"Is azodicarbonamide really in yoga mats?"

"Yes. ADA is used as a foaming agent in making polyurethane and PVC products, including yoga mats, shoe soles, and other foam rubber products. It's the same chemical used in a completely different industrial context. This is where the 'yoga mat chemical' label came from. The fact that a chemical has multiple uses doesn't automatically make the food use unsafe, but it was effective at drawing public attention to the ingredient."

"Did Subway really remove azodicarbonamide?"

"Yes. In 2014, food blogger Vani Hari (the Food Babe) launched a petition highlighting ADA in Subway's bread. It collected over 50,000 signatures and generated significant media coverage. Subway announced it would remove ADA from its bread. Many other restaurant chains and some supermarket brands followed. The FDA did not require removal."

"What is semicarbazide and why does it matter?"

"Semicarbazide (SEM) is a byproduct formed when ADA breaks down during baking. One animal study found that semicarbazide caused lung tumors in female mice at high doses. The doses were much higher than what would result from eating bread, and the relevance to humans is unclear. But the finding is what drove EFSA's 2005 concern and contributed to the EU's earlier 1997 ban decision."

"Which foods still contain ADA?"

"ADA is still permitted in US commercial bread and flour products at up to 45 ppm. Many supermarket sandwich breads, hot dog and hamburger buns, and dinner rolls still contain it. It's listed by name as 'azodicarbonamide' on ingredient labels. Checking the label is the only reliable way to know."

Azodicarbonamide: The 'Yoga Mat Chemical' in Bread, Explained

Quick Answer

Azodicarbonamide (ADA) is a dough conditioner in commercial bread that makes dough more elastic and easier to handle at industrial speed. ADA itself breaks down almost completely during baking. The concern is semicarbazide, a byproduct of that breakdown, which caused lung tumors in female mice at high doses. The EU banned it in 1997. FDA still allows it at up to 45 ppm.

The Science

In 2014, food blogger Vani Hari published a post about Subway’s bread. The headline called it “yoga mat bread.” Subway had used azodicarbonamide in their bread for years. The same compound is used to make polyurethane foam, including the kind used in yoga mats.

A petition with 50,000 signatures later, Subway removed it.

The reaction was almost entirely about optics. But the underlying chemistry question, what does ADA actually do and is it actually a concern, deserved a more careful look.

What Azodicarbonamide Does in Bread

Azodicarbonamide (often abbreviated ADA) is a dough conditioner. Its job is to modify the protein structure of gluten to make dough easier to work with at industrial speed and scale.

When ADA is added to flour and exposed to moisture, it oxidizes the sulfhydryl groups on glutenin and gliadin proteins. This promotes the formation of additional disulfide bonds between protein chains, strengthening the gluten network. The result is dough that’s more elastic, more extensible, and better able to handle the mechanical stress of high-speed commercial bread production.

Think of raw dough on an industrial bakery line. It needs to stretch without tearing as it moves through rollers and presses. It needs to hold its shape through proofing and maintain gas retention during baking. ADA makes the gluten network more cooperative under those conditions.

Without a dough conditioner, bakers would need higher-protein flour, longer fermentation times, or more careful handling. Those alternatives cost more or slow production.

The Chemistry That Made Regulators Nervous

ADA itself isn’t the main concern. The issue is what happens to it during baking.

ADA is reactive. When bread dough is mixed and baked, ADA breaks down rapidly. The primary decomposition products are biurea (essentially inert and harmless) and semicarbazide (SEM).

Semicarbazide is where the concern lives.

A 2002 study found that semicarbazide caused lung adenomas (a type of tumor) in female mice at high doses. The doses used in the study were substantially higher than what anyone would consume from eating bread. But the finding triggered regulatory action in Europe.

EFSA evaluated ADA in 2005 and concluded that, while the amounts of SEM formed in baked bread were very small, the genotoxicity and carcinogenicity data for SEM couldn’t be dismissed. EFSA did not establish a safe intake level for SEM.

That uncertainty was enough for EFSA to maintain the EU’s existing ban (in effect since 1997, when the EU removed it from approved additives). Australia also prohibits ADA in food.

What FDA Concluded

FDA’s position is different. ADA is permitted under 21 CFR 137.180 at up to 45 parts per million in flour, which works out to 45 mg per kilogram of flour.

FDA’s reasoning: ADA itself breaks down almost completely during baking. The amount of semicarbazide formed in bread from this breakdown is very small, at levels that FDA considers too low to pose a meaningful risk given the doses used in animal studies.

This is a judgment call about dose. The animal study doses were high. The human exposure from bread is low. FDA concluded the gap was large enough that the risk is negligible.

The “Same Chemical, Different Use” Question

The yoga mat comparison is technically accurate. ADA is used as a foaming agent in PVC processing and polyurethane foam manufacturing. The same compound creates the foam structure in some rubber products.

But this framing is misleading about risk. Lots of chemicals have multiple uses. Carbon dioxide is used in fire extinguishers and also carbonates your soda. Ethanol is in hand sanitizer and in beer. The industrial use of a compound doesn’t automatically tell you anything about safety in food.

What matters is whether ADA in bread at permitted levels creates a meaningful risk. The yoga mat comparison gets attention but doesn’t answer that question.

Where It Still Shows Up

ADA was never widely used in European food to begin with, which is partly why the EU ban was relatively painless for the industry there.

In the US, after the 2014 Subway backlash, many major chains and supermarket brands quietly removed ADA or stopped using it in new formulations. But it’s still present in plenty of products.

You’ll still find ADA in some supermarket sandwich breads, packaged buns, dinner rolls, and commercial flour blends. It must be listed by name on ingredient labels.

Artisan breads, sourdoughs, and certified organic bread products don’t use it. The ingredient list is the reliable check.

The Verdict

Caution here comes down to a specific asymmetry. The EU and Australia both found the semicarbazide evidence concerning enough to prohibit ADA, even at relatively low food-use levels. FDA found the dose gap large enough to permit it.

That’s a legitimate scientific disagreement. But the additive serves a function, faster and more consistent commercial bread production, that isn’t hard to replace. Many producers have already done it without any noticeable product quality change.

Choosing bread without ADA is easy. That makes this a reasonable preference even if you weigh the US regulatory position more heavily than the EU’s.

What This Means for You

ADA is listed by name on ingredient labels. Many sandwich bread brands, dinner rolls, and packaged buns still contain it, though several major chains removed it after 2014. Choosing ADA-free bread is easy once you know what to look for. Artisan breads, sourdoughs, and many store-brand organic breads don't use it.