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11.20: Health of the Digestive System

Difficulty Level: At Grade Created by: CK-12
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Have you ever been sick to your stomach?

You may have even had to stay home from school because of a "stomach bug." It is possible that you caught a contagious illness, or you could have gotten sick from food you had eaten recently. The symptoms are very similar, so it's hard to pinpoint the cause.

Health of the Digestive System

Most of the time, you probably aren’t aware of your digestive system. It works well without causing any problems. But most people have problems with their digestive system at least once in a while. Did you ever eat something that didn’t “agree” with you? Maybe you had a stomachache or felt sick to your stomach? Maybe you had diarrhea? These could be symptoms of foodborne illness, food allergies, or a food intolerance.

Foodborne Illness

Harmful bacteria can enter your digestive system in food and make you sick. This is called foodborne illness. The bacteria, or the toxins they produce, may cause vomiting or cramping, in addition to the symptoms mentioned above. You can help prevent foodborne illness by following a few simple rules.

  • Keep hot foods hot and cold foods cold. This helps prevent any bacteria in the foods from multiplying.
  • Wash your hands before you prepare or eat food. This helps prevent bacteria on your hands from getting on the food.
  • Wash your hands after you touch raw foods, such as meats, poultry, fish, or eggs. These foods often contain bacteria that your hands could transfer to your mouth.
  • Cook meats, poultry, fish, and eggs thoroughly before eating them. The heat of cooking kills any bacteria the foods may contain, so they cannot make you sick.

Food Allergies

Food allergies are like other allergies. They occur when the immune system reacts to harmless substances as though they were harmful. Almost ten percent of children have food allergies. Some of the foods most likely to cause allergies are shown below (Figure below).

Eating foods you are allergic to may cause vomiting, diarrhea, or skin rashes. Some people are very allergic to certain foods. Eating even tiny amounts of the foods causes them to have serious symptoms, such as difficulty breathing. If they eat the foods by accident, they may need emergency medical treatment.

Some of the foods that commonly cause allergies are shown here. They include nuts, eggs, grains, milk, and shellfish. Are you allergic to any of these foods?

Food Intolerance

A food intolerance, or food sensitivity, is different from a food allergy. A food intolerance happens when the digestive system is unable to break down a certain type of food. This can result in stomach cramping, diarrhea, tiredness, and weight loss. Food intolerances are often mistakenly called allergies. Lactose intolerance is a food intolerance. A person who is lactose intolerant does not make enough lactase, the enzyme that breaks down the milk sugar, lactose. Lactose intolerance may be as high as 75% in some populations, but overall the percentage of affected individuals is much less. Still, well over 10% of the world's population is lactose intolerant.


  • food allergy: Overreaction of the immune system to harmless foods.
  • food intolerance: Inability of the digestive system to handle certain types of food.
  • foodborne illness: Illness resulting from eating contaminated food.


  • Foodborne illness can be prevented by taking precautions during food preparation.
  • Food allergies and food intolerance can upset your digestive system.


Use the resources below to answer the questions that follow.

  1. What is a food allergy? How does the body respond to food allergies?
  2. What does the phrase "dose related" mean? How does this relate to food intolerance?
  3. What are four common symptoms of food allergies?
  4. What are the most common food allergens?
  5. Do all people of all ages respond in the same way to foods?
  1. What is the most basic step to preventing foodborne illness?
  2. Why is it a good idea to use one cutting board for fruits and vegetables and another for meats?
  3. What can happen if you leave food sitting out exposed?


  1. List two rules that can help prevent foodborne illness.
  2. What's the difference between a food allergy and a food intolerance?

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food allergy Overreaction of the immune system to harmless foods.
food intolerance Inability of the digestive system to handle certain types of food.
foodborne illness Illness resulting from eating contaminated food.

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Difficulty Level:
At Grade
7 , 8
Date Created:
Nov 29, 2012
Last Modified:
Aug 30, 2016
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