It's Common For People to Become Lactose Intolerant Upon Adulthood — Here's Why

Cheese is my one true (food) love — I plan on enjoying all the Brie, Gouda, and Manchego I can get because our future together isn't always promised.

According to Dr. Morgan Sendizchew Shane, MD, a gastroenterologist from the University of Miami Health System, lactose intolerance is normal with aging because, in some cases, the body stops making copies of the gene that makes the enzyme (lactase), which digests lactose, the main carbohydrate in dairy products.

"The degree of lactose intolerance, meaning how sensitive you are to dairy products, can vary from person to person because different people can have different levels of the digestive enzyme lactase, which digests the lactose."

When someone is lactase deficient, lactose passing through their digestive system ends up in the colon instead of being absorbed as nutrients in the small intestine, Dr. Brooke Goldner, MD, a board-certified physician that specializes in nutrition and gut health, says. Once in the colon, the lactose is left to be broken down by bacteria, which can cause symptoms such as bloating, flatulence, stomach cramps, and diarrhea, she adds.

Dr. Goldner says that most infants have the lactase enzyme because they rely on milk for nutrition. Once a human's diet doesn't require milk because of the ability to eat solid foods, one can develop a decrease in lactase production by adulthood — this is called primary lactose intolerance.

There is such a thing as secondary lactose intolerance, too, which can arise with inflammation of the colon or after surgeries, but sometimes this condition can improve as the bowls heal, she explains.

According to Mayo Clinic, it's possible (but very rare!) for babies to be born with lactose intolerance that's been passed down from generations — but both the mother and the father must pass on the same gene variant for a child to be affected. This is called congenital or developmental lactose intolerance.

The good news is that lactose intolerance symptoms usually improve within one to two weeks of starting a lactose-free diet, Dr. Shane says. But even if you're feeling better, you should always talk to your doctor if experiencing a new onset of gastrointestinal distress.

"Never hesitate to seek care from your doctor if you have any questions about how your diet may be affecting your health," Dr. Shane adds.

If you think you have tried to limit or eliminate the dairy in your diet and you are still having symptoms, it is worth a visit to your doctor."

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