What is lactose intolerance?

Lactose intolerance is the inability to absorb lactose – the predominant sugar in milk – into the digestive system. If lactose is not absorbed properly, it ferments and this results in abdominal pain, a bloated stomach and diarrhea.

Lactose is composed of two other sugars bound together. In order for lactose to be absorbed, it must be split into two smaller sugars. This split is performed by an enzyme called lactase, which is present in the lining of the small intestine.

If the levels of the lactose enzyme are low or absent, then that splitting does not occur. The lactose is fermented by the bacteria in the large intestine and this produces excess gas and stomach rumbling and leads to diarrhea.

Lactase activity is high in babies and declines as the amount of milk in the diet decreases. Some people may have very low lactase levels but not have any symptoms. The reason for this is not known.

What are the symptoms of lactose intolerance?

  • Stomach rumbling, abdominal distension and increased wind.
  • Diarrhea.
  • Abdominal colic.
  • Nausea.

Which foods contain lactose?

  • bread and other baked goods
  • waffles, pancakes, biscuits, cookies, and mixes to make them
  • processed breakfast foods such as doughnuts, frozen waffles and pancakes, toaster pastries, and sweet rolls
  • processed breakfast cereals
  • instant potatoes, soups, and breakfast drinks
  • potato chips, corn chips, and other processed snacks
  • processed meats, such as bacon, sausage, hot dogs, and lunch meats
  • margarine
  • salad dressings
  • liquid and powdered milk-based meal replacements
  • protein powders and bars
  • candies
  • non-dairy liquid and powdered coffee creamers
  • non-dairy whipped toppings