Lactose Intolerance
What is it?
Lactose intolerance is the inability to digest or metabolise lactose, leaving an abundance of lactose in the large bowel to be fermented by bacteria. The fermentation causes excessive gas production of hydrogen or methane and short-chain fatty acids. It causes abdominal bloating, excessive flatulence, diarrhoea and abdominal cramps.
We need lactase enzymes to digest and break down lactose. In lactose intolerance, there is a deficiency of lactase enzymes.
Lactose is commonly found in animal milk such as cow's milk, goat's milk and human milk. We have an abundance of lactase enzymes in infancy and early childhood. We lose lactase enzymes as we get older.
How common is it?
In the UK, one in ten children has lactose intolerance. It is also more common in Afro-Caribbean, Asian and Oriental population.
There are three types of lactose intolerance:
1. Primary lactose intolerance. As we get older, the production of lactase enzymes reduces. This occurs naturally over time.
2. Secondary lactose intolerance. It is caused by damage to the lining of the bowels such as with gastroenteritis, inflammatory bowel disease, coeliac disease and severe food allergy such as milk. Secondary lactose intolerance will improve after a period of exclusion of lactose-containing food.
3. Congenital lactose intolerance. This is an inherited condition when a baby does not have sufficient lactase enzymes in infancy. It is rare and can be serious.
What are the signs and symptoms?
Lactose intolerance often causes abdominal pain, cramps, diarrhoea, abdominal bloating, excessive flatulence and sometimes nappy rash due to accumulation of lactic acid causing irritation of the skin.
How is it diagnosed?
Lactose intolerance can be diagnosed by carrying out a lactose hydrogen breath test. The child will be asked to consume a lactose drink and will be asked to blow into a straw connected to the machine. There will be a rise in hydrogen level if the child has lactose intolerance. Unabsorbed and undigested lactose will be metabolised by the bacteria in the large bowel.
Stool-reducing substance is often positive and stool pH tends to be low. Qualitative lactase enzymes from the small bowel can be useful.
What is the treatment?
Treatment of lactose intolerance is avoidance of lactose-containing food, mainly dairy products.
Children with lactose intolerance sometimes can tolerate hard cheese but not soft cheese which contains a high amount of lactose. 10% to 20% of children's medicines contain lactose. Lactase enzyme supplement is useful for lactose intolerance sufferers who wish to consume lactose containing food.
Important notes:
Children with lactose intolerance will be able to consume lactose-free dairy products such as Arla brand lactose-free milk. Children who truly have cow's milk protein allergy or intolerance will not tolerate lactose-free cow's milk as this milk still contains cow’s milk protein.
Lactose intolerance does not cause bowel inflammation.
Children who has on-going bowel symptoms after contracting gastroenteritis may develop secondary lactose intolerance and will benefit from consuming lactose free food products.
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