Lactose Intolerance – Cause, Symptoms and Treatment – Dr. Vikas Singla

Since childhood, we are fed in our minds that milk is the most important part of our diet and must be consumed without fail. Since it contains all the essential nutrients, it is considered a complete food as per our understanding and we insist ourselves to drink milk. But, many people are not able to digest the milk as they are unable to fully digest the sugar(lactose) present in food products containing lactose. In general, Lactose intolerance is a syndrome having different symptoms like bloating, diarrhoea, and gas that arises after the consumption of foods containing lactose.

Lactase is an enzyme that is produced by the . Lactase helps to break down the lactose in the food into simple sugars (Glucose and Galactose) which can then be absorbed by our body. In people with lactose intolerance, lactase activity is reduced in the brush border of the small bowel mucosa which results in the incomplete breakdown of lactose. Lactose in food is passed into the colon in undigested form, where the gut bacteria interact with lactose, ferment it, and produce lactic acid and other chemicals, and the acidic substances, in turn, cause symptoms like abdominal pain, bloating, flatulence and diarrhoea. The severity of the symptoms may vary from individual to individual. These symptoms could be misunderstood with symptoms of cow’s milk allergy and therefore a better understanding is needed to rule out ‘milk allergy’ from ‘lactose intolerance’.

Who all can suffer from Lactose Intolerance?
Both children and adults can suffer from Lactose Intolerance.

Can Lactose intolerance be passed from parents to children?
Yes, we are likely to inherit lactose intolerance from our parents. It runs in families and can be genetically passed on from one generation to the other.

What Causes Lactose Intolerance?

    • It often runs in families.
    • After an injury /disease/infection of the small intestine.


What are the symptoms of Lactose Intolerance?small intestine

The symptoms may start after 30 minutes to 2 hours after we consume the food containing lactose.

How to diagnose Lactose intolerance?
The doctor will review the past history about the health and family of the patient along with examination.

For a definitive diagnosis, a few tests as mentioned below are recommended.

Lactose Tolerance Test: It looks for the glucose levels in the blood. Blood glucose levels will rise if the enzyme lactase breaks down the lactose into glucose. The patient is expected to fast for 8hours before the test. He/ She is made to drink a liquid containing lactose. Blood samples are taken over a period of 2-3 hours. No change in the blood sugar levels indicates that the patient may be lactose intolerant.

Hydrogen breath test: In the absence of lactase, the lactose is not absorbed in the small intestine and is passed to the colon. The bacteria present in the colon ferment the lactose and release hydrogen gas, which then passes out from the lungs. 7-8 samples of breath are checked after the consumption of lactose-containing liquid. Increased levels of hydrogen indicate that the patient is lactose intolerant.

Stool acidity test: This test is used for infants and young children who are not able to perform other tests. In the absence of breakdown of lactose in the small intestine, it gets fermented in the colon, producing lactic and other acids. Increased levels of lactic acid in the stool is an indication of lactose intolerance.

How is Lactose intolerance treated?

• Change in the diet: A complete/partial avoidance of food items containing lactose can help in reducing the symptoms.

Some tips to live with Lactose intolerance

  • Read the food labels properly.
  • Many people can tolerate a certain amount of lactose, so need not avoid it completely from the diet.
  • Try to include milk substitutes in the diet like almond milk, soya milk, and others in consultation with the doctor.
  • Calcium supplements to be taken if recommended.
Dr Vikas Singla
Director And Head,
Center For Gastroenterology, Hepatology And Endoscopy
Max Superspeciality Hospital, Saket New Delhi, India



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