BEIJING, CHINA. Investigations into the causes of chronic obstructive pulmonary disease suggest that a lack of antioxidants may play a role in the development and progression of this disease. It is also known that lung function tends to decline with age. Older people generally move less air through their lungs with each breath than do younger people. A team of American, British and Chinese medical researchers have just completed a major study aimed at determining the role of vitamin C in maintaining lung function. The study involved 3085 Chinese men and women aged 35 to 64 years. The participants' intake of vitamin C was estimated using a three-day weighed household food record and blood samples were also taken and analyzed for vitamin C content. The average (mean) dietary intake of vitamin C was 151.1 mg/day and the mean plasma level was 1.09 mg/dL. It is of interest to note that these values are about 50 per cent higher than values normally found in the United States. The participants also had their lung capacity measured with a spirometer (forced expiratory volume in the first second [FEV] and forced vital capacity [FVC]). After adjusting for sex, age, height, weight, caloric intake, smoking and education the researchers concluded that an increase in vitamin C intake of 100 mg/day corresponded to an increase in FEV of 21.6 mL and an increase in FVC of 24.9 mL. The magnitude of this increase is similar to the age-related decline in lung function during one year of adult life although, of course, opposite in direction.
Hu, Guizhou, et al. Dietary vitamin C intake and lung function in rural China. American Journal of Epidemiology, Vol. 148, September 15, 1998, pp. 594-99