Teeth become less white as you get older. This is a natural process which cannot be prevented. It is due to the mineral structure of the teeth, which in time affects the enamel and causes it to discolour. In addition, teeth can be more susceptible to discolouration due to bacteria, food and drinks. Coffee, tea, red wine and tobacco lovers are more likely to get stains on their teeth than people who avoid all products that cause staining. However, you can never 100% prevent tooth discolouration, even if you only drink water, so to speak.