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Diarrhea and Lactose Intolerance: When Dairy Is the Problem

Milk may do a body good, but not if you’re one of 30 to 50 million people who suffers from lactose intolerance. Lactose intolerance results from an inability to digest the natural sugar (lactose) found in milk and milk products. Lactose intolerance symptoms can include bloating, diarrhea, gas, and cramping. But there are ways to manage lactose intolerance while reaping the nutritional benefits of dairy products.

What Causes Lactose Intolerance?

Lactose is the natural sugar found in milk and dairy products. Lactase, an enzyme in the small intestine, is needed to break down the sugars for full digestion and absorption into the body. If you don’t have enough of the enzyme, you may get diarrhea and upset stomach when you eat or drink dairy products – although not everyone with a lactase deficiency has lactose intolerance symptoms. You may experience mild, moderate, or severe symptoms, depending on how much lactase your body produces. 

Most people develop low lactase levels during mid-childhood (around 5 years old). In some people, low levels continue into adulthood.

Lactase deficiency can also be caused by:

  • Genetics: Although rare, some people may be born with a gene mutation that prevents them from producing lactase. Affected babies usually have diarrhea from birth.
  • Premature birth: Premature babies may not produce enough lactase at first. In these cases, the amount of lactase produced increases with time.
  • Other health conditions: Certain diseases, such as celiac disease, inflammatory bowel syndrome, cystic fibrosis, and Crohn’s disease, as well as injuries to the small intestine, can lead to a reduction in the production of lactase. 

Lactose intolerance is less likely to affect people of northern European descent. Those most likely to experience lactose intolerance symptoms include:

  • African-Americans: They are up to 80% more likely to be lactose intolerant that others.
  • Asian-Americans: They are 90%-100% more likely to be lactose intolerant.
  • Native Americans: They are 80%-100% percent more likely to be lactose intolerant.


How Can I Control Lactose Intolerance Symptoms?

If you are lactose intolerant, you may experience mild to severe symptoms, including diarrhea, between 30 minutes to two hours after eating or drinking dairy products. Other symptoms may include nausea, bloating, stomach cramps, and gas.

You can control lactose intolerance symptoms by making changes in your diet, such as eliminating dairy products. However, you may find that you do not have to eliminate dairy entirely. For example, you may discover that some cheeses, like Swiss, cheddar, feta or goat cheeses, don’t bother you, while other ones cause symptoms. Or you may be able to have one glass of milk but not more.  

Other strategies for controlling lactose intolerance symptoms include:

  • Eating and drinking lactose-free milk and dairy products (available at most grocery stores) such as soy or rice milk and soy cheese
  • Eating a solid food with a dairy product (such as cereal with milk)
  • Taking a lactase enzyme (available as tablets or liquid over-the-counter at drug stores) when you eat dairy

WebMD Medical Reference

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