Wednesday October 22
Loss of Smell, Taste Affect Health
NEW YORK (Reuters) -- Loss of sense of taste and smell can
lead to nutritional and immune problems in older people and put
them at risk for food poisoning, according to a report in The
Journal of the American Medical Association this week.
A review of the scientific literature shows that loss of
these senses is common in the elderly. Deficits in these senses
can be caused by illness, medications, and by the process of
aging itself.
"Many people lose their sense of smell and taste, and all
people lose it to some degree as they age," says the review's
author Dr. Susan S. Schiffman, professor of medical psychology
at Duke University Medical Center in Durham, North Carolina.
"With taste, the loss is modest with just normal aging, but
medications and diseases can play a tremendous role," Schiffman
says. She notes, for example, that medications such as
psychotropic drugs interrupt connections between nerve cells,
to affect the taste and smell centers in the brain.
The researcher also notes that environmental exposure to
chemicals such as insecticides and pesticides can damage the
body's smell receptors and can interfere with the sense of
taste.
"Deficits in taste and smell can not only reduce pleasure
and comfort from food, but they can alter the types and amounts
of food eaten and can actually reduce the levels of key immune
system cells, like T-cells and B-cells," Schiffman says.
Schiffman says her own research demonstrated that taste and
smell also put the elderly at risk for noxious chemicals and
poisonings "since chemosensory cues provide warning signals
about chemical safety."
Deficits in chemosensory cues have other dangers, the
researcher notes. A diminished ability to taste sweet foods can
put elderly people with diabetes at risk for accidentally eating
sugar, thus affecting the control of their diabetes. Loss of
salt perception can cause people with high blood pressure to
inadvertently consume too much salt.
The psychologist's research in elderly nursing home patients
also suggests that flavors and odors may stimulate nerve
pathways leading to the brain's limbic system, which regulates
such diverse functions as mood, productivity, and immunity.
"It is important as you age to make sure that your food
tastes and smells good to you," the researcher says. "Odor and
taste may activate, or stimulate the immune system."
"There are connections between the smell centers in the
brain and the immune system," Schiffman adds. "We found that
T-cell and B-cell levels were increased when patients ate
flavor-enhanced food. And we believe, from further studies, that
the reason for that is stimulation of the limbic system of the
brain improves the immune system."
Schiffman also notes that food could help older people who
have dryness of the mouth from taking certain medications that
can block salivation. "When you have more flavored foods, you
get more salivation, less complaints of dry mouth, and more
bathing of the oral passages with immunoglobulins
(antibodies)," she points out.
In terms of intervention, the researcher suggests that
elderly patients who complain of sensory loss undergo a
four-step evaluation process including a complete medical
history, physical examination, psychophysical testing for
sensory deficits, and, possibly, diagnostic medical imaging.
Schiffman says once the evaluation is complete, the doctor
may suggest adding simulated flavors to foods -- concentrated
essences which, unlike spices, do not irritate the stomach.
"Enhancing food flavors and understanding triggers for
taste and smell can help older patients adjust to the
physiologic changes that occur with age and help maintain
appetite and food enjoyment," the researcher states.
SOURCE: The Journal of the American Medical Association
(1997;278(16):1357-1362)
