Lactose Intolerance
EDP column by Dr Ketan Dhatariya

“Every time I have a glass of milk I seem to get tummy pain and diarrhoea. My GP says I have lactose intolerance. What is this?"

Lactose is a form of sugar found mainly in milk and dairy products. The bowel has chemicals called enzymes that help to break down and digest the sugar to allow it to be absorbed into the blood stream. This enzyme is called lactase. If the enzyme is  missing, or does not work very well, then the sugar stays in the bowel and passes down lower. Further along the bowel, there are lots of bacteria that ferment the lactose to form lots of gas. This gas can build up and cause the symptoms that you describe – in particular, cramps, flatulence bloating. Also, because the sugars remain within the bowel, they cause water to leave the cells and this causes the watery diarrhoea that can sometimes occur. These symptoms occur within 2 hours.

This condition occurs in up to 70% of people, with Asians and Africans most often affected. Occasionally, temporary lactose intolerance can occur after a bout of viral gastroenteritis. In this situation, the lining of the bowel is shed and with it, the lactase enzymes are lost. It can take several weeks for the enzymes to get back up to sufficient numbers to restore normal bowel motions. In this situation, there are a variety of things that can be tried – such as using lactose free milk (or a milk that has the missing enzyme added to it). However, some people think that by doing that, when ‘normal’ milk is restarted, that there may be a ‘rebound’ effect, temporarily making things bad again. However, others feel that staying on normal milk is also OK, because, eventually, the enzyme will recover and things will go back to normal.

Most people who have long term lactose intolerance learn to avoid dairy products early in life. Having the condition is not detrimental in any way, as long as there is adequate nutritional intake, and that the calcium that would normally be taken in from the dairy products is maintained from other sources.  In the USA – but not the UK - the enzyme can be bought over the counter to be taken whenever dairy products are eaten or drunk.

It is important to read food labels because although lactose is mainly found in dairy products, it is often used in non-dairy products to provide texture, flavor and adhesive qualities to food. If you see the terms ‘whey’, or ‘milk solids’ , beware!

As always, if you have any concerns talk to your pharmacist or doctor.

For more information about Lactose Intolerance click this link: