Why Does the Human Body Not Digest Corn?

It probably happened when you were just a kid — the first time you noticed that corn looks remarkably similar passing out of your body as it did going in. Although it appears that corn passes through your gastrointestinal system undigested, your body does absorb the internal nutrients.

While it might not seem like your body digests corn, it's only the outer shell that stays intact as the nutrients are absorbed by your body.
Credit: Eugene Mymrin/Moment/GettyImages

The fibrous outer shells of corn kernels, however, do not break down due to lack of the necessary digestive enzymes.

Tip

While it might not seem that your body digests corn, it is only the outer shell that stays intact as the nutrients are absorbed by your body. Corn provides dietary fiber, which helps to regulate digestion by softening the stool and promoting regularity of bowel movements.

Read more: 9 Delicious Ways to Enjoy End-of-Summer Corn

Consider Corn Anatomy

Corn kernels are the seeds of the plant. The tough outer covering of the kernel is called the pericarp, or bran coat. This portion of the kernel remains largely intact in your digestive tract. Inside the bran coat are the germ and the endosperm.

The germ is the would-be plant portion at the base of the kernel. The endosperm, which makes up the majority of the kernel, provides nourishment to the germ.

Corn is a classified as a starchy vegetable, with 98 to 99 percent of the corn's starch located in the endosperm, according to an article published in the February 2016 issue of the journal Comprehensive Reviews in Food Science and Food Safety.

Identify Digestible Nutrients in Corn

Corn contains protein, sugar, starch and fat, all of which are digested in your gastrointestinal tract and absorbed into your bloodstream. According to the USDA, 1 cup of cooked frozen corn provides you with the following:

  • 159 calories
  • 5.1 grams of protein
  • 2 grams of fat
  • 36.5 grams of carbohydrates
  • 4.7 grams of sugar

The plant fiber cellulose is the primary constituent of the bran coat of corn kernels. Like starch, cellulose consists of individual sugar molecules chemically linked together. But the way in which sugar molecules in starch and cellulose bind together differs.

Your digestive system produces enzymes that quickly and easily break down the chemical bonds in starch, releasing sugar molecules that pass into your bloodstream.

These digestive enzymes, however, cannot break the chemical bonds between the sugar molecules in cellulose, according to Elmhurst College. Therefore, the bran coat of the corn kernels passes through your intestines intact.

Read more: 9 Benefits of Corn That Earn It a Place in Your Diet

Reap the Benefits

Although corn's bran coat passes through your gastrointestinal tract without breaking down, this dietary fiber provides important health-related benefits. The cellulose in corn bran absorbs water, which keeps your stool soft and promotes regular bowel movements, according to the Mayo Clinic.

In addition, the bulkiness of water-soaked cellulose causes you to feel full for an extended period of time, which may help with weight control. According to the National Academies of Sciences, the recommended daily intake of fiber is 38 grams for males and 25 grams for females. According to the USDA, 1 cup of corn provides 3.7 grams of dietary fiber.

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