Lactose is a sugar that occurs naturally in all forms of milk – full cream, low-fat, skim, evaporated and dried. Yoghurt and milk chocolate are also high. Ice cream, cottage cheese and cream are moderate sources while hard cheeses like Cheddar, Edam, Swiss and Parmesan are low.

Lactose intolerance occurs when the body is unable to digest this sugar, because of a lack of an enzyme in the small intestine. In normal situations, this enzyme (called lactase) breaks the lactose down, allowing them to be absorbed by the body.

Lactose intolerance is most common among certain racial groups such as Asian, Aboriginal, Mediterranean and Middle Eastern adult populations. It tends to be much less common in anyone of northern European descent. However it can often occur short term, say after a bout of gastroenteritis or during illnesses like coeliac disease or HIV infections.

Lactose check list

One of the most common misconceptions about intolerance to lactose is that it means no more dairy. The good news is that milk and other dairy foods - important sources of protein, calcium and B vitamins - don’t need to be completely eliminated.

The best advice is to eat lactose-containing foods as part of a meal rather than on an empty stomach. And reduce the amount you eat at one time. Eating ‘a little often’ is better tolerated than a large amount infrequently.

Look for 'No lactose' or 'lactose-reduced' milks in your supermarket. Both fresh and long life products are available.

Alternatively, some people find that a soy or rice beverage (which contain no lactose) works best for them. Make sure you choose a brand with contain added calcium, especially for children.