Lactose Intolerance: Spotting the Signs & Preventing Symptoms

It's summer vacation, which means your air conditioner is working overtime and so are the ice cream trucks.

While the promise of a cold, sweet treat is enticing, consider how your stomach may feel after you're done with your cone. About 68% of the global population is lactose intolerant, according to the National Institutes of Health.

Before you order your next ice cream sundae, learn about the signs of lactose intolerance to see if dairy is the smart choice for your stomach.

How does lactose intolerance work?

"Lactose, which is a type of sugar molecule, is broken down in the gut by an enzyme called lactase," explains Dr. Phillip Simpson, a family medicine and primary care physician at Houston Methodist. "After infancy, when we're no longer dependent on milk as our main source of nutrition, we often don't produce as much lactase."

Low levels of lactase mean that the body cannot effectively break down lactose into glucose and galactose. This undigested lactose ferments in the colon, causing gas, bloating, and other symptoms.

Most of these symptoms develop about 30 minutes to two hours after consuming products containing lactose.

Is this different from an allergy?

Lactose intolerance is not the same as an allergy.

"Allergies are a type of immune response," Simpson explains. "Undigested lactose causes symptoms due to a lack of processing, but it is not an allergic reaction. Milk allergies are specifically a reaction to milk protein, not the lactose sugar."

Milk allergies are a real but separate condition that can vary in severity and manifests like other common food allergies. Symptoms may include hives, swelling of the lips, tongue or throat, vomiting and even anaphylaxis.

What can I do to relieve my symptoms?

"After a while, your symptoms will go away on their own," Simpson says.

The best way to avoid further discomfort is to avoid more lactose intake. There is not yet a way to make the body produce more lactase, so removing lactose from the diet is the best solution.

While there's no treatment to reverse the condition, you can try taking a lactase enzyme supplement right before consuming products with lactose.

This supplement may prevent you from experiencing more unpleasant symptoms after dairy consumption.

How can I test for lactose intolerance?

There are many different confirmatory tests that you can take to test for lactose intolerance.

Simpson suggests the hydrogen breath test and the lactose tolerance tests for more definitive diagnoses. Both of these tests are performed before and after consuming a lactose-rich drink.

The hydrogen breath test works because fermentation occurs when your body cannot break down lactose. Fermentation releases hydrogen, so the test shows higher hydrogen levels after the drink than before. The lactose tolerance test is a blood test that works by comparing your blood sugar content before and after the drink containing lactose.

If these tests are not practical for you, Simpson recommends a lactose-free trial period for one to two weeks.

What are the different types of lactose intolerance?

There are three main types of lactose intolerance: primary, secondary and congenital.

Primary lactose intolerance

Primary intolerance is a genetic predisposition involving the body's reduction in lactase production after infancy. This is accompanied by a gradual, natural decrease in the ability to tolerate lactose.

"It is natural for one's lactase production to decline over time," Simpson says. "Everyone's timeline is different. Perhaps people are born less tolerant because some populations historically relied on dairy more than others."

Secondary lactose intolerance

Secondary intolerance is typically caused by intestinal diseases or other inflammatory conditions that wipe out the lactase, and the cells that produce more of it.

Crohn's disease or celiac disease are two examples of this type of intolerance.

Congenital lactase deficiency

This deficiency is the rarest type of lactose intolerance and requires immediate treatment.

"This is an inherited condition where a baby is born unable to produce lactase," Simpson says. "Dietary intervention is needed right away to avoid serious complications for the baby such as dehydration and weight loss."

What unsuspecting items should I avoid?

Lactose and dairy products are commonly used as additives or fillers.

Certain processed foods — such as some breads, salad dressings, lunch meats, and protein powders — may contain small amounts of lactose, especially if dairy is used as a filler or binder. While these usually don't cause symptoms in most people with lactose intolerance, highly sensitive individuals may want to check labels.

Solid oral medicines, such as tablets and capsules, are the most common medicines that contain lactose. You can check the label for variations of "lactose" in the inactive ingredient list or consult with the pharmacist if you are worried about experiencing uncomfortable symptoms or prefer a different medication. Dr. Simpson notes that these amounts too are very small and rarely cause issues unless the patient is extremely sensitive.

Can lactose intolerance be dangerous?

"Lactose intolerance is not typically a dangerous condition, it's more of a discomfort," says Simpson.

Apart from a congenital lactase deficiency, there is generally not an immediate risk associated with lactose intolerance.

However, dairy is a good source of protein, calcium and vitamin D. If you decide to stop consuming products with lactose, be mindful of your protein and vitamin consumption to stay healthy. You may want to consider taking a lactase supplement before consuming dairy or finding lactose-free dairy alternatives.