What Is Lactose Intolerance?

What Is Lactose Intolerance?

Your child may have a different type of reaction to cows’ milk, or formula made from it, called lactose intolerance. This is when their body can’t digest lactose, which is a type of natural sugar found in milk.

What causes lactose intolerance?

Lactose intolerance is caused by a shortage of lactase in the body, an enzyme produced by the small intestine that is needed to digest lactose. Certain digestive diseases (such as Crohn’s disease, ulcerative colitis, and celiac disease), stomach or intestinal infections, and injuries to the small intestine (such as surgery, trauma, chemotherapy, or radiation therapy) may reduce the amount of lactase available to process lactose properly. If the small intestine is injured, lactose intolerance may be temporary, with symptoms improving after the intestine has healed.

What are the symptoms of lactose intolerance?

Symptoms of lactose intolerance include nausea, cramps, gas, bloating, or diarrhoea within 30 minutes to 2 hours after consuming milk or dairy products. Symptoms occur because there is not enough lactase being produced by the body to digest the lactose consumed. The severity of symptoms varies, depending on the amount of lactose an individual person can tolerate. Some people may be sensitive to extremely small amounts of lactose-containing foods while others can eat larger amounts before they notice symptoms.

Undigested milk sugars

The enzyme lactase breaks down milk sugar (lactose). Lactase enzymes are found in the lining of the small intestine. They change the milk sugar into absorbable compounds – glucose and galactose.

If your body does not produce enough lactase, lactose is not digested and absorbed in the small intestine in the usual way. Instead, it continues to travel along the digestive tract to the large intestine, where bacteria partially break it down into acids and gases. This fermentation process causes excessive wind, bloating and associated pain.

Any undigested lactose continues along the intestinal tract. This lactose attracts water molecules. So rather than being absorbed into the bloodstream, water remains in the faecal matter (poo) and watery poo (diarrhoea) is the result.

Feeding and milk allergies

Managing a cows’ milk protein allergy involves removing all cow’s milk from your baby’s diet, so you’ll need to get familiar with reading food labels and ingredients as milk can occur in unlikely places. Food labelling laws are there to help you and common allergens, like milk, have to be declared on pre-packaged foods.

If your baby is being formula fed and has been diagnosed with cow milk protein allergy, your doctor may prescribe an extensively hydrolyzed formula. The protein in these formulas has been broken down into smaller pieces so that the baby’s immune system does not recognize it as an allergen – a process that does not affect the nutritional value of the formula.

If your baby is diagnosed with cows’ milk protein allergy and you’re breastfeeding, in rare cases your baby may be reacting to the milk proteins passing from your diet into your breastmilk. If this is the case you may have to change your diet – but this should only ever be done after consulting with your healthcare professional.

How to identify lactose intolerance in babies?

Primary (or true) lactose intolerance

This extremely rare genetic condition is incompatible with normal life unless there is medical intervention. A truly lactose-intolerant baby would fail to thrive from birth (ie not even start to gain weight) and show obvious symptoms of malabsorption and dehydration. This is a medical emergency and the baby would need a special diet from soon after birth.

Secondary lactose intolerance

Because the enzyme lactase is produced in the very tips of the microscopic folds of the intestine, anything that damages the gut lining can cause secondary lactose intolerance. Even subtle damage to the gut may wipe off these tips and reduce enzyme production, for example:

  • Gastroenteritis.
  • Food intolerance or allergy. In breastfed babies, this can come from food proteins, such as in cows’ milk, wheat, soy, or egg, or possibly other food chemicals that enter breastmilk from the mother’s diet, as well as from food the baby has eaten.
  • Parasitic infection such as giardiasis or cryptosporidiosis.
  • Coeliac disease (intolerance to gluten in wheat and some other grain products).
  • Following bowel surgery.

Food allergies and food intolerances can cause a baby to be unsettled. The foods to which a baby is allergic or intolerant can pass through the mother’s breastmilk. In some cases, removal from the mother’s diet of the foods to which the baby is allergic or intolerant, for example, cows’ milk products, can sometimes help. If you wish to try eliminating foods from your diet on the suspicion that your baby has an allergy or intolerance, check with a dietitian to help you identify the culprit foods and to make sure your diet is nutritionally adequate for both you and your baby.