Meet the movement making companies show you what they're made of.

Do you remember hearing something about Subway and yoga mats back in 2014?

It's the kind of story that really stands out. In January 2014, health blogger Vani Hari wrote about her discovery that the bread used in Subway’s iconic sandwiches contained a scary-sounding chemical named azodicarbonamide.

Yoga mat: It's what's for dinner. Image by iStock.

Azodicarbonamide is used in commercial bread-making as a dough conditioner, helping to keep bread soft and spongy. It’s also used in some decidedly inedible consumer products — most famously, yoga mats.

Hari’s spark caught fire quickly. Her online petition gathered 50,000 signatures and lots of media attention. A few weeks later, a report titled "500 Ways to Eat a Yoga Mat" came out, showing the more than 400 supermarket bread products also containing azodicarbonamide. The outrage grew, and within a few weeks, Subway caved to pressure, announcing it was permanently removing the "yoga mat" chemical from its bread recipe.

Up next: getting the dog to nama-stay on his own yoga mat.

Interestingly, there is no evidence that azodicarbonamide as a food additive is harmful to human health.

A 1999 World Health Organization report on its effects found almost no effects to animals, except in massive doses. In human subjects, there’s no conclusive data, so the U.S. Food and Drug Administration allows its use as an additive in cereal flour and bread-making, along with thousands of other common products.

In the end, all the research in the world wouldn't have mattered. It really boils down to trust and transparency.

Although azodicarbonamide doesn't seem to be harmful, the public believed it was. People felt there was no way to know or agree to the chemicals being put in their food and that Subway was concealing something from them. The only option for Subway to regain consumer trust was to remove the ingredient.

Stories like this seem to happen all the time.

A consumer notices something strange about a particular ingredient in a common product. Companies assure us it's completely safe, but the public doesn't trust them and remains concerned. Eventually the pressure mounts until the company comes up with some fix to regain consumer trust. It's happened before, with "pink slime" in menu items at fast food restaurants, wood pulp in shredded cheese, and formaldehyde-releasing chemicals in makeup and cleansers.

And although those things might be technically "safe," it's clear consumers want to be a part of that decision-making process to select what goes in their food, cleaners, makeup, and other products.

This kitten doesn't know what he doesn't know — but he knows he doesn't like it.

It's clear the public wants to be more knowledgeable about what is in their products and how they are made. But currently, it can be really hard to find that information.

Ordinary people demanding transparency from the products in their lives is a fast-growing movement. To understand why and what they want, I looked to one of the most visible names of the transparency movement — the Environmental Working Group.

The Environmental Working Group, or EWG, knows firsthand how crucial consumer trust is.

Protecting children is a big driver for people in the ingredient transparency movement. Image by iStock.

Started 22 years ago by founders Ken Cook and Richard Wiles, the EWG initially focused its energy on researching the impacts of pesticides on children. But after learning more about pollutants in other areas of modern life, they expanded their efforts to include food, cosmetics, household cleaners — even tap water.

The EWG maintains massive and hyper-detailed databases of products available in the United States. Their food database — containing ingredient lists for most commercially-available foods — is what allowed them to quickly turn around the 500 Ways to Eat a Yoga Mat report. Their world-famous cosmetics database Skin Deep, is so influential that, according to the EWG Deputy Director of Research Nneka Leiba, companies have begun to reformulate their products in order to omit potentially-dangerous ingredients and get higher ratings.

Leiba explains the ingredient transparency movement using body lotion as a symbol of the deep trust consumers place in companies.

"Our relationship with our body lotions is extremely personal. We bring it into our homes, use it twice a day. Over time, it becomes an extension of our personal identity. Our trust in the safety of this lotion is extended to the company that makes it. They can choose to strengthen that with honesty and transparency. Or they can break it by doing the opposite."

In the last five years, massive corporations, including Mars, Kraft, Kellogg's, and Campbell Soup, have voluntarily opened up about the ingredients in their products and removed ones considered unsafe.

When S.C. Johnson & Son Chairman and CEO Fisk Johnson announced his company would disclose everything in their fragrances — an ingredient category protected by government regulation as "trade secrets" — he promised complete openness: "Transparency doesn't mean cherry-picking which things to share and which things to hide. It means opening the door and letting people see what you’re made of."

There are, of course, plenty of financial incentives for companies embracing ingredient transparency.

The market for natural products is continuing to expand every year. Companies selling products with very few ingredients are channeling consumer distrust into constructive purchases they feel good about and feel safe about bringing into their home. It's a growing world of products — encompassing everything from organic food to natural cosmetics to household cleaners to clothes — that's likely to get even bigger as millennials start having families and flex even more of their buying muscle.

The much sought-after millennial consumer in its natural habitat. Image by iStock.

"Consumers are demanding change, voting with their wallets and saying they won’t buy products with ingredients they don't trust," said Leiba. "So large companies like Revlon, Johnson & Johnson, and Proctor & Gamble are removing phthalates, parabens, and formaldehyde-releasing additives from their products — and then advertising it as a point of pride."

Ultimately, the ingredient transparency movement is about trust — and consumers only have a finite amount of it.

The more companies treat the people who buy their products with respect, honesty, and inclusiveness, the more likely consumers are to take them at their word.