How Antioxidant Vitamins Might Buffer Air Pollution
A couple weeks ago, researchers at Columbia published an analysis of lymph nodes from 84 organ donors. These people were all non-smokers, and spanned a wide range of ages, from 11-93. When these tissues were analyzed, the researchers found that inhaled particulate matter seemed to be accumulating in immune cells in lymph nodes associated with the lung.
Remarkably, you can see how these tissues literally blacken over the course of decades, when the tissues are sorted according to the age of the donor.
The team goes on to suggest that this likely weakens the ability of these cells to fight respiratory infections, and could be an underappreciated contributor to the well-established decline of the immune system as people get older.
Ultimately, substantially improving outdoor air quality requires collective action, and it’s kind of hard for individuals to fully control their exposure to pollutants. But there is reason to believe that a healthy diet might help shield our bodies from some of the adverse effects of air pollution. For example, while ambient fine particulate matter (PM2.5) is linked to reduced lung function, those who consume more fruits and vegetables seem to be less strongly affected when living in a polluted environment.
This may be because air pollution wreaks havoc in the body in large part by promoting oxidative stress, which is implicated in a plethora of disease processes. Two new studies, as described below, suggest that strengthening antioxidant capacity through the diet may help combat the free radicals generated by ambient air pollution, lowering biomarkers associated with oxidative stress and inflammation and even limiting risk of going on to develop chronic disease.
This Week's Research Highlights
Chinese researchers recruited 58 healthy young adults from the industrial city of Shijiazhuang, which is one of the most severely polluted metropolitan areas in the country. Participants were randomized in a double-blind fashion to either take vitamin C or a placebo for one week. Then, after a two week washout period, all of them were switched to the opposite condition for another week (so if they took placebo before, they took the vitamin C for the second round, and vice versa). When the subjects took the vitamin C, levels of the antioxidant enzyme glutathione peroxidase were increased by 7.15%. They also showed substantial improvements in biomarkers that are associated with systemic inflammation, including a 19.47% decrease in interleukin-6 (IL-6), a 17.30% decrease in tumor necrosis factor-a (TNF-α), and a 34.01% decrease in C-reactive protein (CRP).
🫐 Higher dietary intake of antioxidant vitamins is linked to protection from the adverse metabolic impact of air pollution exposure.
Researchers analyzed data from a large cohort of UK participants (n=156,490) who were free of type 2 diabetes at the start of the study, and who were followed for almost 12 years. Air pollution exposure was estimated for each participants’ residence through a land use regression model (an algorithm used for analyzing pollution in specific areas).
When the researchers examined dietary data for these subjects, they found that those who had insufficient intakes of antioxidant vitamins, especially C and E, were much more likely to develop type 2 diabetes. However that link was substantially attenuated in people who consumed sufficient antioxidant vitamins. For example, in those who did not meet the recommended dietary intake for vitamin C, the risk of going on to be diagnosed with type 2 diabetes during the study period increased nearly 2.5-fold for every 5 μg/m3 increase in PM2.5. However, in those who consumed enough vitamin C, the risk of developing type 2 diabetes with that exposure rose by just 35%. Similarly, in those who got enough vitamin E, the increase in risk of type 2 diabetes in response to that incremental increase in fine particulate matter exposure was only 9%, versus a 60% increase for those without sufficient vitamin E.
Random Trivia & Weird News
The creation of the Environmental Protection Agency (EPA) in the US was fueled in part by a river catching fire (yeah, really).
Cleveland was a major manufacturing hub for much of the late 19th and 20th centuries. As a result, the Cuyahoga River, which bisects the city, became stagnant and filled with oil, solvents, and industrial waste. An infamous story in Time characterized it as a river that “oozes rather than flows.”
You would think that a river catching fire once would be enough to indicate there was a serious problem, but apparently there were at least 13 fires reported. Finally, shortly after the 1969 fire, the EPA was created through an executive order signed by President Nixon.
Since then, the condition of the river has improved quite a bit (apparently in 2019 federal regulators announced that the fish are even safe to eat, so I guess that’s good)
Podcasts We Loved This Week
- Eric Helms: Plant or animal protein — Rethinking protein and muscle. Via Sigma Nutrition Radio.
- Maryanne Wolf: This is your brain on “deep reading.” Via the Ezra Klein Podcast.
Products We Are Enjoying
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NatureMade is also a very legit company, so you can feel assured that you’re getting what you’re paying for (unfortunately that’s not always the case with supplements).