What Are Symptoms of Being Lactose Intolerant?

Lactose intolerance is caused by an inability of the body to absorb lactose, the naturally occurring sugar in dairy products. The small intestine produces low levels of the enzyme lactase which breaks down lactose, so people without it are unable to digest all the lactose they consume.

The causes of an inability to produce adequate lactase include:

• Certain genetic conditions
  • Lactase nonpersistence (also called primary lactase deficiency), the most common cause of low lactase levels
  • Congenital lactase deficiency, starts at birth (rare)
• Injury to the small intestine (secondary lactose intolerance)
  • Infections, diseases, or other conditions that injure the small intestine
    • Crohn’s disease 
    • Celiac disease
  • Certain treatments
    • Some medicines
    • Surgery
    • Radiation therapy
• Premature birth

Lactose intolerance is more common among Asian, Native American, and black people.

Lactose intolerance is not a food allergy, in which the body’s immune system reacts to the protein in dairy products, rather than the sugars. 

Testing to diagnose lactose intolerance includes:

• Lactose hydrogen breath test 
  • Patients drink a liquid containing lactose and then breathe into a special machine every 30 minutes
  • The machine measures the amount of hydrogen that is exhaled
  • People with lactose intolerance breathe out more hydrogen than normal
• Lactose tolerance test 
  • Patients drink a liquid with lactose in it
  • Blood samples are taken when the test starts, and again 1 and 2 hours later
  • If the blood has low levels of sugar after drinking the lactose, it usually indicates lactose intolerance

Treatment for lactose intolerance includes: 

• Limiting or avoiding dairy products
• Taking an enzyme supplement to help break down the lactose in dairy foods
  • Lactaid (tablets or liquid), Lactrase, LactAce, Dairy Ease, and Lactrol
  • Take enzyme supplements right before eating
  • Enzyme supplements may be taken during a meal, but it might not work as well
  • These products can’t always break down all the lactose so symptoms may still occur even if the supplement is used
  • Talk to your doctor before using enzyme supplements, as they may not be recommended for some people, such as children and pregnant or breastfeeding women
• Supplementing nutrients such as calcium, vitamin D, and protein with non-dairy sources