I was interested to read of a recently developed diagnostic tool for doctors - the artificial nose. Scientists at Strathclyde University have come up with a device that can detect odours characteristic of a variety of medical conditions. Learning of this newfangled gadget reminded me of a story my mother once told me regarding a doctor with whom she had worked in the Fifties. Her colleague, a surgeon by trade, was renowned for his ability to accurately diagnose internal cancer on the basis of the smell emanating from his patient. This anecdote does seem to provide some support for the notion that it is possible to sniff out illness.

The fact that some doctors appear to have a nose for disease got me thinking about the significant number of individuals I see in practice who complain of a loss of their sense of smell. As odour detection is an intrinsic part of our sense of taste, individuals who experience a decline in their nasal ability will usually find that their ability to savour and enjoy food has waned, too. Rarely, impaired sense of smell, hyposmia, is the result of damage (eg by trauma or a tumour) to the olfactory nerve that sends smell signals to the brain. However, more often it is related to factors that may respond to a nutritional approach.

One of the chief causes of hyposmia is congestion in the membranes in the nose that contain the smell-sensitive nerve endings. Often such congestion, as well as a tendency to snotty build-up, is related to eating 'mucous-forming' foods. Dairy products such as milk, cheese, yogurt and ice cream are generally the worst offenders, and those prone to nasal stuffiness might benefit from eschewing these for a few days. Should this help clear congestion, the reintroduction of foods, one by one, back into the diet can identify which specific foods are the problem.

Another nutritionally related cause for hyposmia is a deficiency in zinc. Infections are believed to make a drain on the body's stores of zinc, which may help explain why some people find their sense of smell is impaired after a cold or a bout of flu. Those keen to boost zinc levels can find this mineral in oysters, lentils, sunflower seeds and pecan nuts. In addition, I recommend supplementing with 30mg of zinc a day for three or four months. Should this help restore the sense of smell, it is a good idea to continue supplementation with a multivitamin and mineral which contains at least 7mg of zinc each day. My experience is that these natural approaches can be very effective in helping individuals to pick up the scent.

Dear John

I am 32 and sometimes have difficulty swallowing, especially if I am eating when feeling anxious or stressed. Also, I can suffer from severe chest pain after meals. I have had an endoscopy and barium swallow, both of which were 'normal'. Do you know what might be causing my symptoms?
FP

I suspect you are suffering from oesophageal spasm - cramp in the muscles that line the tube that takes food from the back of the throat to the stomach. Because of a tendency for the spasm to come and go, medical tests such as endoscopy or barium swallow (visualisation of the upper part of the gut using a camera or X-ray contrast medium, respectively) often yield nothing unusual. In my experience, oesophageal spasm is related to a deficiency in magnesium, which is essential for normal muscle function - a deficiency increases the risk that the muscle in the oesophagus (or elsewhere in the body) will go into spasm. Nuts are a good source of magnesium, so include them in your diet on a regular basis. In addition, take 350-500mg of magnesium each day.

Nutrition news

There is now a wealth of evidence which suggests that eating an abundance of fruits and vegetables can help to protect the body against cancer. Specific elements in plant-based foods may exert this benefit through a variety of mechanisms, including the de-activation of chemicals or genes involved in the cancer-causing process. Another way food components may help to protect against cancer is by triggering the death of cancerous cells - a process known as apoptosis.

At a recent meeting of the American Association for Cancer Research in America, for example, researchers from the University of Pittsburgh presented the results of a study in which the potential cancer-protective properties of red chilli peppers were assessed. The researchers added capsaicin (the component of chilli peppers that makes them hot) to pancreatic cancer cells in the test tube.

Capsaicin was found to induce apoptosis in pancreatic cancer cells, but left normal pancreatic cells unharmed.

· Dr John Briffa will be away next week

· If you have any issues you would like Dr Briffa to address in his column, please email him on john.briffa@observer.co.uk. Please note that Dr Briffa cannot enter into any correspondence. You can also visit www.drbriffa.com. Before following any recommendations in this column, you should consult your own medical adviser about any medical problems or special health conditions