Article at a Glance
- The state of California considers buildings within 500 feet of a freeway to be unsafe for residential use.
- Land that sits within 500-1,000 feet of a highway has been called the “pollution zone.”
- Due to exposure to chemicals like benzene, a volatile organic compound, studies show an increased risk for lung cancer, heart disease and dementia for populations living in close proximity to a freeway.
- Living next to a road that gets in excess of 100,000 vehicles per day poses a similar health risk to living near a freeway. The West Side Highway in Manhattan exceeds 100,000 vehicles per day at certain locations.
- Sulforaphane, and its precursor glucoraphanin, have shown promise in activating the NrF2 pathway, a genetic pathway that turns on our detox genes, such as GSTP1. Broccoli and broccoli sprouts are among the most potent sources of sulforaphane.
- One study in China found that drinking a broccoli sprout derived beverage helped subjects excrete far more benzene than the placebo group. The study authors concluded that eating large amounts of broccoli sprouts was a “frugal” way of detoxifying the body from air pollution.
Here at Gene Food, we are a little obsessed with the NrF2 pathway, a genetic transcription factor responsible for “turning on” over 200 genes, many of which are related to detoxification. As we’ve written about previously, nutrition can play a role in activating NrF2. Because of a compound known as sulforaphane, broccoli sprouts are one of the best NrF2 activators, which is presumably why a growing number of studies have linked consumption of cruciferous vegetables to a reduction in cancer risk.
But this is a post on living in an urban environment, specifically, living close to a highway, so what does broccoli have to do with all that?
In a word, benzene.
Benzene is a volatile organic compound, or “VOC,” that is the byproduct of both cigarette smoke and, you guessed it, automobile exhaust. If you’re living close to a highway, specifically within 500-1,000 feet, you are coming in contact with higher levels of benzene, as well as other dangerous VOCs.
Best not to live within 500 feet of a freeway
In fact, the state of California, in conjunction with scientists at UCLA have recommended that the Golden State stop developers from building schools or residential buildings within 500 feet of a highway as proximity over extended periods of time has been linked to increased risk for a host of diseases, including heart disease, stroke, lung cancer, and dementia. (R)
For example, this study which measured the blood of people living in close proximity to a highway found that inflammatory markers like C-reactive protein and IL-6 were higher in populations that lived next to a freeway, and therefore their risk for heart disease was higher.
Our results suggest that highway proximity affects blood markers of inflammation which are, in turn, associated with increased cardiovascular disease risk.
The LA Times has published a tool for Californians that allows them to measure how close their building is to the nearest freeway. As mentioned above, the 500-1,000 foot range is classified as the “pollution zone,” and it is remarkable how many buildings, many of them “fancy” new developments, fall within the range that is considered unsafe.
Pollution zone: San Diego’s Little Italy neighborhood
For example, a large percentage of San Diego’s nicest downtown neighborhood, Little Italy, is within 1,000 feet of Highway 5, a massive traffic artery that carries hundreds of thousands of cars every day. I measured a new residential building in San Diego’s Little Italy, named after its address at 1810 State Street, to see how close it was to the nearest freeway. The result: 350 feet! To make matters worse, there is an Elementary School directly across the street.
The marketing material for 1810 State says the building is “inspired by SoHo, Chelsea, and the High Line” in New York City, but no disclosures are made about proximity to the highway, and to my knowledge, the building does not have a special air filtration system set up to handle all the pollution.
What about the West Side Highway?
In some sense, the High Line tie in makes sense, as the High Line is adjacent to the West Side Highway, not a major interstate in the traditional sense, but the LA Times tool cautions that “living in close proximity to a road that gets in excess of 100,000 vehicles per day poses a similar health risk to living near a freeway.” I looked it up, and parts of the West Side Highway get more than 100,000 vehicles per day. (R)
Ok, so let’s take this post in a more optimistic direction.
Especially if you’re within 500 feet of a highway, or a road that gets in excess of 100,000 vehicles per day, it is best to move. However, what if you can’t? Or what if you live just outside of the pollution zone and are looking for ways to use food to help your body detox?
Can broccoli help detoxify air pollution?
This brings us back to NrF2. We know that benzene, a nasty VOC, is released into the air from car exhaust.
We know that those living close to a highway or major road are getting exposed to greater levels of benzene.
But we also know that sulforaphane, the compound found in broccoli sprouts I mentioned at the beginning of this post, acts as a cancer chemopreventive agent. For example, this study, which found that sulforaphane inhibited the carcinogenic effect of benzene.
It seems that sulforaphane, by triggering NrF2, helps to turn on genes like GSTP1, which in turn help the body make glutathione, the master detoxifier, which sticks to and removes heavy metals and other bad stuff from our system.
There is even a study out there which looked at broccoli’s ability to detoxify contaminants from air pollution specifically. In a randomized 12 week clinical trial in China, participants were given a “broccoli sprout derived beverage,” with glucoraphanin, a sulforaphane precursor. The subjects lived in an area of China that has problems with air pollution (for those of you have have visited China, you know it is a wonderful place, but air pollution is a huge issue). The group receiving the broccoli sprout beverage excreted much more benzene, presumably because of increased glutathione production.
To quote the study:
Rapid and sustained, statistically significant (P ≤ 0.01) increases in the levels of excretion of the glutathione-derived conjugates of benzene (61%), acrolein (23%), but not crotonaldehyde, were found in those receiving broccoli sprout beverage compared with placebo.
The study authors concluded that eating broccoli sprouts was a “frugal” way of aiding the detoxification of air pollution. For those of you wondering how to get your hands on some glucoraphanin, our product, Cell Shield, contains 230mg of broccoli seed extract, standardized to contain 13% glucoraphanin. Use the coupon code TRYCELLSHIELD for a 10% discount, or just head off the store and load up on raw broccoli and broccoli sprouts.
For more on protecting yourself against air pollution, see our post on air filters.