Lactose Intolerance
What is it?
Lactose intolerance is a disorder of the digestive system that occurs when the body is not able to break down a sugar
molecule in cow milk called lactose.   It it a
food intolerance, not a food allergy.  Lactose is an important part of an
infant’s diet as it provides up to half of its energy needs, but is of unclear importance in adults.   Because of lactose’s
sweet properties, it is used in a variety of food products that you might not expect, such as candy, bread, and
sausages.   It is a common disorder that has strong genetic ties, affecting about 80% of black Americans, 50% of
Mexican Americans and 15% of whites.   In some Asian countries, almost 100% of the population is affected by the
disorder, while in Scandinavia the rate is only 2%.   Occasionally, individuals will develop lactose intolerance after
certain types of infections, such as a rotavirus infection.   Here, the lactose intolerance is temporary, and resolves once
the infection is cleared by the immune system.  

What are the Symptoms?
The typical symptoms of lactose intolerance include abdominal bloating, abdominal pain or cramping, passing gas
(flatulence), and loose stools or diarrhea.   Symptoms usually develop in early childhood in blacks and Asians while in
whites they occur in later childhood or adolescence.   Some people will develop symptoms quickly after eating small
amounts of milk containing foods, while others may tolerate larger amounts before having problems.  In general,
women describe worse symptoms than men.  Overall, most individuals can tolerate ½ to 1 cup (4-8 ounces) of milk if
eaten with other foods.

What Can I do?

  • Drink or eat small portions of cow milk containing products
  • Try full fat milk instead of low fat milk, or drink the milk as a chocolate drink
  • Eat yogurt with live bacteria—the bacteria appears to help the body digest the lactose
  • Eat hard cheeses such as cheddar, which have lower amounts of lactose
  • Eat other foods when you eat products containing cow milk.   This slows down the digestive process and can
    help decrease the symptoms
  • Try adding a lactase enzyme to your milk, or buy milk that has the enzyme already added to it
  • Make sure you keep a good calcium intake.  Calcium can be found in a variety of foods, including shrimp,
    broccoli, leafy greens, and canned salmon.  It can also be found in some cereals, breads, and orange juices.

Tuula H. Vesa, Philippe Marteau, and Riitta Korpela  Lactose Intolerance  J Am Coll Nutr 2000. 19: 165S-175S

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