Difference between Lactose and Lactase

Lactose and lactase may sound similar but they are two entirely different things with two different meanings. Lactose is a type of sugar and it belongs to the carbohydrate-sugar category, whereas lactase is an enzyme, falling into the protein category.

Lactose is generally used as an energy source and is commonly present in a lot of dairy products, including milk, butter and cheese. On the other hand, lactase is not used as an energy source.

Furthermore, Lactose is present in dairy products which we consume whereas lactase is an enzyme present in the small intestine. Its main purpose is to break the lactose present in the digestive track into two parts, glucose and galactose.

Lactose is created by two simple sugars, whereas lactase is created by a chain of amino acids in the intestine of the human body.

One of the main differences between the two terms is the fact that lactose is the substrate that enters the small intestine whereas lactase is the catalyst that causes the reaction which breaks lactose into galactose and glucose.

A person’s health can be affected if there is an excess of lactose in the body or a less than usual presence of lactase in the intestine.


  • 1


    Lactose was first discovered in the year 1619 and was confirmed as a form of sugar in the year 1780. It is a carbohydrate-sugar and is made up of glucose and galactose.

    Lactose is a common sugar which we consume on a daily basis and is used as an energy source in the body. It can be found in almost all of the dairy products that we consume, such as cheese, milk, butter and ice cream.

    The sugar also forms 2% to 8% of the milk we drink. It is extremely essential for growing babies.

  • 2


    Lactase is an enzyme which comes under the category of proteins. This enzyme is basically responsible for the hydrolysis of lactose in the human body. It is present in the small intestine and its main purpose is to break the lactose present into two main sugars. The lactase enzyme adds a water molecule to the lactose and breaks it into two components - glucose and galactose.

    Breaking the lactose into its two components is extremely important and failure to do so would result in stomach cramps and pain.

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