Lactose Free MilkCredit: photo by Cheryl Weldon

Many people suffer from a condition of lactose intolerance and must be careful regarding what dairy products they consume.  In response to this need, the dairy industry began producing lactose free milk.  What is lactose and how is lactose removed from milk and other dairy products?

 What is Lactose?

 The quick definition of lactose is it is a disaccharide sugar which is found in milk.  For the layperson, this means little and needs more explanation.  First one must know what a monosaccharide is and how it relates to a disaccharide.  A monosaccharide is the most basic unit of a carbohydrate which in turn means it is the simplest form of sugar. A disaccharide is a carbohydrate unit formed when two monosaccharides undergo a condensation process (water is removed). Lactose is milk sugar and is made of the two monosaccharides glucose and galactose.

Lactose in milk accounts for about two-eight percent of the weight.  Since cheese is made from milk, it too contains lactose, though usually not as much.  Cheese is made from whey which is the remaining liquid after milk is curdled and strained.  The whey contains a little fewer than five percent lactose by weight.

 Lactose in milk was discovered by Fabriccio Bartoletti in 1619; but not identified as a sugar until over a hundred years later when Carl Wilhelm Scheele did so.  Lactose is often used in the pharmaceutical arena as a filler for pills.  The food industry uses lactose for several purposes for example as a stabilizer of aromas.

 How is Lactose Free Milk Made?

 Contrary to belief, lactose is not actually removed from products.  Instead, manufacturers alter the composition of lactose by converting it into more easily digested molecules.  They do this by adding a chemical to lactose.   Lactose free milk is produced by adding small amounts of lactase, an enzyme the human body produces to aid in digestion.

 When the lactase is added, the lactose reacts by dividing back into the glucose and galactose molecules. This will make the lactose-free milk taste a bit sweeter because glucose and galactose bind tightly to the taste buds whereas lactose does not.  Not all dairy products need additional processing to be lactose-free.  Some, such as yogurt already have a built in process; yogurt’s bacteria makes the chemical reaction.

 Lactose Intolerance

 Intolerance to lactose can happen at any age.  People may have no problems with lactose and later in their lives begin to experience symptoms of lactose intolerance.  These symptoms include stomach bloating, gas, cramps, nausea or diarrhea after drinking milk or eating other dairy products. 

 Intolerance of this milk sugar comes from the body producing  an inadequate amount of the enzyme lactase.  Lactase is what breaks down and metabolizes the lactose in milk.  This happens in the duodenum and if there is not sufficient lactase, the lactose molecules are passed into the colon intact where they are fermented and cause the discomforting problems.

 Lactase deficiency is diagnosed as one of the following:

  • Primary: this is the most common and is genetic. It only attacks adults and is caused by the absence of a lactose persistent allele.
  • Secondary, acquire, or transient: this deficiency is caused by injury to the small intestine and usually occurs in infancy.
  • Congenital: this is a very rare genetic disorder occurring on a recessive non-sex chromosome that prevents lactase production from birth. 

 Lactose-free products are easily consumed by those with intolerance because the lactose has already been digested into its two monosaccarides; therefore no lactase enzyme is needed to digest the product.  The intestinal tract can absorb these smaller sugars directly into the bloodstream, thus avoiding symptoms of lactose intolerance.  Alternatives to lactose –free milk is consuming milk substitutes such as soy milk, rice milk or almond milk.





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