It is already known that smoking can affect a person's sense of taste, however a new study suggests that it is the ability to taste bitterness that really suffers.

According to French scientists, smoking causes a loss of taste, as well as structural changes to the part of the tongue where the taste buds are found. However until now, it has been unclear whether a person regains their full sense of taste after quitting smoking.

The scientists decided to look into this further. They tested the ability of over 450 hospital workers to recognise the four basic tastes - sweet, sour, salty and bitter. They also assessed how intense the participants found these tastes.

The participants were divided into three groups - smokers, non-smokers and people who had managed to quit the habit.

The study found that the smoking status of each person did not affect their ability to recogniss sweet, sour and salty tastes. However, it did affect their ability to recognise the bitter taste of caffeine.

Usually, this taste can be detected at very low concentrations. However, one in every five current smokers and one in every four previous smokers could not recognise this taste at all.

Just 13% of non-smokers failed to identify the bitter samples they were given.

The scientists suggested that the build-up of tobacco in the body may adversely affect the regeneration of taste buds, resulting in some people's sense of taste still being affected even if they have managed to quit the habit.

Details of these findings are published in the journal, Chemosensory Perception.