Although many natural remedies are based more on intuition than science, a surprisingly rigorous set of studies from different research labs is finding that eating broccoli helps our bodies fight the effects of air pollution.
Scientists have isolated the compound thought to help the body remove pollutants like benzene and fight inflammation. The compound, sulforaphane, is in broccoli, cauliflower, and other vegetables.
Placebo-Controlled Studies Find Health Benefits
In one study, researchers from Johns Hopkins School of Medicine randomly assigned 291 rural residents of Qidong, Jiangsu to drink a broccoli sprout drink or a placebo drink for 12 weeks. Because of the heavy industry in their area, Qidong residents breathe high levels of pollutants like benzene. Compared to residents consuming the placebo drink, residents drinking the broccoli sprout drink passed significantly more benzene out through their urine.
The findings span different labs and countries. Researchers in Milan randomly assigned smokers to eat a portion (250g) of steamed broccoli or a placebo diet for 10 days. On the days when they ate broccoli, the smokers had significantly lower levels inflammation markers in their blood, which is known to be triggered by air pollution.
A team of researchers in California had participants breathe diesel exhaust equivalent to spending a day on the freeway in Los Angeles. Beforehand, researchers randomly assigned some participants to eat broccoli sprout extract equivalent to about 150 grams of broccoli. The bodies of people who had eaten broccoli extract experienced a much less severe inflammation reaction to the pollution, as measured by their white blood cell count.
A Checkered Past for Claims About Plants
Critical readers would be justified in being skeptical of claims behind natural cures for air pollution. I’ve written about people who make large claims about plants cleaning indoor air. In this area, claims are large and evidence is sparse.
For some, the motivation may be the general belief in natural cures, such as with this popular TED talk, which claims that a few potted plants can produce spectacular reductions in lung symptoms.
For others, the allure may be money, such as the people behind this plant pot, which the makers claim reduces pollutants by 75%. The makers’ Kickstarter campaigned netted 106,000 Euros, and they now sell the pot for about 80 Euros a piece.
The Airy potted plant press photo and explanatory diagram
Yet tests in real-world conditions have found little or no effects of plants. Smart Air conducted real-world tests of the effect of plants on PM2.5 levels in a Beijing apartment and found no effect.
I’ve written about the tests of a team of citizen scientists who tested whether an army of plants could reduce formaldehyde levels in an office room. Levels of formaldehyde went up during their test.
Most studies that find evidence of plants on pollution were conducted in small sealed containers surrounded by growing lights, such as the famous NASA plant study (although there are exceptions). Those conditions are nothing like normal people’s homes.
Yet against this backdrop of skepticism, the scientific evidence for broccoli is surprisingly well established. And contrasted with the $2,000 imported air purifiers on the market, the researchers of the study in China noted that broccoli sprouts offer “a frugal means” to reduce the health effects of air pollution.
Five Foods That Help Your Body Fight Air Pollution
These five foods contain air-pollution-fighting sulforaphane.
1. Broccoli – simple and easy to find
2. Broccoli sprouts – harder to find, but contain 10 times or more sulforaphane than broccoli
3. Brussel sprouts
4. Red cabbage
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Thomas is an Associate Professor of Behavior Science at the University of Chicago Booth School of Business and the founder of, a social enterprise to help people in China breathe clean air without shelling out thousands of dollars for expensive purifiers.