High plasma vitamin C concentrations reduce risk of incident respiratory diseases, mortality
Higher levels of vitamin C concentration as an indicator of high fruit and vegetable intake correlate with a lower risk of cancerous and noncancerous respiratory illnesses, including nonsmoking-related cancer incidence and deaths, according to a study.
During follow-up (>300,000 person-years), a total of 3,914 incident events and 407 deaths occurred due to any respiratory diseases (excluding lung cancers), as well as 367 incident lung cancers and 280 lung cancer deaths.
Individuals in the top quartiles of baseline plasma vitamin C concentrations had a 43-percent lower risk of lung cancer (hazard ratio [HR], 0.57; 95 percent CI, 0.41–0.81) compared with those in the bottom quartile, independently of potential confounders. There were similar results for any noncancerous respiratory diseases (HR, 0.85; 0.77–0.95), including chronic respiratory diseases (HR, 0.81; 0.69–0.96) and pneumonia (HR, 0.70; 0.59–0.83).
The corresponding HRs for mortality were as follows: 0.54 (0.35–0.81), 0.81 (0.59–1.12), 0.85 (0.44–1.66) and 0.61 (0.37–1.01). When limiting analyses to nonsmokers, there were 42 percent and 53 percent decreases in risks of nonsmoking-related lung cancer incidence and death, respectively.
This study included 19,357 men and women aged 40–79 years without prevalent respiratory diseases at baseline (1993–1997) and participating in the European Prospective Investigation into Cancer (EPIC)-Norfolk study in the United Kingdom. Participants were followed through March 2015 for both incidence and mortality from respiratory diseases.
“Cancerous and noncancerous respiratory diseases are common and contribute significantly to global disease burden,” the authors noted.