Enamel is the hardest tissue the body makes, and it is also the only one that never regenerates. What wears it down is not usually sugar alone but acid, and acid turns up in places most people consider harmless.

Citrus, vinegar and sparkling water

Lemon in hot water first thing, a daily vinegar dressing, flavoured sparkling water at the desk. Each one drops the pH in the mouth for around twenty minutes. It is the repetition rather than any single serving that does the damage.

Dried fruit and sticky snacks

Raisins and dried apricots are concentrated sugar in a form that presses into the grooves of the molars and stays there. If you eat them, follow with water or a piece of cheese, which helps neutralise the acid that follows.

Do not brush immediately

Softened enamel brushes away. After anything acidic, rinse with plain water and wait half an hour before brushing. It feels counterintuitive, and it is the single easiest habit on this list to fix.