Serum levels of copper but not zinc are associated with head and chest cold in the NHANES.

BACKGROUND: Common colds are among the top reasons why children miss school and adults miss work. The Centers for Disease Control and prevention estimates that there are millions of cases of the common cold in the United States each year. The essential trace elements zinc and copper have immunomodulatory functions, and zinc has been reported to reduce the general risk of infection, whereas the copper-to-zinc ratio has been associated with an increased risk of incident infections in middle-aged men. Studies involving these two trace elements are generally scarce and were often limited to men.

MATERIAL AND METHODS: We used data from the National Health and Nutrition Examination Surveys (NHANES) to examine potential associations between head or chest cold events and serum levels of copper and zinc in n = 2795 NHANES participants enrolled between 2011 and 2016.

RESULTS: Comparing participants with and without an event of head or chest cold in the last 30 days, no significant differences were found in the serum levels of both trace elements. Notably, copper levels tended to be slightly higher in participants with a recent infection (121.56 (2.69) µg/dl) as compared to participants without infection (117.755 (1.04) µg/dl; p = 0.119). In multivariate logistic regression models adjusting for confounders, copper levels were significantly associated with increased odds for a previous head/chest cold (OR: 1.93 (CI: 1.07-3.47), p = 0.028). Notably, no significant associations were found for zinc and the copper-to-zinc ratio.

CONCLUSIONS: Elevated copper levels were associated with head and chest cold events in the past 30 days. Whether elevated copper levels reflect a pro-inflammatory infection-predisposing status or whether they were elevated subsequent to the infectious event in some individuals in the sense of a reversed causality remains subject to future research.