Vitamin C may help those who live in high-traffic areas to protect their lungs
Cities can be exciting places to live, but the concentration of vehicular traffic causes elevated PM2.5, fine particulates, in the air. First of all, there’s no “safe” level of PM2.5. These are so small that they can be inhaled and cause serious health problems, as they can get deep into your lungs and some even get into your bloodstream, according to the EPA. Even “good” air quality days in the city put its residents at risk for COPD and other illnesses.
A new study found that adding vitamin C to our diets actually helps to mitigate damage from air pollution. When our lungs are exposed to PM2.5 pollution, immune cells flood into lungs and trigger inflammation. The particles also damage the cells’ ability to maintain their energy-producing components (mitochondria), leading to a build-up of faulty cellular machinery and harmful stress (reactive oxygen species or ROS). (Vitamin C could protect lungs from air pollution) Our bodies normally produce ROS as a result of the manufacture of cellular energy by mitochondria, and our immune system produces antioxidant enzymes to cancel out the ROS, but additional ROS from PM2.5 pollutants can overwhelm our immune system and cause a cycle of harmful inflammation and damage. The beneficial effects of vitamin C have been attributed to its anti-inflammatory and antioxidant effects.
In the study, mice were exposed to PM2.5 at a rate comparable to a city with generally good air quality. Some of the mice received vitamin C in their drinking water. For those mice, the addition of vitamin C effectively prevented the elevation of total reactive oxygen species (ROS), mitochondrial ROS, and inflammation induced by PM2.5 exposure. The study also followed up with cultures of human cells; when cells were pretreated with vitamin C, it significantly mitigated adverse effects of subsequent PM2.5 exposure on cell viability, inflammatory response, mitochondrial ROS levels, and mitochondrial loss.
PM2.5 is a dangerous pollutant because it is a potent oxidant, a substance that steals electrons from other materials, and which carries poisonous chemicals on its surface, like metals and polycyclic aromatic hydrocarbons (PAH). (Sex-Dependent Responses to Maternal Exposure to PM2.5 in the Offspring) Yet another study showed that uptake of PM2.5 in human in-vitro cells induced cellular oxidative damage, mitochondrial injury, and inflammatory responses. (PM2.5 induces inflammatory responses via oxidative stress-mediated mitophagy in human bronchial epithelial cells)
What does this mean for non-scientists? Even though the US has relatively good air quality on a whole, city-dwellers are still affected by the effects of PM exposure, primarily due to traffic-related air pollution (TRAP). People who reside 50 to 500 m or less from major roadways are more likely to experience chronic low-level TRAP exposure and the resulting negative health impacts. (Sex-Dependent Responses to Maternal Exposure to PM2.5 in the Offspring) Since the production of ROS drives oxidative damage (including the changes to DNA), inflammation and cell death (apoptosis), it is considered to be the primary mechanism by which PM causes respiratory disease. In this study, we showed that short-term PM2.5 exposure at levels consistent with those found in North America, Europe and Australia, resulted in oxidative stress and inflammation. Vitamin C supplementation can boost antioxidative defense and alleviate oxidative stress induced by PM2.5 exposure, suggesting that vitamin C may be used as a preventative strategy to protect the lungs in high-risk populations.
How much vitamin C is appropriate? The study administered vitamin C consistent with the FDA guidelines for starting doses for mice and people: 1.5 g/L in mice translates to approximately 1.1 g/day for a 70 kg adult human—a value that aligns with common high-dose vitamin C supplementation regimens and remains within established safety limits (≤2 g/day, which is 2000 mg/day). The great thing about this is that vitamin C is relatively cheap and available to anyone living in a city or area of high-traffic, and by boosting our immune system, it also helps ward off attacks by other microbes. It’s definitely an easy way to help protect your lungs.
Photo by Larisa Birta on Unsplash
