Lactose intolerance: 'Is sourdough bread the cause of my lactose intolerance?

"Having read your answer about lactose intolerance, I wonder if I am suffering from it. I am getting abdominal pain, cramps and gas after I eat sourdough bread (which I bake myself). I do not eat dairy products, but I have heard that sourdough bread contains lactic acid. Could this be the cause?"

Dr Fred Kavalier answers your health question:

Lactose is a natural sugar that is broken down in the small intestine into two other sugars – glucose and galactose – which are absorbed into cells. If you are lacking in lactase, the enzyme that breaks down lactose, then the lactose will remain in the intestine. When it reaches the large intestine it begins to ferment, leading to the production of gases that cause wind, cramps and other symptoms. Sourdough bread does not contain lactose, so your symptoms must have another cause.

Please send your questions and suggestions to A Question of Health, The Independent, Independent House, 191 Marsh Wall, London E14 9RS; fax 020-7005 2182; or email health@independent.co.uk. Dr Kavalier regrets that he is unable to respond personally to questions.