Drinking white wine can make teeth more prone to stains, according to research at New York University.
Scientists working with cow teeth discovered that exposure to the acid in white wine makes teeth more likely to be discoloured by substances like coffee and tea.
Dr Mark Wolff said: "Dipping teeth in white wine for one hour is similar to the effect of sipping the wine with dinner.
"The acids in wine create rough spots and grooves that enable chemicals in other beverages that cause staining, such as coffee and tea, to penetrate deeper into the tooth."
Although white wine has not previously been widely associated with tooth staining, red wine has long been regarded as a hazard by wine lovers who are anxious to maintain a white smile. The research confirmed their suspicions.
The experiment was repeated with red varieties and created darker stains in the cow teeth, thanks to the presence of chromagen.
Dr Wolff said wine drinkers should use toothpastes containing whitening agents rather than necessarily cut back on their consumption.