Why does red wine stain your teeth?

You know the feeling: a wonderful evening of red wine, and then you catch your reflection and notice your teeth have turned a shade of purple. Why does this happen, and — more importantly — what can you do about it?

The culprits are anthocyanins, the natural pigments in red grape skins that give red wine its colour. A young red wine can contain 200-500 mg/l of these pigments, with deeply coloured varieties like Malbec and Tannat reaching over 800 mg/l. These molecules are intensely coloured and eager to stick to surfaces.

The staining process works in three steps. First, the wine's acidity (average pH 3.3-3.6) temporarily softens your tooth enamel, making its surface slightly porous. Second, tannins in the wine bind to the proteins in your saliva and to the enamel's natural biofilm, acting like a glue. Third, the anthocyanin pigments latch onto this tannin-protein layer and settle into the microscopic pores.

The good news: red wine stains on teeth are mostly superficial and temporary. Here are some practical tips to minimise them. Drink water between sips — it rinses pigments away and restores your mouth's pH. Eat hard cheese — the casein protein in dairy binds to tannins and creates a protective layer on your enamel. Wait at least 30 minutes before brushing — brushing while your enamel is still softened by acid can do more harm than good.

A fun fact: white wine does not stain your teeth directly, but its higher acidity can soften your enamel and make it more susceptible to staining from other foods you eat afterward — coffee, tomato sauce, berries. So that Chardonnay followed by an espresso might be just as risky as a glass of Malbec.