Whole Foods, one of the largest health-conscious grocery stores in America, maintains a list of “Unacceptable Ingredients for Food.” The store’s blacklist is 78 ingredients long and contains many well-known villains in the eyes of health-conscious eaters—aspartame, MSG, and high fructose corn syrup, to name a few. Though Whole Foods has grown over the years—it currently boasts more than 300 locations nationwide—it’s still a small operation in comparison to Walmart, which runs more than 3,000 food-selling supercenters in the U.S., making it the largest grocery store in the country and indeed the world. Walmart does not ban any of the ingredients on Whole Foods’ restricted list. In fact, approximately 14 percent of food items sold at Walmart could not be stocked on the shelves of Whole Foods simply because they contain high fructose corn syrup. When all 78 ingredients banned by Whole Foods are taken into account, roughly 54 percent of food items sold at a Walmart would be prohibited at Whole Foods.

Walmart posts on its website the ingredients of 19,900 food products it carries in its grocery sections. To create my data set, I matched the ingredients of each product against Whole Foods’ “Unacceptable Ingredients for Food” list. It should be noted that while 19,900 products constitutes a large sample, it does not represent the totality of Walmart’s food offerings, as there are many products for which the chain does not provide nutritional information on its website, and other products it doesn’t list at all. The Food Marketing Institute estimates that the average supermarket stocks approximately 42,000 items. When I asked a Walmart spokeswoman via email if the 42,000 figure held true for its stores, she responded that the number varies from store to store, based on format, and declined to provide an average.

Many of the ingredients banned by Whole Foods are ones that frequently show up in processed foods, products that have been prepared and packaged in a way that allows them to be sold on a mass scale at a later date. Given the popularity of processed foods among American shoppers, and the disdain for preservatives in health food circles, it’s perhaps not surprising that one out of every two products sold at Walmart has an ingredient banned by Whole Foods. Consider the soft drink category. Of the soft drinks sold at Walmart, approximately 97 percent contain ingredients that Whole Foods considers “unacceptable.” High fructose corn syrup and the preservative sodium benzoate, both on Whole Foods’ banned list, are in the majority of Walmart’s soft drinks.

If you’re trying to avoid unnatural ingredients you may not be a soda drinker. But let’s look at the seemingly more natural category of water. More than 36 percent of drinks that Walmart labels as “water” also have ingredients that disqualify them from Whole Foods’ shelves. While standard Aquafina and Aquafina FlavorSplash Lemon Water have similar packaging and might even be sold on the same shelf, the latter contains four ingredients (sucralose, calcium disodium EDTA, acesulfame potassium, and potassium sorbate) that would prohibit its sale at Whole Foods.

Water isn’t the only surprising category where Whole Foods’ banned substances show up. Even Walmart’s “Great Value 100% Whole Wheat Bread” contains seven ingredients that Whole Foods considers “unacceptable”: high fructose corn syrup, sodium stearoyl lactylate, ethoxylated diglycerides, DATEM, azodicarbonamide, ammonium chloride, and calcium propionate.

Here’s an interactive chart showing roughly how prevalent some of the most common of Whole Foods’ banned ingredients are in various Walmart products based on the sample of 19,900 products:

Of course, it’s important to remember that, while Whole Foods has attached a stigma to the ingredients it’s declared “unacceptable,” all of these ingredients are approved by the Food and Drug Administration. Whole Foods doesn’t offer much of an explanation on its website for why it has banned these ingredients. A representative from the company explained by email that the decision to prohibit an ingredient comes from “many factors including safety, necessity, manufacturing methods and compatibility with our overall core values.”

I asked Marion Nestle, professor of nutrition, food studies, and public health at New York University, what she thought about Whole Foods’ banned ingredient list and how concerned consumers should be about consuming them. Nestle said that the health effects of artificial ingredients are hard to know with complete certainty. Aspartame, for example, is an ingredient that has been the subject of much public debate. Yet almost all health bodies have concluded it is safe for consumption. “A study proving [aspartame] is safe or unsafe would take years and be hard to do,” Nestle said. “It is difficult to prove something is totally safe.”

There are some ingredients that Nestle was surprised to see on Whole Foods’ “Unacceptable Ingredients” list, including high fructose corn syrup. While high fructose corn syrup is often singled out as a cause of America’s high obesity rates, Nestle says that “biochemically it is no different than sugar.” Sugar, obviously, is not banned at Whole Foods, and you could eat an unhealthy amount of Whole Foods’ own “Chocolate Sandwich Cremes,” which contain cane sugar, as easily as an unhealthy amount of Oreos, which contain high fructose corn syrup. “One of the things that Whole Foods is responding to is customer concern,” Nestle said. “High fructose corn syrup has a bad reputation among consumers, and Whole Foods is giving their demographic what their demographic wants.”

Whole Foods has not always imposed a ban on high fructose corn syrup. According to a Whole Foods spokeswoman, it was added in 2011 after “our shoppers expressed growing concerns about its pervasive use in some products like soft drinks, baked goods, jams, jellies, breads, cereals and condiments.”

How hard would it be to shop at a Walmart and buy foods with no ingredients deemed “unacceptable” by Whole Foods? We took a look at some common Walmart aisles and analyzed which of the products are free of ingredients banned by Whole Foods. Drag the slider below across the aisles to reveal what the shelves of Walmart would look like if it screened for Whole Foods’ verboten ingredients.

Predictably, the snack aisle is full of products with artificial ingredients. But the number of items in the bread and meat aisle containing artificial ingredients may also strike readers as alarming. Meat often contains sodium diacetate, which some studies have shown to be a mild eye irritant, and monosodium glutamate (also known as MSG) which has been blamed for everything from nausea to cancer, though government food safety organizations around the world have routinely reaffirmed it as safe. The culprit in banned breads lies in high fructose corn syrup as well as the preservatives calcium peroxide and calcium propionate, which some have fingered as a cause of stomach ulcers and skin irritation.

In addition to its restrictions on ingredients, Whole Foods also bans food items based on concerns about animal welfare, genetically modified organisms, and sustainability. Walmart has no public equivalent of Whole Foods “Unacceptable Ingredients for Food,” but it does follow a set of guidelines beyond those mandated by the FDA and Department of Agriculture. The Global Food Safety Initiative was founded by major retailers in 2000 after, according to its website, it was determined that “consumer trust needed to be strengthened and maintained through a safer supply chain.”

“We require all of our suppliers to meet or exceed all government regulatory standards. There are times when we go above and beyond what is required by U.S. law,” the Walmart spokeswoman wrote via email. “For example, in 2010 we stopped selling sprouts due to the inherent microbial risks associated with them. The government didn’t ask us to stop selling them; we did this on our own.”

Generally, however, Walmart’s policy is to let the consumer decide: “We serve more than 140 million customers per week in the United States and we believe in giving our customers a wide assortment of groceries so they can decide what is the best choice for their family.” Do you prefer laissez-faire shopping (and the lower prices that come with it) or highly regulated shopping (and the peace of mind that comes with it)? The answer likely comes down to your politics—and your pocketbook. Take the quiz below to test your knowledge of which foods are acceptable by Whole Foods standards and which are not.

Correction, Feb. 20, 2014: A chart in a previous version of this article misstated what percentage of Walmart cheese products contain sucralose. It is 0 percent, not 35 percent.