People who suffer from a food intolerance and are affected by discomfort such as nausea and bloating should keep a food diary, according to Food Intolerance Awareness.

Muriel Simmons, chief executive of the Allergy UK department, explains that while keeping such a record may be a painstaking process, it is the only way to effectively find out what is triggering the symptoms.

She states that the only way to treat a food intolerance is to exclude the fare which make an individual ill from meals.

Ms Simmons recommends that if a particular type of food is identified as being a trigger, it should be cut from a sufferer's diet for a month to see if it improves health.

"If your symptoms do improve, try gradually re-introducing it in small amounts and in rotation," she concludes.

According to Allergy UK, 45 per cent of the population suffer from a food intolerance.