Taste helps all of us recognize when food is good or bad. When an elderly person loses taste, it can cause a loss of appetite, weight loss, poor nutrition, weakened immunity, and even death.
Normal taste occurs when molecules released by chewing or the digestion of food stimulate special sensory cells in the mouth and throat. These taste cells, or gustatory cells, send messages through three specialized taste nerves to the brain, where specific tastes are identified. Damage to these nerves following head injury can lead to taste loss.
The taste cells are clustered within the taste buds of the tongue and roof of the mouth, and along the lining of the throat. Many of the small bumps that can be seen on the tip of the tongue contain taste buds. At birth, we have about 10,000 taste buds scattered on the back, side, and tip of the tongue.
After age 50, we may start to lose taste buds. We can experience five basic taste sensations: sweet, sour, bitter, salty, and umami, or savory. Umami was discovered by a Japanese scientist in the early part of the twentieth century. It is the taste of glutamate, a building block of protein found in chicken broth, meat stock, and some cheeses. Umami is the taste associated with MSG (monosodium glutamate) that is often added to foods as a flavor enhancer.
The five taste qualities combine with other oral sensations, such as texture, spiciness, temperature, and aroma to produce what is commonly referred to as flavor. It is flavor that lets us know whether we are eating an apple or a pear. Many people are surprised to learn that we recognize flavors largely through our sense of smell. Try holding your nose while eating chocolate. You will be able to distinguish between its sweetness and bitterness, but you can't identify the chocolate flavor. That's because the distinguishing characteristic of chocolate is largely identified by our sense of smell as aromas are released during chewing.
Food flavor is affected by a head cold or nasal congestion because the aroma of food does not reach the sensory cells that detect odors. A distorted sense of taste can be a serious risk factor for heart disease, diabetes, stroke, and other illnesses that require sticking to a specific diet. When taste is impaired, a person may change his or her eating habits. Some people may eat too little and lose weight, while others may eat too much and gain weight.
Many older people believe that there is nothing they can do about their weakened sense of taste. Depending on the cause of your problem, your doctor may be able to suggest ways to regain your sense of taste or to cope with the loss of taste. In many cases, the loss of taste turns out to be a loss of smell. If you think you have a problem with your sense of taste, see your doctor.
Causes and Prevention of Taste Loss in Elderly Parents
Problems with taste are caused by anything that interrupts the transfer of taste sensations to the brain, or by conditions that affect the way the brain interprets the sensation of taste. The most common causes of taste disorders are:
- Head injuries
- Dental problems
- Radiation therapy for head and neck cancers
- Mouth dryness
- Heavy smoking
- Vitamin deficiencies
- Bell's palsy, and Sjogren's syndrome
- Taking medications. Some antibiotics and blood pressure pills can cause a bad taste in the mouth or a loss of taste. Talk to your doctor about it.
- Gum disease. Dentures and inflammation or infections in the mouth caused by taking several medications. This causes dry mouth, which can make swallowing and digestion difficult and increase dental problems.
One type of taste disorder is characterized by a persistent bad taste in the mouth, such as a bitter or salty taste. This is called dysgeusia and it occurs in older people, usually because of medications or oral health problems.
The medicines that most frequently cause dysgeusias are drugs to lower cholesterol, antibiotics, blood pressure pills, medications to lower anxiety, and antidepressants. Smokers often report an improved sense of taste after quitting. Sometimes exposure to certain chemicals, such as insecticides and solvents, can impair taste.
Avoid contact with these substances, and if your aging parent does come in contact with them and experience a problem, see your doctor. You can help prevent problems with taste caused by respiratory infections by washing your mom or dad's hands frequently, especially during the winter months. If your elderly parent's taste disorder is made worse by allergies, avoid allergens, such as ragweed, grasses, and pet dander. Also, have your elderly mother or father get a flu shot every year to prevent influenza and other serious respiratory conditions that can result from the flu.
Symptoms and Diagnosis of Taste Loss
There are several types of taste disorders depending on how the sense of taste is affected. People who have taste disorders usually lose their ability to taste or can no longer perceive taste in the same way.
The most common taste complaint is "phantom taste perception" -- tasting something when nothing is in the mouth. Some people have hypogeusia, or the reduced ability to taste. This disorder is usually temporary.
True taste disorders are rare. Most changes in the perception of food flavor result from the loss of smell. Other people can't detect taste at all, which is called ageusia. This type of taste disorder can be caused by head trauma; some surgical procedures, such as middle ear surgery or extraction of the third molar; radiation therapy; and viral infections.
More often, people with taste disorders experience a specific ageusia of one or more of the five taste categories: sweet, sour, bitter, salty, and umami, or savory. Your doctor may refer you to an otolaryngologist, a specialist in diseases of the ear, nose, and throat. After conducting a complete medical history and physical examination, your doctor may run special tests to find out what type of taste disorder you have and how serious it is.
Some tests are designed to measure the lowest concentration of a substance that a person can detect or recognize. Your doctor may ask your elderly mother or father to compare the tastes of different substances or to note how the intensity of a taste grows when a substances concentration is increased.
Scientists have developed taste tests in which the patient responds to different concentrations of a substance. This may involve a simple "sip, spit, and rinse" test or the application of a substance directly to your tongue using an eye dropper. By using these tests, your doctor can determine if your aging mom or dad has a true taste disorder and what type it is. If your doctor suspects that nerves in your parent's mouth or head may be affected, he or she may order an X-ray, usually a CAT scan, to look further into the head and neck area.
Although there is no treatment for any gradual loss of taste that occurs with aging, relief from taste disorders is possible for many older people.
Depending on the cause of your elder's problem with taste, the doctor may be able to treat it or suggest ways to cope with it.
Scientists are studying how loss of taste occurs so that treatments can be developed.
The National Institute on Aging (NIA), one of the 27 Institutes and Centers of the National Institute of Health (NIH) leads a broad scientific effort to understand the nature of aging and to extend the healthy, active years of life. In 1974, Congress granted authority to form NIA to provide leadership in aging research, training, health information dissemination, and other programs relevant to aging and older people.