A royal tradition will force Meghan Markle to change her diet before her wedding to Prince Harry -- here are 8 things a food-poisoning expert says to avoid

Meghan Markle is preparing to follow in the footsteps of Queen Elizabeth II as the royal wedding date nears — and that includes culinary traditions.

A "weird rule prevents the Queen and other royals from eating foods like mussels and rare steak when dining out," The Sun reported.

The Sun added: "They're advised to steer clear of foods which could cause food poisoning, like shellfish, rare meat and tap water when they're abroad."

It's a sensible tradition — no one wants to be forced to alert the public that they need to miss a royal function because they have contracted food poisoning from slurping down raw oysters. According to The Sun, Queen Elizabeth follows the tradition closely, while other members of the royal family are more lenient.

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Food-poisoning attorney Bill Marler follows a similarly strict diet, according to past conversations with Business Insider and an article by Health Insider from BottomLine. Marler has won more than $600 million for clients in foodborne-illness cases and has become convinced that some foods aren't worth the risk.

Here are the foods that Marler says anyone trying to avoid food poisoning should stay away from.