Lactose Intolerance: The Study of Enzyme Function and Why Milk Makes Some People Sick

byLacey Howard

Do you have problems digesting…

What is lactose intolerance?

• Regular milk contains a high concentration of lactose (and not glucose) and requires a special enzyme called lactase for digestion.

• Lactose intolerance is the deficiency in lactase to where your body produces little to none of the enzyme, causing the inability to digest lactose.

• If the lactose is not broken down into simpler sugars,

unpleasant symptoms may arise.

Symptoms of Lactose Intolerance

• Diarrhea

• Nausea, and sometimes, vomiting

• Abdominal cramps

• Bloating

• Gas

Treatment

How does lactase aid in the digestion of lactose?

Who is usually lactose intolerant?

• Eskimos• American Indians• sub-Saharan Africans• Mediterraneans • Near Eastern groups (i.e. Indian, Southeastern and

East Asian descent)• Jews• Pacific groups• 75% of the world is lactose intolerant

Who is usually lactose tolerant?

• Northern Europeans• Americans (due to mixing of ethnicities)• Milk-dependent pastoralists• Arabs of Saudi Arabia• Tussi of Africa

Theories as to why the lactase gene turns off

• Facilitate weaning and shorten a child’s dependence on the parent for lactation

• In adults, prevents competition of adults with infants for food

• Evolved as a defense mechanism against intestinal infections

How do glucose test strips work?

• Two special enzymes in the test strips react with glucose sugar only and not lactose

• The test strips will not react to regular milk that has not been treated with lactase enzyme, because regular milk has only lactose in it.

Q & A