Change in taste, especially loss of taste, is very common in elderly people, and caused by a variety of things. Like most of our senses, the sense of taste tends to decline with age as the taste buds degenerate. Then problems which would cause a bit of a loss of taste in younger people can wipe out what little remains in an older person.

This loss (or distortion) of taste and smell can then take away someone's appetite so that they're less interested in eating. Older people often tend to have a poorer appetite anyway (many elderly people exist on tea, toast, biscuits and other snacks) and so quickly lose weight. This may explain your grandfather's weight loss but there may be other explanations too such as some of the illnesses listed below which can cause a change in taste.

Loss of smell may be the problem

Very often, the person actually loses their sense of smell - and this is what causes a change in taste (smell is a major contributor to the sense of taste). Smell is disrupted by conditions which affect the lining of the nose, such as the common cold or chronic rhinitis. More rarely, it's affected by nerve problems, ranging from damage to nerves in the nose, to damage to areas of the brain controlling smell (such as from a stroke).

Loss of smell usually causes loss of taste rather than a change of taste, or the sensation of bitterness that your father is experiencing.

Oral problems

Perhaps the most common cause of taste problems, especially in the elderly, is problems in the mouth - with teeth or saliva.

Any condition which results in a dry mouth can cause problems because saliva is essential for taste. Chemicals in food or drink dissolve in saliva and this bathes the taste buds. In a dry mouth, the chemicals never reach the taste buds.

Anything which causes inflammation in the mouth can damage the taste buds. Ill-fitting dentures or teeth and gums full of decay are some of the major culprits. Smoking can also destroy taste.

Rare causes of taste problems

More rarely there may be:

• damage to the nerves between face and brain
• stroke
• brain tumours
• tumours elsewhere in the body
• liver disease
• extreme vitamin deficiencies
• some medicines and drugs can cause changes in taste
• depression and other psychological problems can cause alteration in taste
• heavy metal poisoning (a change in taste, and particularly a bitter taste, is one of the perennial clues in murder mysteries but extremely rare these days)

Ensure your grandfather has seen his doctor to rule out any medical causes, and a dentist to check his mouth and gums. Then it's a matter of trial and error in the kitchen to find ways to tempt his palate. Alternatively, you might want to explore complementary therapies such as acupuncture.

This article was last medically reviewed by Dr Trisha Macnair in August 2008