Subway Bread Will Not Give You Cancer


Earlier this year Vani Hari who runs the blog FoodBabe began an online petition for Subway to remove an ingredient from their bread called azodicarbonamide or ADA for short.  She makes statements like ADA is a component used to make yoga mats, it causes respiratory issues, and when heated ADA is linked to tumor development and cancer.  Major news networks like CNN and USA Today picked up the story and ran with it, pretty much citing these claims verbatim.  It becomes much less interesting when you actually look into the details but the news and people like Vani make their living by fear mongering and sensationalizing pseudoscience.  I find it detestable.

First, ADA is a bleaching agent used in flour and helps to make the dough in bread more hardy.  It’s not just Subway that uses it in their bread.  It’s everywhere; from other restaurants like McDonalds and Starbucks to Pillsbury and Sara Lee at the grocery store.

But aren’t we still eating yoga mat material?  Sure, but lots of foodstuff and chemicals are used interchangeably between food and other materials.  Calcium chloride is used in canned vegetables, beer and sports drinks but its also used in plastics and concrete mix.  Dihydrogenated tallow dimethyl ammonium chloride comes from animal fat and is used in fabric softeners.  Glue is also made from animal fat.  Starch derivatives are used as a binding agent to make coated paper, but we’re not calling for a ban on potatoes, which are a source of starch.

To say we’re eating yoga mat material with Subway bread is complete hyperbole in order to draw a reaction from people.  It’s like saying hydrogen is poisonous to humans, so don’t drink water.

The next claim was that ADA causes respiratory issues.  This is actually true and the information comes from a report by the World Health Organization (WHO).  If you actually look at the report though, it states that this affect was only observed in people who worked with industrial sized quantities of pure ADA.  If you work with large quantities of anything that could be inhaled, its likely going to cause respiratory irritation because, surprisingly, the only thing meant to go into your lungs is air.  Going back to my previous example of calcium chloride, look at a material data safety sheet for a chemical such as this one, and you’ll see that its listed as a skin, eye and respiratory irritant.  ADA wasn’t even classified as a skin irritant in the WHO report.  There is absolutely NO WAY you could draw a link between eating bread and respiratory issues if you actually read the article that Vani herself cites.

The final claim that ADA can cause cancer is more hyperbole.  ADA acts as an oxidizing agent in bread and forms biurea, a harmless compound that when ingested is rapidly excreted in the urine. But it can also form semicarbazide as a secondary product of heating ADA.  Semicarbazide has been shown to increase the incidence of lung cancer in mice that were given a high concentration of the chemical in the drinking water, but the untreated mice were also getting cancer in this study.  However, another study involving rats found semicarbazide did not cause cancer even in the 1000ppm exposure range and it has not been found to damage DNA in vivo.

Actually, trace amounts of semicarbazide have been found in cooked crayfish and fresh water shrimp…I wonder where the “shrimp causes cancer” people are.

Let’s do some numbers.  The FDA regards ADA as a safe food additive and allows 45 ppm (parts per million 0.0045%) of ADA in flour, which translates to 2.05 grams per 100 pounds of flour.  According to the average foot long sub, toppings included, ranges from 450-500 grams.  So I’m going to say the bread alone in a foot long sub weighs about 200 grams, which would contain 0.009 grams of ADA.  200 grams is a good number because the amount of semicarbazide has already been determined by the European Food Safety Authority to be around 28 ppb (parts per billion), as an aside that same study concluded that the amount of semicarbazide exposure from food is minimal and is not considered a risk.   Anyway, that works out to be 0.00056 grams, or 0.00028% of semicarbazide in a footlong sub.   You would have to eat 215 footlong subs in one sitting to even receive one dose equivalent to what the mice received in the cancer study.  Keeping in mind that those mice were predisposed to cancer and took that dose consistently over 6 weeks.  Even Jared isn’t eating that many Subway footlongs.

In other words, its a very very miniscule amount of both compounds.  Anything in abundance is going to have negative results and nearly anything has the potential to cause cancer if you provide the perfect environment.  For example an excess of antioxidants like Vitamin E could increase the risk of cancer and speed the progression of cancer.

Unfortunately for Subway, they were forced to remove the additive from their bread.  Its a much easier form of damage control than it is to try to educate the public on the negligible risk of a compound they can’t even pronounce, and the pseudoscience fear mongers win.  I assume the 500 other products out there containing ADA will be looking to lay low and hope the PR storm passes or be forced to phase out ADA as well.


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  1. #1 by Linda on March 27, 2014 - 10:20 AM

    Wow, Thanks for the interesting info! This helps a lot!

  1. The Food Babe and other nonsense | Scripturient: Blog & Commentary

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