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Parent’s Guide: Lactose Intolerance in Children

Dr. Mahwish Nadir

3 min read

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If your child complains of a stomach ache or an upset stomach following milk intake, or after eating ice cream, you could wonder if lactose intolerance is to be blamed. But what exactly is lactose, and what causes its intolerance to develop in the body? This article discusses lactose intolerance in children and the relevant measures that can be taken to manage it effectively.

Read on to know more about it:

What is lactose?

Lactose is the disaccharide sugar, found in dairy products like cheese, milk, and yogurt. The enzyme in the digestive system, called lactase, degrades and breaks down the lactose sugar into its simple components: glucose & galactose for absorption into the bloodstream. 

What happens in lactose intolerance?

In lactose intolerance, the body lacks the enzyme lactase or the lactase enzyme is ineffective in digesting & absorbing lactose sugars. Consequently, the undigested lactose passes to the large intestine whereby it is fermented by the gut bacteria. The byproducts of the latter reaction—the majority of which is carbon dioxide and hydrogen, have a laxative effect, resulting in diarrhea or flatulence on the consumption of lactose-based products. 

What are the symptoms of lactose intolerance in children?

In children, the symptoms of lactose intolerance can begin as early as two years of age. They can start half-hour to two hours after intake of lactose-based products like milk. While symptoms may be different for every child, a few of them are commonly found such as upset stomach and diarrhea. Invariably, there can be cramps, bloating, nausea, and abdominal pain. In older children, vomiting is more common.

What are the types of lactose intolerance?

The following are the different types of lactose intolerance that can either be acquired or a person can be born with the deficiency of lactase.

Acquired lactose intolerance:

After childhood, there is a natural decline in lactase activity in the intestines. According to an estimate by the National Institutes of Health, almost two-thirds of people with lactose intolerance have acquired intolerance.

Primary lactose intolerance or lactase deficiency:

This is the name given to the complete absence of lactase enzyme in babies. On given breast milk, such babies develop severe diarrhea and have to be shifted to lactose-free formulas.

Secondary lactose intolerance:

Following a severe gastric infection, such as rotavirus or giardiasis, an individual may face a temporary intolerance of lactose as the intestinal villi are affected. As the infection clears and the villi regrow, the enzymatic activity returns. During this period, patients have nausea, most often followed by diarrhea and vomiting if they consume lactose-rich foods. 

How to diagnose lactose intolerance?

For lactose-intolerant children, a physical examination, complete history of the disease combined with a few investigations by the healthcare provider form a concrete diagnosis for lactose intolerance. Commonly, the investigations include:

Lactose intolerance test:

This investigation checks the level of lactose absorbed by the digestive system of the fasting patient when given a lactose-rich drink. In the next 24 hours, the stool is tested for the presence of lactose, and a percentage is obtained of the lactose given and the lactose absorbed. In lactose intolerance, there is a high amount of stool lactose content as the body is unable to absorb it.


This investigation involves viewing the cells of the small intestine after retracting a small sample. An upper endoscope is used to get the sample. In lactose intolerance, biopsy samples will show intestinal villi with a lack of the enzyme lactase.

Hydrogen breath test:

The patient is given a lactose-rich liquid and thereafter hydrogen level is tested in the breath at regular intervals. In lactose intolerance, the hydrogen levels are high. This hydrogen is the result of fermentation reactions by the gut bacteria in the large intestine. 

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Who is at the risk of lactose intolerance?

Some babies are at higher risk for lactose intolerance, including those that are born earlier than their due date—premature babies. The intolerance, however, in such babies is temporary and goes away after a short period of time. The incidence of lactose intolerance is higher in babies with a positive family history as well. Naturally, the genetic trait of lactose intolerance in such babies is passed on from one or both parents and the symptoms can present early or later in life—during adulthood or teenage.

How to manage lactose intolerance in children through dietary changes?

Following tips can be used to manage lactose intolerance in children:

  • Limit the intake of lactose-containing foods in your child. Thereafter, slowly add milk and milk products to their diet and check for any symptoms. Maintain a food diary to see which foods are tolerated by the child, and which foods cause worsening. Start with foods containing lower lactose content; these include yogurt and hard cheese. 
  • Try giving your children milk & milk-based products with other foods; this can lessen the intensity of symptoms. For instance, you can give the children cheese with crackers, or milk with cereal. If this is not tolerable, shift to lactose-free milk and milk-based products. In such products, the lactase enzyme is added to digest the lactose sugars. 
  • Ask your healthcare provider about lactase enzymes. Lactase is available as pills & drops that can be taken with milk and other lactose-based products. Lactase enzymes can lessen and prevent the symptoms through the digestion of lactose. 
  • In lactose intolerant patients, there are high chances of calcium deficiency as products like milk and cheese have a high calcium content. Avoiding milk & milk-based products can result in less calcium intake and consequently weaker bones. Be sure to supplement the calcium through other sources based on age and recommended dietary amount (RDA). In children up to six months of age, the RDA is 200 mg; from six months to one year, the RDA is 260 mg; from 1 to 3 years, the RDA is 700 mg as the calcium is needed for bone growth. The RDA increases to 1000 mg during the ages 4 to 8, and to 1300 mg per day between ages 9 to 18 years.

Opt for a varied and nutritious menu for yourself and your family to ensure proper health. Book an appointment with top nutritionists in Lahore, Karachi & Rawalpindi through Oladoc or call our helpline at 042-3890-0939 for assistance and find the RIGHT professional for your concerns.

Disclaimer: The contents of this article are intended to raise awareness about common health issues and should not be viewed as sound medical advice for your specific condition. You should always consult with a licensed medical practitioner prior to following any suggestions outlined in this article or adopting any treatment protocol based on the contents of this article.

Dr. Mahwish Nadir
Dr. Mahwish Nadir - Author Dr. Mahwish Nadir is a Pediatrician in Karachi with 9 years of experience. You can consult Dr. Mahwish Nadir through oladoc.com or by calling at 02138140600.

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