What is Lactose Intolerance

What is Lactose intolerance ? Lactose intolerance is defined as the inability to tolerate milk and milk products, resulting from the deficiency of the enzyme lactase necessary for the digestion of the complex sugar lactose contained in milk.

  • Diarrhea, abdominal cramps and bloating, flatulence and urgent bowel movements following the consumption of dairy products are common symptoms.
  • Children with lactose intolerance usually have chronic diarrhea and fail to gain weight.
  • Deficiency of the enzyme lactase, resulting in the indigestion of lactose sugar, is the cause of this condition.
  • Appearance of typical symptoms following dairy consumption is the basis of the diagnosis.
  • Avoiding foods containing lactose or taking lactase supplements are the treatment options.

Lactose is the main sugar contained in milk, and is consequently present in all other dairy products in varying amounts. The glandular cells in the small intestine’s lining normally secrete the enzyme lactase exclusively for the digestion of lactose. The enzyme lactase is necessary to break down the complex lactose sugar into simple sugars galactose and glucose which are easily absorbed directly into the blood through the wall of the small intestine. When there is a deficiency of lactase, the milk sugar lactose is not broken down into its simpler constituents. When large amount of undigested lactose remains in the small intestine, fluid gets drawn in to facilitate the rapid passage of the undigested matter out of the digestive tract, resulting in diarrhea. In the large intestine, certain types of bacteria cause fermentation of the lactose producing gas and stools acidic in nature.

The main diet of new born babies and infants being milk, they normally have high levels of lactase enzyme. But the lactase levels significantly decrease as the child is weaned, especially in all the people of Asian origin and 80%of Hispanics and blacks. This results in varying levels of lactose intolerance in adults and older children belonging to these ethnic groups. Lactase production in whites of European origin is sustained throughout adult life; hence the incidence of lactose intolerance is as low as 15% in this group. However, it is estimated that more than three fourths of the world’s population has lactose intolerance and in the United States alone, around 50 million people may be having this condition.

There are other sugars such as sucrose and maltose contained in various foods, and intolerance to them can also occur, but it is not as common as lactose intolerance. Deficiency of enzyme sucrose and enzymes isomaltase and maltase result in sucrose intolerance and maltose intolerance respectively, as these complex sugars cannot be absorbed into the blood unless they are broken down into simpler sugars.


Abdominal cramps, bloating of the abdomen, flatulence, and nausea are the most common symptoms which appear on consuming lactose-containing foods. Loud bowel sounds referred to as borborygmy is another symptom. An urgent bowel movement within half an hour to two hours following lactose consumption is also common. Since all dairy products have lactose sugar in varying amounts, people who have lactose intolerance are not able to take milk or milk products. Because of the adverse reactions immediately following the consumption of lactose-rich foods, most people with lactose intolerance learn to avoid those foods which trigger the symptoms, without even being conscious of their condition.

When lactose intolerance is present in children, frequent diarrhea is a common symptom as their diet usually contains a lot of milk and milk products. Their weight gain may be affected as the condition causes rapid passage of food along the digestive tract, greatly reducing the intestine’s capacity to absorb nutrients from the food.

Symptoms of lactose intolerance are not as serious as those of some other malabsorption disorders such as tropical sprue or celiac disease. The symptoms are easily reversible too, on cutting off lactose-containing foods from the diet.

Diagnosis and Treatment

When a person complains of the symptoms typical of lactose intolerance after the consumption of milk or other dairy products, the doctor is alerted to the possibility of this condition. The patient is advised to follow a diet devoid of all types of dairy products for a period of 3 to 4 weeks. If the symptoms disappear during this period, it confirms lactose intolerance without any further testing.

Following a diet devoid of all lactose-containing foods can practically relieve a person of the symptoms of lactose intolerance, though it does not cure the condition. The enzyme lactase is commercially available as tablets which can make the lactose sugar digestible when added to milk. Dairy products which are lactose-reduced may be readily available in shops for the use of lactose intolerant persons. Deficiency of calcium resulting from the lack of dairy products in the diet should be prevented by taking adequate amounts of calcium supplements.

Share and Enjoy

  • Facebook
  • Twitter
  • Delicious
  • LinkedIn
  • StumbleUpon
  • Add to favorites
  • Email
  • RSS

Yasser Elnahas

MD, PHD, Professor Of CardioVascular Surgery
Dr. Yasser Elnahas, Is an associate Professor of Cardiovascular Surgery. Dr. Elnahas was trained as a fellow At Texas Heart Institute And Mayo Clinic Foundation.Dr. Elnahas is dedicated to educating the general public about different disease conditions and simplifying the medical knowledge in an easy to understand terminology.

Latest posts by Yasser Elnahas (see all)

You might also likeclose
WP Socializer Aakash Web