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Lactose Intolerance: Symptoms, Causes, And Treatment

What is lactose intolerance?

Lactose is a type of sugar that is present in milk and milk products. This sugar is easily digested when we are infants and is the main source of nutrition at that stage. Although in rare cases, infants may be lactose intolerant. As people get older, a large percentage have lesser quantities of an enzyme called lactase which is needed to break down lactose. This causes the lactose to remain in the bowel and absorb more water leading to watery stools.


Is lactose intolerance the same as milk allergy?

No. Lactose intolerance is different from milk allergy. Lactose intolerance is caused by simply the lack of digestion and not because of an inflammatory reaction. Milk allergy is caused by an allergic reaction, usually to proteins present in the milk. Milk allergy is far more serious and can lead to severe reactions like anaphylaxis that can be life threatening.


What are the symptoms of lactose intolerance?

68% of people around the world are said to have some amount of lactose intolerance. Most people can tolerate some amount of lactose, but may start developing symptoms when the quantity consumed exceeds the limit.


The symptoms usually manifest as a sudden urge to use the bathroom about half an hour to two hours after consuming milk or milk products. The symptoms may include one or many of the following:

  • Bloating
  • Flatulence
  • Rumbling
  • Nausea
  • Diarrhoea
  • Belching
  • Pain in abdomen


If the person has been having diarrhoea, he/she may also develop dehydration. It is important to drink plenty of water if you suffer from diarrhoea.


When should you see a doctor?

If you experience the above mentioned symptoms, it is important to get it checked by a doctor because the symptoms are very similar to those of other conditions that need attention like irritable bowel syndrome or milk protein intolerance.


How is lactose intolerance diagnosed?

You may simply be asked to remove dairy products from your diet and wait for a while if your symptoms are minor. Some diagnostic tests may also be recommended such as:

  • Hydrogen breath test - After overnight fasting, hydrogen levels are measured in inhaled air after consuming lactose. If the hydrogen levels are high, it usually means you are lactose intolerant.
  • Lactose tolerance test - Checking blood glucose periodically after taking lactose. Lactose intolerant people will not show a rise in glucose as expected because digestion of lactose does not occur properly.
  • Stool sample - Infants may be recommended a stool sample test. The test is done to detect high levels of some fatty acids and a compound called acetate.


If your symptoms are severe, your doctor may recommend other tests to rule out other problems.


How is lactose intolerance treated?

  • The simplest solution is to cut down on food and drink that contain milk or products derived from milk.
  • There are usually lactose-free alternatives available in the market such as:
    • Lactose-free milk
    • Soy milk
    • Yogurt (where lactose has been broken down already)
    • Rice, oat, coconut-based milk
  • If you have mild tolerance for lactose, you may be recommended to space out your milk/milk-product consumption throughout the day to improve your tolerance.
  • Since milk is a rich source of Vitamin D, your doctor may recommend calcium and Vitamin D supplements to compensate for the loss from avoiding it.
  • Lactase substitutes that temporarily provide the enzyme required to digest milk may be advised to be taken with milk-based diets to improve digestion
Dr. Mrityunjay Kumar
Internal Medicine
Meet The Doctor
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