Lactose intolerance is the inability to digest lactose, the sugar found in milk. It is caused by a deﬁciency of lactase, the enzyme needed to break down lactose dur- ing digestion. Symptoms of lactose intolerance include nausea, cramps, bloat- ing, gas, and diarrhea. In general, symptoms appear about a half hour to 2 hours after a person eats or drinks food that contains lactose. Not all people with lac- tase deﬁciency experience symptoms, and the severity of symptoms varies from person to person. The disorder is especially common among adults of Asian, African, and Native American descent.
If you regularly experience symptoms of lactose intolerance when you con- sume dairy products, you may be lactose intolerant. To avoid these symptoms, your doctor may recommend that you consume smaller portions of your favorite dairy foods, eat only those dairy products that contain added lactase, or take over-the-counter lactase supplements (in liquid or tablets). He or she may rec- ommend that you follow a dairy-free diet. Because not all dairy products cause symptoms in all people who are lactose intolerant, you may ﬁnd some dairy foods easy to digest, and others intolerable.
Celiac disease is an allergy to gluten, a protein contained in most grains. In people with celiac disease, gluten damages the lining of the small intestine and
interferes with its ability to absorb nutrients from food. Most cases of this rare disorder are diagnosed in infancy or early childhood. It is possible, however, for celiac disease to appear for the ﬁrst time in an adult.
Gastrointestinal symptoms of celiac disease include recurring abdominal swelling and pain; fatty, yellow stools; and gas. Weight loss and unexplained anemia (characterized by fatigue and weakness) often occur. Other possible symptoms include bone or joint pain, muscle cramps, tooth discoloration, tin- gling and numbness in the legs, mouth sores, a painful skin rash, and behavior changes (such as depression). To diagnose celiac disease, doctors perform spe- cial blood tests and use an endoscope (viewing tube) to help remove tissue sam- ples from the small intestine for microscopic examination.
Treatment for celiac disease is to follow a strict gluten-free diet. You will need to avoid wheat, rye, barley, and other grains that contain gluten. You also will need to watch for hidden gluten in foods such as pasta and beer. Rice and corn are safe to eat, and gluten-free ﬂour and other food products also are available. Symptoms will begin to improve within a few days of beginning the diet, though full recovery may take up to 2 years. If left untreated, celiac disease can lead to intestinal cancer, osteoporosis (see page 301), and seizures.
Keeping Your Digestive System Healthy
Most digestive system disorders can be prevented by following a healthy lifestyle. The following tips help you keep your digestive system healthy:
• Consume at least 20 to 25 grams of ﬁber daily.
• Exercise regularly.
• Drink at least eight glasses of water (8 ounces each) every day.
• Avoid using laxatives except under your doctor’s supervision.
• Reduce the amount of fat in your diet.
• Do not smoke or use other tobacco products.
• Use safe food handling and storage procedures.
• Avoid drinking, washing, or cooking with water that may be contaminated by microorganisms.