Milk Tolerance In Humans: Most of the adults find it difficult to digest, Lactose the sugar in milk. This is because the gene, that code for the enzyme Lactase, is switched off. Lactase breaks lactose into of glucose and galactose. Glucose and galactose the easily digestible forms of sugar.
Lactose intolerance also known as hypolactasia or lactase deficiency. Its major symptoms are symptoms abdominal pain, bloating, flatulence, diarrhea, nausea and acidity.
The reaction catalyzed by lactase is:
C12H22O11 + H2O = C6H12O6 + C6H12O6 + heat
Most mammals normally become lactose intolerant after children gradually deprive of mother's milk, whereas some human populations have developed lactase persistence and have lactase production continues into adulthood. It is assumed that 75% of adults worldwide have lactose intolerance.
In some individuals, this decline usually begins by two years of age whereas in some individuals it does not start to occur until they are twenty years old. Lactose intolerance is very common in some parts of East Asia, Africa and among Native America and Northern Europe.