Corn has a way of staying intact from pot to poop. The bright yellow grains found in our favorite summer dishes can appear – seemingly undigested – in the bathroom hours later. How does corn survive the digestive system? And perhaps more importantly, should you also eat a hard-to-digest food?
It turns out that your digestive system is doing more work than you think, so don’t skip the corn just yet. The yellow kernels in your poop are actually just the outer coating of the corn kernel, according to Andrea Watson, a ruminant nutritionist at the University of Nebraska-Lincoln.
Corn kernels are seeds that carry valuable genetic material. The key to seed survival is the waxy, yellow outer coat that protects the genetic material from weathering, parasites and transport. The fact that it is difficult to break down is actually ideal for the plant. The outer coating owes its strength to a hard one fiber called cellulose, which humans don’t have the proper enzymes or gut bacteria to digest.
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Even ruminant animals, such as cattle, which are much better equipped to digest cellulose, cannot always fully digest corn, Watson told Live Science. While cattle don’t eat the same soft, sweet corn that we do (they eat harder, more mature corn that can be stored for the long term), they too have whole grains that show up in their manure. The researchers did the dirty work of identifying the expelled grains and analyzing their nutritional content. “It turns out [the kernels] they’ve been digested quite a bit, “Watson said.
The good news is that cellulose makes up only about 10 percent of corn, Watson said. So, the other 90% is useful nutrition. Corn is also a good source of dietary fiber, starch and antioxidants known as carotenoids, which give vegetables like corn and carrots their gorgeous colors. However, there are fewer carotenoids in corn than in a typical serving of green leafy vegetables, according to a Tufts University Report 2019.
There is a way to make corn more digestible and completely disappear from your poop: processing. “The more you process it, the easier it is to digest,” Watson said. This is true for both humans and animals. Grinding, wet grinding, cooking – each processing step further breaks down those hard-to-digest fiber molecules, he said.
In fact, most of the corn you eat is processed. The Tufts University report estimates that each American consumes 160 pounds. (70 kilograms) of corn per year. The vast majority of that corn is not the hard-to-digest grain that has been gnawed off the cob, but the corn has been made into soft tortillas, chips, popcorn and – the big one – high fructose corn syrup.
Easier to digest, however, shouldn’t be confused with healthier. A look at the nutrition facts shows common processed corn products, such as corn oil is high fructose corn syrup, it loses most of the fiber and beneficial nutrients during processing. The corn kernels in your poop might be weird, but they’re not bad for your health. In fact, it is a sign that you are eating corn in one of its healthiest forms. Watson’s best advice to avoid seeing whole grains in the bathroom: chew carefully.
Originally published in Live Science.