British savoury spread Marmite could be illegal in Denmark if it fails to meet safety requirements, officials say.
By law, the Danish authorities must give their approval for food fortified by vitamins or minerals before sale.
Products with such additives need to be assessed for any potential dangers, the Danish Food and Veterinary Administration says.
Denmark has previously banned several popular items, including the drink Ovaltine and some breakfast cereals.
A shop in Copenhagen was recently asked to remove its supplies of Marmite following a phone call from Danish authorities, the owner says.
A spokesman for the Danish Food and Veterinary Administration said: "We have no record of an application for the sale of the product, so we have neither forbidden or accepted it."
The procedural checks needed before a final decision is reached could take up to six months.
If a ban is put in place, outraged fans of the spread in Denmark are threatening a campaign of civil disobedience, the BBC's Europe correspondent Chris Morris says.
Nutritionist Melanie Brown told the BBC she believed a ban on Marmite, which is rich in B-vitamins such as riboflavin and niacin, would be counterproductive.
"Marmite plays such a useful part in many people's diet, and in my practice it's incredibly useful for older people...who are short in vitamin B12.
"It's full of folic acid, and there's lots of evidence that many women, young women of child-bearing age are deficient in folic acid," she said.