Vitamin C may reduce harm from air pollution

A new study from the UK shows that adults with asthma and chronic obstructive pulmonary disease (COPD) who have lower levels of vitamin C in their blood are more vulnerable to the harmful effects of air pollution.

To investigate if individual levels of antioxidants and related genetic markers protect against harm from oxidative stress imposed by particulate air pollution, this study examined 209 adults who had been admitted to a hospital for asthma or COPD. Their blood concentrations of vitamins C, E and A, and their levels of particulate matter exposure (PM10) on the day of admission as well as two weeks before and two weeks after admission were compared (1). Participants were grouped by the level of antioxidants in their blood and certain genes that may protect against oxidative stress. The study results showed that PM10 levels were higher on the days prior to hospital admission for asthma or COPD. Smokers and those older than 75 years of age were particularly vulnerable to the effects of air pollution. Participants with low levels of vitamin C in their blood were also more vulnerable to PM10. This effect was not seen with other antioxidants and genes.

The researchers concluded that some people, such as those suffering from pre-existing respiratory diseases and low vitamin C levels, are more susceptible to the harmful effects of air pollution than others. The study results therefore seem to indicate that a healthy diet including fruit and vegetables may protect against the common health threat of air pollution.

One way air pollutants can harm health is through oxidative stress. Harmful oxidant molecules can form when air pollutants are absorbed through the lungs. These oxidants – also called free radicals – roam the body and damage cells. The body constantly tries to combat oxidant molecules with protective antioxidants. If not enough antioxidant molecules are available to cancel them out, oxidative stress can occur. Air pollution can aggravate both asthma and COPD, producing symptoms that can be strong enough to lead to hospitali-zation. Particulate matter (PM) is produced by traffic and combustion of fossil fuels. PM less than 10 micro-meters in diameter, or PM10, is known to exacerbate respiratory illness and increase the risk of heart attacks and other cardiovascular disease.

1. Canova C. et al. PM10-induced hospital admissions for asthma and chronic obstructive pulmonary disease: The modifying effect of individual characteristics. Epidemiology. Published online August 2012.