- A study led by the University of Technology Sydney found that high doses of vitamin C may help protect lung tissue from the harmful effects of air pollution, particularly, PM2.5 — a fine particulate matter.
- In experiments with mice and human airway cells, vitamin C reduced both inflammation and oxidative stress caused by pollution exposure.
- Researchers caution that the effective dose observed in the study is significantly higher than daily recommendations—roughly the equivalent of 15 oranges a day—and should only be taken under medical guidance.
According to the European Environmental Agency, air pollution is the “single largest environmental health risk in Europe and a major cause of premature death and disease.” In 2023, it accounted for more than 180,000 premature deaths across the European Union alone. In that same year, the agency estimated that 94.4% of the urban population was exposed to concentrations of fine particulate matter “above the health-based guideline level set by the World Health Organization.” So yes, air pollution is a problem. But according to recent research, the answer could be found inside a juicy orange.
In December, researchers led by a team from the University of Technology Sydney published findings from their study examining how high doses of vitamin C may interact with lung tissue exposed to “fine particulate matter,” aka pollution.
To find out, the team collected real-world fine particulate matter, known as PM2.5, which measures 2.5 micrometers or less in diameter (about 30 times smaller than the width of a human hair) from the air above a high-traffic road in Sydney’s central business district.
They brought it back to their lab, where they exposed mice to the equivalent of a “low-level” daily dose of pollution for three weeks and also dosed human bronchial epithelial cells (an airway cell). Then, they added vitamin C, with some mice receiving it in their drinking water throughout the exposure window (1.5 grams of vitamin C per liter of water), and some cells pre-treated with it before they were exposed to the vitamin C particles (200 micrograms per milliliter).
From there, the researchers tracked all changes that might indicate early lung stress—such as immune cells flooding the airways, inflammation, or oxidative stress. And they found that large doses of vitamin C may indeed provide some protection.
“Antioxidant vitamin C supplementation was effective in mitigating the adverse effects of low-level PM2.5 exposure, which may be recommended to high-risk individuals,” Xu Bai, a UTS graduate student and author on the paper, said in a statement.
Vitamin C protected in a number of ways, the team reported, including reducing harmful inflammation and preventing oxidative stress. However, the caveat is that they really mean it when they say “high dose” of vitamin C. For context, the amount given to mice equates to about 1.1 grams (1,100 mg) per day for a 154-pound adult human. And because a standard orange has about 70 milligrams of vitamin C, that works out to about 15 to 16 oranges a day.
It’s also far higher than the typical recommended dose. As the Mayo Clinic explains, “The recommended daily amount of vitamin C is 90 milligrams for adult men and 75 milligrams for adult women. If you take vitamin C for its antioxidant effects, the supplement might not be as good for you as natural vitamin C that’s in food.”
Still, the authors note, these findings are a great jumping-off point for understanding the correct doses of specific vitamins that could protect humans against pollution.
“This study suggests that taking the highest permitted dose of vitamin C for you would potentially help,” Brian Oliver, a molecular biologist at UTS, added. “But you would need to speak with your [general practitioner] to make sure you’re taking the right kind of supplement at the right levels and don’t accidentally overdose on something else included in an over-the-counter supplement.”
As Oliver added, there is no safe level of air pollution, but he added that “For the first time, we are providing hope for a low-cost preventative treatment to a global issue affecting hundreds of millions of people.”
