Increased zinc intake linked to reduced risk for obstructive lung disease
MedWire News: Individuals with a high intake of zinc are less likely to develop obstructive lung disease than those with a low intake of the mineral, regardless of smoking status, research suggests.
Writing in the journal Respiratory Research, Jou-Wei Lin (National Taiwan University Hospital, Dou-Liou City, China) and colleagues explain that previous studies have indicated that exposure to cadmium, a constituent of cigarette smoke, is associated with oxidative stress and chronic inflammation, and may play a part in the development of obstructive lung disease.
As zinc may reduce cadmium toxicity, the researchers investigated whether zinc intake was associated with obstructive lung disease prevalence in 8745 individuals, aged 40 years or older, who participated in the National Health and Nutrition Examination Survey 1988–1994 (NHANES III).
Zinc intake, including the use of supplements, was assessed using nutritional questionnaires.
Gender-, ethnicity-, and age-specific equations were used to calculate lower limit of normal (LLN) values for FEV1 and the FEV1/forced vital capacity (FVC) ratio, with the presence of obstructive lung disease defined by values below the LLN.
Analysis revealed that individuals in the lowest (less than 8.35 mg/day) and middle (8.35–14.4 mg/day) tertiles for zinc intake were 1.29 and 1.89 times, respectively, more likely to have obstructive lung disease than those in the highest tertile (more than 14.4 mg/day), after adjustment for confounding factors.
Furthermore, participants in the lowest tertile for zinc intake had the greatest risk for obstructive lung disease regardless of smoking status.
The researchers also found that the effect of smoking on lung function fell significantly after adjustment for urinary cadmium.
Lin and team conclude: “The current study demonstrated that [increased] zinc intake is associated with a lower risk of developing smoking-associated obstructive lung disorder for smokers and non-smokers alike. The interplay between zinc and cadmium presumably plays a role in mediating the toxic effect of smoking.”
However, they add: “Although zinc intake is associated with lower risk of obstructive lung disease, the risk reduction associated with smoking cessation or never smoking is much greater. Thus, smoking prevention and cessation programs should remain a cornerstone of public health policy to reduce the subsequent risk of obstructive lung disease.”
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By Mark Cowen