The relationship between zinc intake and cadmium burden is influenced by smoking status.

A preliminary study by our group suggested that the absorption and accumulation of cadmium may be affected by zinc intake. Tobacco smoke is one major source of cadmium exposure that highly influences cadmium burden among smokers, but it is unclear whether this zinc-cadmium relationship differs by smoking status. The objective of this study was to examine whether the association between zinc intake and cadmium burden differs by smoking status using data from 3900 US adults in the National Health and Nutrition Examination Survey 2007-2012. In an adjusted regression model, dietary cadmium was positively associated with blood and urinary cadmium. There was a significant interaction between zinc intake and smoking status, so we analyzed associations within smoking status subgroups. In an adjusted regression model, zinc intake was inversely associated with urinary cadmium only among non-smokers. Failure to meet the Recommended Dietary Allowance (RDA) for zinc was more common among current smokers than non-smokers, and among those in the highest quintile of blood and urinary cadmium than those in lower quintiles. Zinc intake was inversely associated with urinary cadmium only among subjects meeting the zinc RDA, suggesting that the relationship between zinc intake and cadmium burden differs by smoking status.