Lactose overload is not the same as lactose intolerance

It is not uncommon for babies to experience some gastrointestinal discomfort, such as excessive wind, diarrhoea and apparent abdominal pain. Lactose, the natural sugar found in both cow’s milk and breast milk, is an important source of energy for infants and undigested lactose can also have ‘prebiotic’ benefits in an infant’s developing gut.

However, lactose is also commonly assumed to be a trigger for these symptoms, with some babies appearing to improve by removing cow’s milk based infant formula or lactose, but such conclusions are often incorrect. Before assuming too much too soon, there are some important things to consider.

Breast milk is high in lactose

Mothers on a lactose free or dairy free diet, have the same amount of lactose in their breast milk compared to mothers on a high lactose diet. That is because lactose is produced by the mother. As such, any change to the mother’s diet will not alter the lactose content in her breast milk. If a mother attempts a dairy free diet to settle their baby and there is improvement, lactose cannot be the reason.

Lactose overload as a possibility

If breast milk supply is excessive, the higher breast milk volume a lactating mother is producing means that both the total amount of breast milk and the speed with which the breast milk moves through the infant’s gut increases. As a result, there is too much lactose in the gut too soon, and the infant has less time to digest all the lactose. Here, “lactose overload” can occur, triggering symptoms of gas, abdominal discomfort and diarrhoea. This does not mean the infant is lactose intolerant; rather, they will tolerate breast milk in a smaller volume. Smaller, more frequent feeds should improve symptoms in the baby.

Real lactose intolerance (called Primary Lactose Intolerance) is extremely rare in babies. It is caused by an ‘in-born’ inability to produce the lactase enzyme needed to break apart the lactose and make it ready for a baby to use for energy. The outcome of this type of congenital lactase deficiency is poor with extreme failure to thrive.

Premature babies may have reduced lactase enzyme and may benefit from lactase enzyme supplementation. Your healthcare professional will tell you more about this, as it relates to your individual needs.

Of note, lactase enzyme is actually in its peak at birth and does not decline, even in ethnic groups at risk of lactose intolerance, until at least age 5.

Secondary lactose intolerance could be considered, but you must treat the underlying cause.

Secondary lactose intolerance occurs when there is inflammation in the gut and requires medical investigation to determine the cause. It means for the short term, lactose may be contributing to gastrointestinal symptoms, but treating the underlying cause is the priority.

Protein allergy can trigger gastrointestinal inflammation. If there is an allergy, diagnosis is important and should be made under the care of a paediatric allergist. Removal of the allergen from the baby’s diet will reduce the inflammation and improve lactose tolerance.

Inflammation can also occur after a bout of gastroenteritis or due to an underlying disease of the intestinal tract. Assessment and treatment of the underlying cause will again reduce the inflammation and improve lactose tolerance.

So what do you do if you suspect your baby is lactose intolerant?

Before you make any changes to your diet, seek medical advice for a thorough assessment of your baby’s symptoms and potential causes to ensure there are no underlying concerns. If there is not, your paediatrician, paediatric dietitian, maternal child health nurse or lactation consultant will be able to help you work through the possibilities and provide you with some advice to assist your baby.

Article provided by:

Dr Jaci Barrett
Accredited Practising Dietitian