Vitamin C may offer meaningful protection against one of the world's invisible but pervasive health threats – fine-particle air pollution. New research has found that the common antioxidant can significantly reduce the lung inflammation and cellular damage caused by everyday, low-level exposure to PM2.5.
Scientists from the University of Technology Sydney (UTS) and the Woolcock Institute of Medical Research investigated the effect of vitamin C on lung inflammation and mitochondrial loss triggered by airborne particulate matter (PM) 2.5, the fine-particle air pollution common to urban environments. PM2.5 in outdoor air comes largely from the combustion of gas, oil and diesel, as well as burning wood. Wildfires and dust storms can also cause spikes in the pollution – two events often associated with adverse respiratory issues.
PM2.5 exposure contributes to a suite of health conditions including asthma, chronic obstructive pulmonary disease (COPD), pulmonary fibrosis and even lung cancer. And protection from these fine particles is challenging, given that they're part of the air we breathe.
The scientists used a two-pronged approach in their investigation, testing vitamin C's antioxidant properties on mice and in cell cultures, and found it was able to reduce the negative health effects of low-level PM2.5 exposure.
First, the scientists demonstrated that even at modest levels, PM2.5 triggers an increase in inflammatory cells, elevated cytokines such as IL-1β, TNF-α and IL-17, and a rise in oxidative stress. In mice, mitochondria – the cellular structures most sensitive to pollution-driven damage – became swollen, fragmented and overactive in generating reactive oxygen species. Human lung cells behaved similarly, with reduced viability, higher oxidative stress and the activation of inflammatory pathways associated with chronic respiratory disease.
But in both mice and human cells, vitamin C reduced nearly every effect – inflammatory markers declined, antioxidant enzymes such as SOD2 and GPX4 recovered and mitochondrial structure and function were protected. Interestingly, the supplement stabilized mitochondria, preventing the cascade of oxidative damage that PM2.5 triggers.
“For the first time we are providing hope for a low-cost preventative treatment to a global issue affecting hundreds of millions of people,” said Brian Oliver, a professor in the School of Life Sciences at UTS. “We know now that there is no safe level of air pollution, which causes inflammation in the lungs and leads to myriad respiratory diseases and chronic illnesses, especially in the case of bush fires.”
The dose used in mice corresponded to roughly a gram, or 1,000 mg/day, in humans, which is higher than the recommended daily requirements of around 75 mg/day for women and 90 mg/day for men. However, the safety threshold is considered to be 2,000 mg/day, and many supplements come in 500-mg and 1,000-mg forms. Nonetheless, there's no shortage of foods that offer quality vitamin C (and other nutrients).
The researchers, however, caution against upping vitamin C doses without speaking to your healthcare professional first. While overdose is rare, taking too much can cause unpleasant gastrointestinal side effects, and people with certain health conditions may face other, more serious risks.
“This study suggests that taking the highest permitted dose of vitamin C for you would potentially help, but you would need to speak with your GP 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.”
While the results are promising, they're also preliminary, and more research – including human clinical trials – will be needed to confirm efficacy and safety.
The research was published in the journal Environment International.
Source: University of Technology Sydney
