Most people understand that as we age, the way in which we
experience our world through our senses of sight, hearing, touch, taste, and
smell changes as those senses deteriorate over time. As our visual acuity
diminishes, we wear corrective lenses; with auditory loss, we wear hearing
aids. However, the least accepted and least understood deprivations are those
of taste and smell, the two senses that primarily control the body’s ability to
experience food. Disorders of taste and smell are viewed as affecting the
“lower” senses—those involved with sensual and emotional life—rather than the
“higher” senses that serve the intellect.
The taste and smell of food have a major effect on levels of
food intake and the maintenance of good nutrition. Losses and distortions in
these chemosensory mechanisms contribute to a significant degree to anorexia in
the elderly. Taste and smell are considered chemical senses because molecules
that contact receptors in the mouth, throat, and nasal cavity stimulate them.
The sense of taste is mediated by taste buds located on the dorsal surface of
the tongue and on the epiglottis, the larynx, and the first third of the
esophagus. Olfactory receptors are bipolar neurons located in the upper portion
of the nasal cavity that project into the limbic system of the brain. The
limbic system also processes information associated with emotions, so there is,
in fact, a medical explanation for the emotional response we have to food. The
olfactory bulb shows considerable degenerative changes during aging, and
cross-sections of the bulb often look “moth-eaten” owing to losses in the
number of cell bodies of neurons. Those losses are especially profound in
patients with Alzheimer’s disease.
Because of reduced function in these key chemosensory
systems, the natural biochemical responses designed to break down food as it
enters the body are consequently also less active. When the body smells,
tastes, or simply sees appetizing food, a number of biochemical responses are
set in motion to aid subsequent digestion. For example, saliva builds up in the
mouth, gastrointestinal juices are released into the stomach, plasma insulin is
released into the bloodstream, and the pancreatic system is engaged. All these
responses have the combined effect of aiding absorption of food and promoting
overall nutrition. As the aging process affects the body’s internal response to
food, seniors do not enjoy food as much or absorb it as well, and as a result
they can become vulnerable to malnutrition, which can contribute further to
health problems.
Taste and smell decrements arise not only from the normal
aging process, but also from certain disease states, pharmacological and
surgical interventions, the effects of radiation, and environmental exposure.
Similar medical conditions and drugs affect the sense of smell. For example,
most people have experienced the metallic taste of orange juice after brushing
their teeth; the chemical in toothpaste responsible for this effect is sodium
lauryl sulfate, which is also used to help fat-soluble drugs dissolve. Most
elderly persons take their medications with their meals to offset the
potentially harmful effects of the drugs on the stomach lining, which in turn
affects their ability to taste and smell their food. Their senses are inhibited
by these drugs, as is their digestive system, and this effect can at times
induce a negative reaction and in severe cases lead to malnutrition.
Many medications commonly prescribed are recommended to be
taken with food. Often people will take their medications before they eat,
especially when dinner plans call for a night out to a restaurant. By the time
their meals actually arrive at the table 60 minutes or more could have passed
since they consumed the medication prior to leaving home, giving the medication
taken on an empty stomach ample time to be absorbed into the bloodstream and
the opportunity to adversely affect their ability to taste and smell their
food. Simply advising people to take their medications after they eat rather
than before can have a profound effect on their overall dining satisfaction. In
fact, at one senior living community, after the seniors were educated about
this concept, senior satisfaction in food and beverage service increased by 10
percent over the previous survey, while perceptions of all other conditions
remained constant[i].
Measurements of taste and smell dysfunction in adults reveal
a progressive decline with age. Those losses tend to begin around 60 years of
age and become more severe in persons over 70 years of age. In most retirement
communities, the chef and cooking staff have an ability to taste and smell that
is more than twice as acute as that of the people for whom they are cooking. In
one study, persons between the ages of 20 and 70 had approximately 206 taste
buds each. This number was reduced to 88 taste buds for persons between the
ages of 74 and 88 years. The average age of seniors in retirement
communities today is about 82 years. Therefore even the best-qualified chefs
working with the freshest natural ingredients are working at a considerable
disadvantage, and they will express their frustration in trying to address this
problem using conventional methods. Seniors may inadvertently harm themselves
by trying to amplify the flavors of their food by using too much salt at the
table, or by eating too much dessert because they can still enjoy the sweet
taste of many of these offerings. Compensating in these ways, however, only
leads to nutritional imbalances and could be in direct conflict with
doctor-prescribed dietary guidelines.
Recent studies suggest that the amplification of foods and
beverages with naturally produced flavors can increase preference ratings as
well as subsequent intake and absorption in elderly persons with known
chemosensory losses. These commercially produced flavor enhancers, which are
inexpensive (adding less than a penny to the per-meal cost), are made by
reducing food such as chicken and capturing and concentrating natural flavor
and odor molecules. The concentrate can then be attached to a “carrier” (such
as water, oil, or flour) and added to the food. This added flavor contains no
fat, salt, or other harmful products traditionally associated with flavor
enhancement.
Flavor-amplified foods not only are preferred from a sensory
standpoint, but also can influence the body’s natural biochemical response to
food, actually promoting better absorption and, as a result, improving the
immune status of elderly persons. In a study by Schiffman and Warwick, elderly
persons were offered regular food for three weeks, then flavor-enhanced
versions of the same food[ii].
Blood samples were taken before and after the use of the flavor enhancement.
They showed an increase in levels of T and B cells (white blood cells), the
body’s natural defense agents against disease and injury. Schiffman’s
research confirms that as the body’s biochemical absorption of food improves,
so do nutrition and immune status. This research suggests that the addition to
recipes of natural flavors that increase the perceived flavor intensity would
improve satisfaction with the food and compensate for chemosensory losses due
to normal aging, diseases, and prescription drugs. It can be argued that the
use of flavor enhancements can actually promote better health as well as
improve culinary satisfaction.
The increased preference for flavor-enhanced food is
extraordinary. In fact, many manufacturers of convenience products, such as Stouffers
and Tyson, now list natural flavors among their ingredients. When a convenience
product and its scratch-made counterpart are served, the convenience product is
often better received than the homemade one. This is simply because the
commercial product is higher in flavor than the homemade product as a result of
added natural flavor. Certainly natural products are important and should
represent the primary ingredient source. The addition of fresh herbs and spices
and pre-treating with marinades should not be abandoned. We walk a fine line,
however: for if too many herbs and spices are added, the seasoning then
overpowers the main ingredients. Often seniors’ delicate digestive systems
become agitated when aromatic herbs and spices are not used in moderation.
Research has confirmed an improved immune status as measured
by the total level of blood lymphocytes, which help to fight diseases inherent
in the elderly population. In addition, seniors feel better about their dining
experience, and opioid (endorphin) levels increase as seniors’ ability to sense
their food improves. It has actually been proven that seniors become physically
stronger as well. With flavor enhancement, seniors are less interested in fatty
foods and in adding salt to their entrees, and thus they are better able to
adhere to their doctor-prescribed dietary guidelines.
[i] Benjamin W. Pearce, Reactivating
Appetite, Eldercare Advisor Press, Amazon Kindle eBook, Amazon Digital
Services (2014).
[ii] S. S. Schiffman and Z. S. Warwick, "Effects of Flavor
Enhancement of Foods for the Elderly on Nutritional Status: Food Intake,
Biochemical Indices, and Anthropometric Measures," Physiology and Behavior 53 (1992): 395-402.
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