Simon Whistler, host of the informative video series “Today I Found Out” explained what causes lactose intolerance. Reasons include genetics (primary lactase deficiency) and illness (secondary lactase deficiency), both of which impede the body’s ability to digest lactose.
Lactose intolerance is simply the body’s inability to digest lactose. Lactose is a disaccharide, or a molecule made up of two types of sugars, in this case, glucose and galactose. Most people have an enzyme (a protein molecule that breaks down other molecules) lactase in their digestive systems. This enzyme breaks down lactose into glucose and galactose. The body can then absorb and use these sugars for energy. When someone has a lactase deficiency, lactose cannot be digested and remains in the digestive system causing a wide range of unwanted symptoms, including abdominal pain, gas, diarrhea, nausea, and a bloated stomach.