Lactose Intolerance

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Specialists at Houston Methodist Lynda K. and David M. Underwood Center for Digestive Disorders pinpoint the cause of your digestive issues and provide a long-term nutritional plan and support to improve the quality of your daily life.


Gastroenterologists at the Underwood Center understand the concerns and disruption to the quality of life that a food intolerance brings. Lactose intolerance, or lactase deficiency, is your body´s inability to digest the milk sugar (called lactose) found in dairy products. Lactase, made up of sugars like glucose and galactose, is an enzyme produced by the lining of the small intestine.


If you do not have enough of the lactase enzyme to break apart sugars, this can lead to uncomfortable symptoms such as gas, bloating or diarrhea. Although certain symptoms are similar, this is not the same as a milk allergy, in which the body has an immune response to a protein in the milk.


Decades of patients trust the gut specialists at the Underwood Center to restore their GI health. Houston Methodist Hospital is ranked No. 5 in the nation by U.S. News & World Report for Gastroenterology & GI Surgery. U.S. News & World Report has also named Houston Methodist Hospital the No. 1 hospital in Texas every year since the award began and one of the nation’s best as a nationally ranked Honor Roll hospital.

Trusted, Supportive Digestive Care for All

 Gastroenterologists at the Underwood Center have the extensive knowledge and experience needed to accurately diagnose and treat every type and severity of lactose intolerance.


There are three types of lactose intolerance:

  • Primary lactose intolerance – develops in early childhood when milk is the primary source of calcium.
  • Secondary lactose intolerance – develops after illness, surgery or injury to your small intestine. The small intestine decreases the amount of lactase developed. Secondary intolerance may be temporary and, in some cases, reversible.
  • Congenital lactose intolerance – a rare, inherited disorder in which an infant cannot break down the lactose in breast milk or formula.


To address the challenges lactose intolerance presents, our specialists create personalized nutrition plans to reduce symptoms and restore your digestive health. 

Lactose Intolerance Symptoms, Diagnosis & Treatment

What are symptoms of lactose intolerance?

Lactose intolerance may result in any of the following GI symptoms:

  • Bloating
  • Gurgling (rumbling) sounds in the stomach
  • Loose stools or diarrhea
  • Pain or cramping
  • Passing gas
  • Vomiting

How is lactose intolerance diagnosed?

Your doctor may ask you to follow a lactose elimination diet to determine if symptoms improve when you stop eating foods containing lactose. Tests we use to check for lactose intolerance include the following:

  • Hydrogen breath test – the most common test, in which you drink a liquid solution with lactose and breathe into a balloon-like instrument to measure the level of hydrogen (higher levels of hydrogen can indicate a lactose intolerance)
  • Lactose tolerance test – blood test to measure how much glucose is in the blood (glucose levels rise when the body digests lactose)
  • Stool acidity test – stool sample to see how well the digestive system breaks down lactose (usually performed on infants or small children)

How is lactose intolerance treated?

Treatment options for lactose intolerance will differ depending on the severity of your condition. For most people, limiting the amount of lactose in their diet reduces the symptoms. Our gastroenterologists will tailor dietary recommendations to your specific needs.


If you consume dairy, try to do the following:

  • Eat dairy products in combination with other foods
  • Eat dairy products throughout the day, instead of all at once
  • Select products that have less lactose in them (such as lactose-free products)


When changing your diet routine, be mindful of the types of foods that may contain lactose. If you have severe lactase deficiency, there are several foods you might want to avoid whenever possible, such as:

  • Breads
  • Baked goods
  • Cereals
  • Cookies
  • Curds
  • Dry milk solids
  • Margarine
  • Milk chocolate
  • Milk by-products
  • Nonfat dry milk powder
  • Pancakes
  • Potatoes
  • Shakes (breakfast drinks)
  • Soups (milk or cream-based)
  • Salad dressings
  • Sweets (especially chocolate candies)
  • Whey

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