Who is affected by lactose intolerance?

It is estimated that 30 to 50 million Americans have some degree of lactose intolerance. Lactose intolerance affects people from certain ethnic populations and races—such as Latin Americans, African-Americans, Native Americans, Asians, East Europeans and Middle Easterners—more than others.

How do I know if processed foods contain lactose?

When buying food, read the ingredients on food labels carefully. Ingredients derived from milk that contain lactose include:

  • Whey
  • Caseinates
  • Nougat
  • Cheese
  • Milk by-products
  • Casein
  • Dry milk solids
  • Lactose
  • Butter
  • Curds
  • Nonfat dry milk
  • Dry milk powder

Also avoid items that state "may contain milk" on the food label. Depending on the severity of your symptoms, you may need to avoid or limit foods containing these ingredients.

Lactose is also present in about 20% of prescription medications, such as birth control pills (oral contraceptives), and about 6% of over-the-counter medications, such as some tablets for stomach acid and gas. ViactivÒ calcium chews contain lactose and should be avoided while following a lactose-free diet.

These medications usually affect only people with severe lactose intolerance. Ask your healthcare provider which medications contain lactose, and read the labels on over-the-counter medications to check their lactose content.

What causes lactose intolerance?

Some causes of lactose intolerance are known. Certain digestive diseases, such as Crohn's disease, ulcerative colitis, celiac sprue (an inherited disorder affecting the lining of the small intestine), other inflammatory bowel diseases, and injuries to the small intestine (surgery or trauma) may reduce the amount of lactase available to process lactose properly. If the small intestine is injured, lactose intolerance may be temporary, with symptoms improving after the intestine has healed.