Sudden Lactose Intolerance: What You Should Know

If you've been experiencing uncomfortable gastrointestinal symptoms that seem to have just popped up, you might wonder if it's possible to suddenly become lactose intolerant. The answer is yes. You can indeed develop lactose intolerance as you age, and it can be temporary or permanent.

​Read more:​ Lactic Acid & Lactose Intolerance

There are four types of lactose intolerance and, according to Mayo Clinic and the National Library of Medicine, here's how these causes of lactase deficiency shake out:

• ​Primary​. This type is inherited and starts young, but some people do not recognize it until they are adults.
• ​Congenital​. Also genetic, this type of lactose intolerance occurs when both parents have a genetic mutation.
• ​Developmental​. Developmental lactose intolerance is typically a temporary condition often found in premature babies whose small intestines are not well developed.
• ​Secondary​. This type can occur at any age and can be temporary or permanent.
  

People who have low activity in lactase enzyme, which breaks down lactose, can experience sudden lactose intolerance. That is, you could become less tolerant in the event that your body experiences large intestinal changes, explains Dennis Savaiano, PhD, a nutrition professor at Purdue University, West Lafayette, Indiana.

Those changes, according to Mayo Clinic, produce secondary lactose intolerance, which occurs when the small intestine's production of lactase decreases. Malnutrition, the flu, traveler's diarrhea, surgery on the small intestine, an illness or an injury can bring it on.

Diseases associated with this kind of lactose intolerance include Crohn's disease, celiac disease and bacterial overgrowth. In those cases, treating the underlying issue may bring lactase levels back up and alleviate symptoms.

"Lactose intolerance is typically more gradual and not sudden," says Matthew Ciorba, MD, a gastroenterologist and professor at Washington University School of Medicine in St. Louis. "People may have sudden symptoms when they take in a larger amount of milk sugars and have a lot of symptoms after they previously [have] not taken in much milk product."

Telltale lactose intolerance symptoms include diarrhea, cramping, bloating, gas and sometimes vomiting, the Mayo Clinic reports.

Though there's no cure for lactose intolerance, reducing your intake of lactose-containing foods can help ease symptoms, according to the National Institute of Diabetes and Digestive and Kidney Diseases. Also, lactase products can be taken when consuming anything dairy, which can help your body digest lactose and relieve symptoms. Some people experience no symptoms if they consume only small amounts of foods that contain lactose.

If you suspect you might have become lactose intolerance, have small doses of milk with a meal to see how well your body accepts dairy and if you can build a tolerance in your microbiome. Yogurt and hard cheeses tend to be well-tolerated, Dr. Savaiano adds.

People can often determine if they are lactose intolerant without tests, Dr. Ciorba says. If you have recurrent symptoms after drinking milk products, and those symptoms don't happen when you don't have milk-containing products, it's most likely that you have a lactose deficiency or are lactose intolerant.

If symptoms persist, talk to your primary care physician or a gastroenterologist. A doctor can determine if your symptoms mean you'll be dealing with lactose intolerance as a long-term issue, if it's only temporary or if something else is causing your symptoms.

A lactose intolerance test would be a key part of the diagnosis. For one type of test, you would consume a drink that includes lactose and then have your blood drawn. If your blood glucose level does not rise as a result of the drink, that shows your body is not properly digesting and absorbing the lactose.

Another test, called the hydrogen breath test, involves drinking a beverage containing lactose and then having your breath measured for the amount of hydrogen in it. When your body doesn't digest correctly, the colon releases hydrogen and other gases. Gauging how much hydrogen you have in your breath can indicate if you are lactose intolerant.

​Read more:​ Decoding Your Gut: The Ultimate Guide to the Microbiome, Digestive Issues and More