I've had digestive problems since my early twenties, and have been diagnosed with irritable bowel syndrome and "non-functional dyspepsia". A couple of years ago, in desperation, I tried a blood test for food intolerance, although I consider the ailment faddish. It indicated a low-grade intolerance of wheat and dairy. To my irritation and relief, if I cut out wheat and restrict dairy, I can drop my medications and feel better than when taking them. Now a friend has suggested that I might have "leaky gut syndrome", which has a plausible-sounding explanation for food intolerance. But when I Googled it, none of the sites were mainstream medical sites, and most sold costly supplements. Is this a real syndrome or a marketing ploy?

Dr Fred Kavalier answers your health question:

Leaky gut syndrome has certainly made it on to Google in a big way, but it hasn't yet appeared in the medical literature. The idea behind it is that the tiny spaces between the cells that line the intestine get too big and allow substances such as toxins and bacteria into the body. This is said to produce many illnesses, from fibromyalgia to food allergies.

Alternative practitioners say that mainstream doctors fail to recognise the syndrome. In fact, there has been substantial research into leaky guts. People with Crohn's disease have leaky guts; so do people with severe alcoholic liver disease. But there is no sound evidence that "leaky guts" lead to irritable bowel syndrome (IBS), food allergies or gastritis.

If you feel better when you avoid wheat and dairy products, avoid them. Ask a friend to give you something that contains wheat without your knowing - if the symptoms recur, you are probably intolerant.

Please mail your questions for Dr Fred to health@independent.co.uk. He regrets that he is unable to respond personally to questions.