Dr. Avi Lemberg
Head of the Department of Paediatric Gastroenterology
Sydney Children’s Hospital at Randwick
What is lactose and lactose intolerance?
Lactose is a disaccharidewhich is a molecule that is made up of two simple sugars to make a larger simple sugar. Lactose intolerance is where the body cannot break down the lactose. There are small finger-like projections on the surface of the small bowel, which is the part of the bowel after the stomach, that help absorb nutrients. Small sugars such as lactose are broken down by enzymes that lie on top of the villi. These enzymes break down lactose so that they can be absorbed across the villi and used as energy by the body. Lactose intolerance occurs when there is not enough of these enzymes (in this case lactase) to break down all the lactose that is being swallowed by a child.
How do you diagnose lactose intolerance in babies?
Lactose intolerance is diagnosed generally just on history alone whereby children or babies are given lactose and this results in diarrhoea, gas and bloating. There are more definitive ways of diagnosing lactose intolerance such as the presence of reducing substances in the stool which can give one an idea that there might be lactose intolerance or intolerance of another sugar. The definitive diagnosis of lactose intolerance can be made by biopsying the small bowel and measuring the levels of lactase (which is the enzyme) on the border of the villi. Human milk does contain lactose and of course one needs simple sugars in order to survive as this is what gives us our energy so that we can live from day to day. Many formulas contain alternative sugars which can be absorbed, so lactose is important but not vital for life.
Does lactose help the balance of bacteria in my baby?
Lactose will change the balance of bacteria particularly if one cannot absorb lactose terribly well. This will allow the lactose to be used by the bacteria to multiply and therefore change bacterial populations and thus the gut flora. In the main the lactose feeds the gas forming organisms (bacteria) in the gut which leads to some of the symptoms of lactose intolerance such as windy pain, bloating and gas being passed from the bottom end.
Can probiotics and prebiotics help by baby’s gut flora?
Yes, probiotics and prebiotics can help with gut flora in changing the different types of bacteria. In particular, they can help reduce the numbers of bacteria that are gas forming, that are increased by the presence of too much lactose in the bowel. The probiotics may compete with the gas forming organisms for food and thus reduce the numbers of those organisms that cause the gas and bloating and windy pain.
Will my baby tolerate lactose after diarrhoea?
Lactose can be difficult to tolerate after diarrhoea because diarrhoeal infections often result in breaking down of the finger-like projections (the villi) on the border of the small bowel. Thus, this reduces the amount of lactase in the bowel and therefore leads to a relative lactose intolerance that can last for days or sometimes even weeks.
Should I keep breastfeeding if my baby is lactose intolerant?
Yes, one should keep breastfeeding as much as possible even if you do have a baby that has a relative lack of lactase. Lactose intolerance tends to be temporary and with time lactase will increase. Obviously, there are some babies that have a very low amount of lactase and therefore their lactose intolerance leads to severe symptoms and they may have to stop breastfeeding and start a lactose-free formula for a short period or sometimes even for prolonged periods.
I am formula feeding – should I switch formulas?
If your child is having severe symptoms of lactose intolerance while being formula fed, it is certainly worth a trial of a lactose-free formula to see if this will improve symptoms.
If I switch to a formula for lactose intolerance after baby’s diarrhoea, do I need to go back or do I stay on the lactose-free one?
Generally lactose intolerance only lasts for short periods. The villi tend to grow back fairly rapidly over days but perhaps sometimes this can take weeks. Generally, one only needs to be on a lactose-free formula for a few weeks after a gastrointestinal infection.
This article is written by an external expert. We advise speaking to a doctor or dietitian before altering or changing your normal feeding regimen.
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