By Julie Garden Robinson, Food and Nutrition Specialist

NDSU Extension Service

“How long do you think your small intestine is?” my student dietetic interns asked the third- grade class we were visiting.

As we taught the class about digestion, we used rubber tubing to represent the length of a small intestine. One of the third-graders eagerly came to the front of the room to pull a length of rubber tubing out of a bag until we reached the length of the small intestine.

The class helped the student decide when to stop. The student stopped after he pulled out 5 feet of tubing, but we said the small intestine was longer. Soon the student was dragging the length of tubing around some desks and halfway across the classroom.

We were out of tubing. The average length of our small intestine is 20 to 25 feet.

The third-graders seemed impressed.

“How does all that fit inside us?” one of them asked.

My students explained that intestines are folded and we all have this long, narrow tube to allow us to absorb nutrients from food and beverages for use by our body.

After several activities, we could tell that the children had “digested” the lesson material quite well. They told us they would be teaching their parents about nutrition at home.

Are you smarter than a third-grader? Try these questions, which we asked the students after the digestion lesson. Some questions are harder than others.

1. What substance in our mouth helps mix and start the breakdown of food?
2. What action in the mouth helps break apart your food?
3. How many muscles are in the esophagus?
4. Two-part question: What part of the digestive system mixes up your food? After your food is mixed, what is the resulting mixture called?
5. How many liters of food and liquid can a stomach hold when full?
6. How long is your large intestine?
7. What five food groups make up MyPlate?
8. Which food groups are good sources of fiber?

How did you do? Here are the answers.

1. Saliva in our mouth begins the digestion process by lubricating food, which helps with chewing and swallowing. Saliva contains an enzyme (amylase) that begins the breakdown of starches into sugars. That is why a cracker tastes sweeter after we chew for a while.
2. Chewing breaks apart foods. Along with providing us a dazzling smile, strong teeth allow us to chew our food properly, which aids our ability to digest our food properly. Don’t forget to brush and floss your teeth.
3. The esophagus consists of two layers of muscles. We can swallow even if we eat upside down. However, we don’t recommend eating in that position because you could choke.
4. Your stomach is a muscular organ that mixes your food. The resulting mixture is called chyme (pronounced like “rhyme” with a “k”).
5. On average, a stomach can hold about a liter (about 4 cups) of food and liquid. That’s why you might feel uncomfortable after eating a lot of food.
6. Your large intestine is about 5 feet long. Twice as wide as the small intestine, the large intestine is where water is reabsorbed prior to the waste leaving your body.
7. The latest nutrition icon, MyPlate, is made up of these food groups: fruit, vegetable, grain, dairy and protein foods. You can learn more at http://www.choosemyplate.gov.
8. Fruits, vegetables, whole grains, dry edible beans and pulses are good fiber sources. Most of us do not meet the 25- to 30-gram daily recommendation.

To help meet your fiber needs, fill half your plate with fruits and vegetables, make half your grain choices whole grains, and add some dry edible beans and pulses, such as chickpeas, lentils and split peas, to your menu. When adding fiber, start slowly and drink plenty of water.

For good digestive health, you also need plenty of physical activity such as walking. Here’s a fiber-rich snack we provided for the children to taste test with whole-grain crackers. The kids pronounced this dip “awesome.”

Seven-layer Dip

1 (16-ounce) can refried beans

1 (1-ounce) package taco seasoning mix

1 (8-ounce) package cream cheese, softened

1 (4.5-ounce) can chopped green chilies

1 c. thick and chunky salsa

2 c. shredded lettuce

2 c. shredded cheddar or Mexican cheese blend (8-ounce)

1 medium tomato, finely diced (3/4 c.)

Baked tortilla chips or whole-wheat crackers

In medium bowl, mix refried beans and taco seasoning mix. Spread mixture on large platter. In another medium bowl, mix cream cheese and chilies. Carefully spread over bean mixture. Top with salsa, lettuce, cheese and tomato. Refrigerate until serving time. Serve with tortilla chips or whole-wheat crackers.

Makes 16 servings. Each serving has 130 calories, 7 grams (g) of fat, 7 g of protein, 10 g of carbohydrate and 550 milligrams of sodium

(Julie Garden-Robinson, Ph.D., R.D., L.R.D., is a North Dakota State University Extension Service food and nutrition specialist and associate professor in the Department of Health, Nutrition and Exercise Sciences.)

NDSU Agriculture Communication – March 1, 2012