Many would think that members of the British Royal Family can get whatever they want, whenever they want, but there are certain foods that they're actually banned from eating when out and about.

One downside to being a royal is that you can't eat particular foods, according to The Sun, and they are advised against ordering shellfish when they eat out due to risks of food poisoning. We all know someone who's suffered the consequences of dodgy oysters.

But it isn't just shellfish that is rejected, with Kate and co being advised to steer clear of meat cooked rare and tap water when pursuing royal engagements overseas.

Eating undercooked meat puts you at risk of ingesting E.coli – which can cause symptoms of diarrhoea, vomiting and stomach cramps. Salmonella, Listeria and other food-borne illnesses can be contracted from consuming raw meat.

Precautions are in place to hopefully avoid any of the royals getting a bug which may hinder their busy schedules – and the Duke and Duchess of Cambridge need to listen to any advice they can with two children on their hands and an increased work load now that Prince Philip has retired and the Queen is slowing down.

The Queen is said to always observe the food rules, while some of the younger royal members have been known to eat any grub they want.

Kate Middleton, 35, has been known to feast on the high-protein, low-carb Dukan Diet but also ate a lot of fruit and oats during her pregnancies. The Queen is said to thrive on a balanced diet of lots of fruit and vegetables and enjoys the occasional treat of dark chocolate and a swig of Gewürztraminer.

Her former chef Darren McGrady previously said: "The Queen is very disciplined. It is partly that and partly her genes. That's what keeps her so slim – cutting out those carbs when she is not entertaining."

Prince Philip Duke of Edinburgh
19 November 2007:The Queen and the Duke of Edinburgh walk at Broadlands in an official photo taken to mark their diamond wedding anniversary Fiona Hanson