Lactose is the sugar found in milk and milk by-products.
It is a large sugar molecule that made up of two smaller sugar molecules, glucose and galactose. Lactose are split into these two smaller sugar molecules by an enzyme lactase in order to be absorbed by the intestine and into the body. It is used in pharmacy for tablets, in medicine as nutrient and sweetener in food industry.
Lactose intolerance is a common medical condition which can cause diarrhea, abdominal pain, and gas. It is caused by reduced or absent activity of enzyme lactase, therefore, lactose cannot be digested into the body.
Scientific References :
1. PubChem: https://pubchem.ncbi.nlm.nih.gov/compound/6134