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What is lactose?


Selection of non-dairy milk alternatives in different bottles. Lactose free milkLactose is a carbohydrate found in milk and some processed foods consisting of two monosaccharides. This carbohydrate is split into glucose and galactose by the ferment known as lactase. Later these particles are trapped by the sodium-dependent glucose carrier that helps to carry the saccharides into the cells. Sometimes the production of this enzyme is insufficient, in this case, lactose intolerance occurs – a person is unable to digest lactose, the carbohydrate present in milk. This disorder is quite common worldwide. Interestingly, babies usually have high levels of the enzyme which later subside as the child grows and isn’t being breastfed. Lactose intolerance prevalence is the highest among individuals of Asian, South American, and African descent (it is considered that about 75% of adults have decreased ability to digest lactose), while those who come from the northern countries are more likely to preserve their lactose production and respectively are able to consume and digest milk.

Lactase deficiency is one of the most common and most significant conditions that affect the carbohydrates metabolism.

Types of lactase deficiency

  • Primary lactase deficiency is genetically determined. Two genes – the lactase-phlorizin hydrolyze and the MCM6 gene located on the long arm of the chromosome 21 are responsible for controlling the synthesis and activity of lactase enzyme;
  • Secondary lactase deficiency develops as a result of the diseases that affect the intestinal mucosa such as the celiac disease, small intestinal bacterial overgrowth, acute gastroenteritis, giardiasis, ascariasis radiation enteritis, Whipple syndrome, Kwashiorkor, etc;

Symptoms of lactose intolerance

Lactose intolerance may be suspected when the following symptoms are present a few hours after the consumption of milk and dairy products:

  • Abdominal pain and bloating;
  • Nausea;
  • Flatulence;
  • Diarrhea (although it occurs relatively rarely);

How to diagnose lactose intolerance

  • As long as at some point lactose insufficiency is genetically determined, genetic testing may be used to diagnose the condition.
  • The lactose breath hydrogen test is the most widely used test to determine lactase deficiency, this noninvasive test helps to verify lactose malabsorption – the amount of specific Hydrogenum in the exhaled air is measured after lactose consumption;
  • Lactose tolerance test is used quite rarely. This test implies the serial measurement of blood glucose following the consumption of lactose. When the blood glucose levels don’t rise lactose intolerance may be diagnosed;
  • Some procedures such as bowel biopsy, CT or MRI and other special lab tests may be performed if the secondary lactose intolerance should be ruled out;

Treatment and diet

Complete elimination of milk and dairy products consumption restriction helps to relieve the symptoms. Cheese has lower quantities of lactose, therefore, it may be consumed safely, whereas milk and ice-cream are rich in lactose.

Lactase enzyme supplements are also available. These medications such as Lactaid and Dairy-ease may be taken to alleviate the digestion of lactose-containing foods, although they cannot be used regularly. Liquid lactase preparations also exist. They are added to milk and placed into the fridge overnight. In the morning milk lactose is already hydrolyzed and milk can be consumed. Furthermore, dairy products with predigested lactose may be found in the groceries.

On the other hand, in the case of secondary lactase deficiency, it is essential to find out what is the causative disorder and treat it.

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