At a time when most people have probably polished off their holiday leftovers, Belgium’s food agency has issued a surprising seasonal health warning: don’t eat your Christmas tree.

The message on Tuesday came after the city of Ghent, an environmentalist stronghold in the country’s northern Flanders region, raised eyebrows by posting tips for recycling the conifers on the dinner table.

Pointing with enthusiasm to examples from Scandinavia, the town website suggested needles could be stripped, blanched and dried – for use in making flavoured butter, for instance.

Asked what they thought of the idea, the reply from Belgium’s federal agency for food chain security, AFSCA, was a resounding “No.”

“Christmas trees are not destined to enter the food chain,” it said in a statement.

“There is no way to ensure that eating Christmas trees is safe – either for people or animals,” it said, citing the likely presence of pesticides on most trees cultivated for the season.

“What’s more, there is no easy way for consumers to tell if Christmas trees have been treated with flame retardant – and not knowing that could have serious, even fatal consequences,” the agency warned.

“In short, there are many reasons not to promote nor encourage the re-use of Christmas trees in the food chain,” it said.

Seemingly taking the warning on board, the city tweaked its post – changing its headline from “Eat your Christmas tree” to read instead: “Scandinavians eat their Christmas trees.”