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Lactose Intolerance and Stools

author image Diane Marks
Diane Marks started her writing career in 2010 and has been in health care administration for more than 30 years. She holds a registered nurse license from Citizens General Hospital School of Nursing, a Bachelor of Arts in health care education from California University of Pennsylvania and a Master of Science in health administration from the University of Pittsburgh.
Lactose Intolerance and Stools
Because of lactose intolerance, some diets lack the nutrition benefits provided by dairy products. Photo Credit: Laboko/iStock/Getty Images

The primary symptoms of lactose intolerance include explosive and sudden bowel movements with loose and watery stools. Lactose-intolerance produces uncomfortable and embarrassing symptoms, but they do not cause any permanent damage to your digestive system. This condition results from your body's inability to digest lactose, a sugar found in dairy products. You can manage lactose intolerance through medication and diet modification. If you have a problem with your stools after eating dairy products, your doctor can determine if the problem stems from lactose intolerance or a gastric condition with similar symptoms.

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Lactose Intolerance Explained

Two simple sugars -- glucose and galactose -- combine to form lactose, a large sugar molecule too large for absorption through your small intestine. During the digestive process, the lactase enzyme breaks lactose down into glucose and galactose to make it easier for your body to digest them. If you lack the lactase enzyme, or produce an insufficient amount of lactase, bacteria in your large intestine cause undigested lactose to ferment and produce the symptoms and problems associated with lactose intolerance.

What Causes Lactose Intolerance?

The causes of lactose intolerance vary. At birth, your digestive system creates a lot of lactase to digest breast milk or infant formula. As you age, lactase production slows, which may decrease the amount of lactose you can absorb. Other causes of lactose intolerance include digestive disease, such as Crohn’s or other gastric illnesses, the stomach flu and injury to the intestines. Lactose intolerance can affect premature babies until around their expected due date.

Why Lactose Intolerance Affects Your Stool

Lactose intolerance significantly affects your stool. You may notice watery, loose, foul-smelling stool that might contain mucus. This happens when undigested lactose interacts with bacteria in the colon causing abdominal cramping, bloating, gas, diarrhea and nausea. Once bacteria interact with the lactose, the body attempts to rid itself of the undigested sugar as fast as possible, which causes the sudden urge to have a bowel movement. Most symptoms related to your stool subside after one or two bowel movements.

Treating Lactose Intolerance

Once you have ingested lactose, you cannot treat your symptoms, including your stool. Treatment includes purchasing lactose-free dairy products, lactase enzyme supplements or eliminating cow's milk from your diet. Lactose-free dairy products add lactase to the milk during the manufacturing process to eliminate lactose. A lactase enzyme taken as directed prevents most digestive symptoms associated with lactose intolerance. People with mild lactose intolerance can tolerate a small amount of lactose and do not need to avoid it altogether.

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