Lactose intolerance

Do you frequently have a discomfort in your stomach after having milk or other dairy products? Then you may be having a condition called lactose intolerance. Lactose intolerance is a common problem related to the digestive system. In this condition, the body cannot digest lactose which is a common sugar found in milk and other dairy products.


Lactose consumed through foods is broken down into simple sugars (such as glucose and galactose) in the body by the enzyme called lactase. These smaller sugars get easily absorbed through the gut. There are a number of causes for lactose intolerance:

  • Familial history
  • Primary lactase deficiency: In these patients, the amount of lactase enzyme produced is not adequate. This is common after 6 years of age.
  • Congenital lactase deficiency: In these patients, there is a complete lack of production of the enzyme. This is seen immediately after the birth of the child but does not last for a long time.
  • Secondary lactase deficiency: When there is an injury to the cells lining the inner walls of the small intestine, it can reduce the production of lactase. It occurs more often in children after a stomach infection. It can also be a complication of chemotherapy or other bowel diseases.
  • Developmental lactase deficiency: After the birth of a baby, it takes some time for the production of adequate amounts of lactose. But in premature babies, born before 6 weeks to later, there can be low levels of lactase enzyme. This is called temporary lactose intolerance and disappears as the baby grows older.


Lactose intolerance symptoms develop within a few hours (usually after 30 minutes to 2 hours) after consuming the lactose containing foods and drinks. The severity of the symptoms and the time of occurrence depend on the lactose dose consumed. Symptoms of lactose intolerance include:

  • feeling sick
  • diarrhea (loose stools)
  • flatulence (accumulation of gas in the intestine)
  • bloated stomach
  • stomach cramps and pains
  • stomach rumbling

Risk factors

Lactose intolerance is more common in adults. Most of the cases are reported by people aged between 20 and 40 years.

Lactose intolerance in infants: Babies born with faulty genes associated with the production of lactase enzyme can become intolerant to lactose. Lactose intolerance is rare in newborns.


Lactose helps in the absorption of certain minerals (such as Magnesium and Zinc) which are important for strong and healthy bones. Also, lactose intolerant patients may have deficiencies of calcium, vitamins A, B12 and D and proteins due to lack of intake of dairy products. Consequently, such people may develop the below conditions:

  • Osteopenia – low bone-mineral density
  • Osteoporosis – thinning of the bones, which increases the risk of fractures
  • Malnutrition – inadequacy of nutrients which can weaken the immune system, make your feel tired or depressed

From your symptoms, if the doctor suspects lactose intolerance, certain confirmatory tests as detailed below are performed.

Test typePurpose of the test
Lactose intolerance test Blood tests are done to check the levels of glucose, 2 hours after administering lactose-filled drink. No change in the glucose levels may indicate indigestion of lactose.
Breath test Breath test is performed after administering lactose-filled drink to detect the hydrogen levels. Excess production of hydrogen gas than the normal indicates improper digestion of lactose.
Stool test In the case of infants and children, stool test is preferable. Undigested lactose upon fermentation produces lactic acid and other acids as detected in the stools.

Lactose intolerance treatment is so far not available. The best strategy is to avoid or limit taking milk and dairy products or by taking lactose-reduced milk and dairy products. Some of the lactose intolerant people can safely take yogurt without any problem.

Additionally, dietary supplements of lactase products may be taken to help with the digestion.

Lactose intolerance diet: One of the biggest concerns of people with lactose intolerance is about inadequate nutrients, especially calcium and is very important for children, pregnant women, and after menopause. Therefore, by including the below-listed foods in the diet, calcium deficiency can be overcome.

  • Almonds
  • Broccoli, collards, kale, okra, and turnip greens
  • Canned sardines, tuna, and salmon
  • Calcium-fortified juices and cereals
  • Calcium-fortified soy products (e.g. soy milk, soybeans, and tofu)