Lactose Intolerance affects a sizeable number of the world population – both adults and children. Asians, in particular are genetically lactose intolerant as they lack the lactase enzyme required to digest lactose.
We quizzed Dr. James Huang, Consultant, Division of Paediatric Gastroenterology, Nutrition, Hepatology and Liver Transplantation, Department of Paediatrics, Khoo Teck Puat – National University Children’s Medical Institute, National University Hospital on the subject of lactose intolerance in children.
Read Dr. Huang’s insightful answers below:
What is lactose intolerance?
Dr. Huang: Lactose intolerance is a form of carbohydrate intolerance. It refers to the inability to digest lactose, a sugar or carbohydrate found in dairy products. This is due to a lack of lactase enzyme found in our small intestine. This is not the same as a cow’s milk allergy which tends to happen in young infants and children, where there is an allergic reaction towards the cow milk protein.
On the contrary, primary lactose intolerance tends to occur the older we get, especially in the Asian population. This is because of genetic factors. It is estimated more than 90% of the Asian adult population will eventually be lactose intolerant, although the severity of symptoms varies between different individuals. As we age, the amount of lactase enzyme activity in our small intestine declines. Lactose intolerance can start as early as the age of 4 and progressively increases in incidence with age. It must be emphasised in primary lactose intolerance, the physical health of the individual and his or her intestinal structure should be otherwise normal. This means the child should not experience worrisome symptoms such as weight loss, anaemia etc.
Lactose intolerance can also be a temporary phenomenon after a bout of food poisoning or gastrointestinal infection. This is because the infection temporarily reduces the amount of lactase in our small intestinal wall. The intestine will eventually regain its ability to digest lactose in a few weeks in those cases.
Rarely, lactose intolerance is secondary to an underlying medical condition damaging the intestine (disorders of the immune system affecting the bowel such as inflammatory bowel disease or celiac disease). Typically these individuals would also have other symptoms and signs that point towards an underlying medical problem eg. weight loss, anaemia, fevers, loss of appetite, lethargy etc.
- How to recognize lactose intolerance in children?
Dr. Huang: Children would have symptoms of ‘indigestion’ minutes to hours after a lactose-containing meal or drink. These symptoms can range from abdominal pain/discomfort, bloating, flatulence and flatus and/or watery diarrhea. This is because in lactose intolerance, the undigested lactose sugar in the intestine undergoes fermentation, producing a lot of gas. The undigested lactose also has an osmotic effect i.e. acting like a sponge, attracting water into the intestine and causing watery stools/diarrhea.
- What is the best way to manage lactose intolerance?
Dr. Huang: If lactose intolerance is suspected, the best way is to see if the symptoms of ‘indigestion’ resolve with lactose avoidance and/or consumption of a lactase enzyme supplement prior to the lactose-containing product. Lactose is found in all mammalian milk products. Certain fermented dairy products such as yoghurt and cheese may contain less lactose as the fermentation process breaks down the lactose. This explains why a lactose-intolerant individual may tolerate fermented dairy products better than fresh dairy products.
Hence, lactose avoidance can be done through consumption of a lactose-free product (soy, plant-based milk) or consuming a lactase enzyme supplement prior to consumption of a lactose-containing food/drink product.
- What kind of diet is advised for children who are lactose intolerant?
Dr. Huang: As above – lactose free or lactase consumption prior to a lactose-containing product. Different individuals may tolerate different amounts of lactose before developing symptoms.
- Should children stop consuming all dairy products, if they are lactose intolerant?
Dr. Huang: While consumption of lactose in a lactose intolerant child may make them feel uncomfortable with all the symptoms of ‘indigestion’, lactose itself would not cause harm or damage to the intestine. Hence, it is not necessary they avoid dairy products strictly.
The advice would be to see how much and what kind of dairy product can be tolerated by the child or individual. Some lactose intolerant individuals can tolerate limited amounts of lactose or they may tolerate fermented forms of dairy products. There are also lactose-free options on the market and/or lactase supplements so the child can continue consuming their favourite dairy products.
- How can children get benefits of dairy (such as calcium) if they don’t consume milk/ milk products?
Dr. Huang: There are a variety of foods that are rich in calcium (e.g. tofu/soy, dark leafy vegetables and ikan bilis). Children can also consume lactose-free milk which offers all the nutritional benefits of fresh milk without lactose.
- Do children outgrow lactose intolerance?
Dr. Huang: Only if the lactose tolerance (see above) was a temporary phenomenon after a bout of food poisoning/gastrointestinal infection. Otherwise, primary lactose intolerance would tend to remain once it has started. This is due to a genetic deficiency of the lactase enzyme in Asians and you cannot outgrow your own genetics.
Can medicines/ supplements help counter effects of lactose intolerance? Can lactase enzyme tablets be taken long-term?
Dr. Huang: Lactase enzyme supplements are safe because they replace the deficiency of the lactase enzyme in the small intestine. They can be taken in the long term safely prior to consumption of lactose products, in the lactose intolerant individual.