamin C, vitamin A, vitamin E, total carotene (α- and β-forms), β-cryptoxanthin, lutein+zeaxanthin, and lycopene. We also computed total antioxidant capacity (TAC) as a measure of composite antioxidant status in serum. Survey-weighted Cox proportional hazard models were used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) comparing quartiles of each antioxidant and TAC. RESULTS:With a weighted-median follow-up of 16.8 years, 154 participants died from influenza/pneumonia (weighted incidence rate=0.88 per 1000 person-years). After adjustment for sex, race/ethnicity, phase, education, cholesterol, body mass index, and smoking history, serum vitamin C, total carotene, and TAC were non-linearly associated with influenza/pneumonia mortality, with the statistically significant smallest HRs at the third quartile vs the first quartile [HRs=0.32 (95% CI: 0.15–0.67), 0.25 (0.14–0.45), and 0.24 (0.11–0.51), respectively]. HRs comparing the fourth vs the first quartiles were weaker and non-significant: 0.56 (95% CI: 0.26–1.18), 0.68 (0.40–1.17), and 0.63 (0.30–1.34), respectively. Serum lycopene had a monotonic association with influenza/pneumonia mortality [HR=0.45 (95% CI: 0.24–0.85) comparing the fourth vs the first quartile, P-for-trend=0.01]. No statistically significant associations were found for other antioxidants. CONCLUSIONS:This study suggests that antioxidant intake may reduce mortality risk from influenza or pneumonia in the US general population. These findings warrant further research, including investigations that can address whether antioxidant intake can blunt the risk of mortality from COVID-19. KEYWORDS: Food/nutrition, infectious diseases, mortality, respiratory outcomes