Food expert Linda Planton has studied for the last seven years the effect of different food on different people.

A bumper-sized bar of chocolate may be your chosen reward at the end of a hard day, but could that energy-boosting treat be to blame for lethargy striking an hour later?

Could a healthy bowl of strawberries be the trigger for a bout of hives? And could old wives tales be true about cheese sandwiches causing insomnia?

Sensitivity to foods is on the increase, provoking not full blown allergies but a range of uncomfortable symptoms which most people attribute to " going down with something" rather than the real cause - something they ate.

Food expert Linda Planton sees up to 40 people a week who are trying to pin down a reason for their general feeling of being unwell.

She is trained as an orthodox nutritionist, but for the last seven years she has made increasing use of a testing machine which uses the power of the body's own electrical energy.

The Vegatest machine, developed 20 years ago in Germany, measures resistance to each foodstuff as it is introduced into a low voltage circuit running painlessly through the body.

The client holds an electrode on one hand, Linda holds a stylus against an acupuncture point on the other hand, and the food in diluted form is placed in the Vegatest. If the client's system doesn't like the food a low reading is registered on the machine.

Linda is convinced the quick and simple system can't be bettered.

"Orthodox medical practitioners accept this method - one local doctor even refers patients to me," she said.

"I can run through 67 foods in less than 30 minutes and give you a clear idea of which might be causing you problems and should be eliminated from your diet.

"To carry out blood tests for all these substances would be incredibly expensive, and take a long time."

Linda says she gets busier every year and attributes the increase to people suffering more stress and eating more time-saving processed foods.

"Stress affects the way you absorb nutrients, and processed food - especially microwaved - is nutrient-deficient to start with. Most people I test are lacking several important trace elements," said Linda.

Once the tests have been recorded she can help clients reorganise their diets for better health.

"If a person has a marked sensitivity to a food it is best to cut it out completely for four weeks and give the body a rest," said Linda.

"Then the food can gradually be reintroduced to see if the sensitivity has gone. It is often just a question of giving an inflamed digestive tract time to heal."

Linda Planton holds testing clinics all over Hampshire, usually at Holland and Barrett health food shops. Ring her on 01202 54 87 69 to check her timetable.