Breathing in the city is not trivial: seemingly clear air can contain invisible particles which attack the bronchi on a daily basis. Many then wonder if a simple tablet of
vitamin C can really limit the damage of the
air pollution. The idea is circulating, the evidence is more recent.
An Australian team has just published in Environment International a study which provides concrete elements. By exposing mice and human lung cells to low doses of fine particles PM2.5then by testing vitamin C intake, researchers observed a measurable protective effect. But can we talk about a real solution to air pollution?
Air pollution: a risk without threshold for the lungs
The authors point out that prolonged exposure to
PM2.5 is a major risk factor for chronic diseases such as asthma, COPD, pulmonary fibrosis or certain lung cancers. According to them, there is simply no risk-free exposure threshold to PM2.5, and the effects of low concentrations, such as those observed in Europe or North America, remain largely underestimated.
According to Global Burden of Disease data, air pollution has become the second leading preventable health risk factor, ahead of tobacco use. In 2019, it is estimated to have contributed to more than 200 million years of healthy life lost. For Professor Brian Oliver of the University of Sydney, “We now know that there is no safe threshold for air pollution. This causes inflammation of the lungs and leads to a multitude of respiratory diseases and chronic conditions, particularly in the event of fires.“.
What does the study show on vitamin C and fine PM2.5 particles?
To study the impact of low pollution, researchers exposed 6-week-old mice daily to 5 micrograms per day of particles from Sydney road traffic for three weeks. At the same time, a group received
vitamin C in drinking water, another only saline solution. They reproduced this pattern on human epithelial cells, also placed in contact with realistic doses of PM2.5.
Without supplementation, this exposure triggered marked oxidative stress, loss of functional mitochondria, and infiltration of inflammatory cells in the mice’s lungs, while the viability of human cells fell. With the contribution of vitamin Cthese effects were significantly attenuated: write the researchers, “Taking vitamin C significantly attenuated the adverse effects of PM2.5 exposure on cell viability, inflammatory response, mitochondrial levels“. The mitochondria played their role as “energy plants” better and the markers of inflammation declined.
Vitamin C against pollution: hope, limits and precautions
For Brian Oliver, these results offer a strong perspective: “For the first time, we offer hope of inexpensive preventative treatment for a global problem that affects hundreds of millions of people“. The doses tested in mice correspond to approximately 1,000 mg of vitamin C per day in adults, much more than the usual intake, but still below the safety threshold of 2,000 mg per day mentioned by the authors.
However, researchers remain cautious: their data comes mainly from animal and cellular models, and there is no proof that a supplement erases the effects of air very laden with fine particles. They warn against the use of freely available supplements, sometimes rich in several vitamins. Their message is explicit, warns Brian Oliver: “It is essential to consult your doctor to ensure that you are taking the right type of supplement at the right dosage.“. Excessive consumption of vitamin C can also cause digestive problems.