Is dodgy Christmas dinner to blame for my upset stomach?

I went out for a Christmas dinner with friends last week and a day later had really bad stomach cramps and diarrhoea.

- DR ROSEMARY LEONARD

We all ate the same food — smoked salmon, turkey with all the trimmings, mince pies, but I was the only one who was ill. So should I complain to the restaurant?It's common to assume that when you have a stomach upset, something you ate recently is to blame, but often it's something you ate several days previously that is the culprit.

The most common cause of food poisoning in the UK is campylobacter bacteria, which cause diarrhoea that may be bloody, as well as abdominal pain, nausea and feeling tired and unwell. Symptoms usually start between two and five days after eating contaminated food, but it may be up to 11 days later.

Though campylobacter can be found in red meat or shellfish, the most common culprit is undercooked poultry, and that means that an undercooked turkey on Christmas Day may be to blame for someone being ill at the new year, rather than Boxing Day.

Another common infective cause of diarrhoea is E.coli, found in raw meat and fruit and veg that have not been washed, and though symptoms usually start three to four days after eating the culprit food, there may be a delay of up to two weeks.

However, eating bacteria that trigger vomiting as well as diarrhoea usually causes symptoms more quickly.

Salmonella, in undercooked poultry and meat, as well as eggs and unpasteurised dairy products, causes symptoms from six hours to 48 hours afterwards, while bacillus cereus, found in cooked rice that has been left at room temperature, can cause vomiting within an hour.