Is that carb ultra-processed? Try this easy water test : NPR

For the first time, the US government is urging people to avoid “highly processed” foods, which it says cause diet-related illnesses. But this recommendation puts many Americans in a difficult situation. Studies show that many people to want to reduce the amount of ultra-processed foods in their diet, but they have difficulty determining which foods fall into this category.

“I think advertising is really effective at making people believe that foods are minimally processed when they’re actually ultra-processed,” says Alexandra DiFeliceantonio, who studies the neuroscience of food selection at Virginia Tech.

Ultra-processed foods are industrially manufactured products that contain ingredients rarely found in your kitchen, such as preservatives, artificial sweeteners, colors, natural flavors and emulsifiers. Many studies have shown that these foods increase the risk of many health problems, including diabetes, heart disease, depression and obesity.

“When people ask me about ultra-processed foods, they’re often confused about grains, carbs, and starches,” says Dr. Dariush Mozaffarian, who directs the Food is Medicine Institute at Tufts University. These foods include bread, crackers, pretzels, split peas, veggie straws, pasta, and rice or popcorn. “People want to know how to choose healthier versions of these products,” he says.

So Mozaffarian gives his patients two handy rules of thumb to follow when selecting grains and starches: the 10-to-1 test and the water test.

1. The 10 to 1 test

“A food should contain at least one gram of fiber for every 10 grams of carbohydrates,” says Mozaffarian. For example, if you’re considering purchasing a granola bar, look at the nutrient label. If the bar contains 30 grams of total carbohydrates, it should also contain at least three grams of fiber. Otherwise, choose another bar.

This test, he says, ensures that foods don’t just contain refined flours and sugars. “So there’s a balance between refined starches, whole grains, bran, seeds and other healthy ingredients.,” Mozaffarian explains.

And he says food must also pass “the water test.”

2. The water test

Simply take the starchy foods – for example a piece of bread, a cracker, a pretzel or cereal – and put them in a glass of water. Let it sit in the water for three or four hours and see what happens.

The author’s daughter tests the water for starchy foods by soaking pieces of bread in a glass of water for a few hours.

Michaeleen Doucleff

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Michaeleen Doucleff

Look specifically to see if the grain or starch dissolves or disintegrates in water, he says.

Minimally processed grains, such as whole wheat bread and steel-cut oats, have the plant’s cell wall still intact, which surrounds the carbohydrate chains and forms a sort of shield or barrier around them. The plant cell wall prevents carbohydrates from dissolving in water.

So if the carbohydrates doesn’t dissolve in water, it’s probably a minimally processed food, Mozaffarian says. And it’s a healthy choice because, he says, the cell wall does something else important: It makes grains difficult to digest.

After you eat a carbohydrate, enzymes in your mouth and stomach break down the starch into simple sugars, which then enter your bloodstream. In a way, Mozaffarian says, the water test models the process in your digestive tract.

Your enzymes cannot act on carbohydrates when they are protected by the cell wall. So you digest minimally processed grains much more slowly than ultra-processed grains. This slow digestion is good for you, says Mozaffarain. “It doesn’t overwhelm your liver or the hormones responsible for metabolism.” And in the long term, it reduces your risk of weight gain and diabetes.

This slow digestion also means that carbohydrates travel further into your gut, where they can feed the microbes in your large intestine, called the microbiome. You need a healthy microbiome to thrive.

On the other hand, ultra-processed grains and starches don’t get very far into your gut because of the way they’re made, says Dr. Meroë B. Morse, an assistant professor at MD Anderson Cancer Center. Companies, in fact, predigest cereals, corn or potatoes, and in doing so, they remove the cell wall of the plant. “The grain or starch is ground down to its individual ingredients, then repackaged and glued together,” she explains.

This causes enzymes in your gut to quickly break down carbohydrates into simple sugars.

“These foods digest very quickly in the stomach and can create a glucose spike,” Morse says. “And when you have a blood sugar spike, insulin levels tend to increase.” Over time, these spikes can contribute to insulin resistance and eventually diabetes, she says.

So when choosing grains, starches, and other carbs, you want ones that will hold together in both your gut and a glass of water.

This is where water testing comes in.

The results of water testing with homemade bread (right) and commercially processed bread (left).

Michaeleen Doucleff

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Michaeleen Doucleff

A simple experience

A few weeks ago, my 10-year-old daughter and I made a loaf of whole wheat bread in our kitchen. And we decided to give it the water test.

For comparison, we bought a French baguette at the grocery store, which contained preservatives, dextrose, wheat gluten, as well as a “dough conditioner” and a “crumb softener.”

We took a piece of both loaves, put them in two glasses of water and waited for about three hours. Then we looked at each piece.

The homemade whole wheat bread had absorbed some water, but it remained intact and there was no sign of the starch dissolving in the water. The water remained clear. Ding, ding, ding! Our homemade whole wheat bread passed the water test with flying colors.

But the French baguette had been remarkably transformed. “Oh, wow!” my daughter exclaimed as she took the bread out of the glass of water. “It’s like a sponge, or slime, or Play-Doh!”

The wand had absorbed a huge amount of water and had almost turned into a kitchen sponge that could be squeezed out and reused. Additionally, the water in the cup was cloudy and white because the starch had begun to dissolve in it.

Bzzzt! The wand failed the water test. This result confirms that this bread is ultra-processed.

But the water test had a different effect on my daughter. This helped her understand – and see for herself – how ultra-processed breads may look like homemade breads, but they act very differently in our bodies.

“It’s a little disgusting,” she said, squeezing the piece of ultra-processed bread like a sponge. “Bread shouldn’t be like that.”