Lactose Lab

What is Lactose Intolerance?

• When you are unable to digest lactose or milk sugar in dairy products.

• The problem: deficiency of lactase– An enzyme that breaks down lactose

Hydrolysis Reaction

Physiology of Lactose Intolerance

Evolution of Lactose

• Being able to digest lactose in adulthood is actually a genetic mutation.

• Most babies can digest milk without getting an upset stomach thanks to an enzyme called lactase. Up until several thousand years ago, that enzyme turned off once a person grew into adulthood — meaning most adults were lactose intolerant

Evolution of Lactose

• This development took 20,000 years to develop under extremely strong selective pressure.

Why did this develop so quickly?

Evolution of Lactose

• In Northern Europe, farmers that settled from the Fertile Crescent brought crops native to that region, which did not survive.

• This colder climate caused a “natural refrigeration” causing the people to drink the milk instead of eat it as yogurt.

• In times of famine, milk drinking increased.– If you lived, you pass on the genetic mutation.

Lactose Intolerance Around the World• Lactose intolerance is related to the use of dairy

products in the diet. In populations consuming a predominantly “dairy” diet, lactose intolerance is less common.

The Lactose Lab

• You will be adding the enzyme lactase to different types of milk to determine the effect of the enzyme on lactose.

• We will be using glucose test strips to determine if the lactose was broken down.