The unexpected impact of taste and smell

Often overlooked by more 'attractive' senses such as sight or touch, taste and smell are more complex than we think. They also have a surprisingly large impact on people's behavior, awareness and general health status.

According to a new study, the sense of smell often provides clues to some of the mysteries of people with Parkinson's disease more than dementia, while genetic differences in taste may hold the secret to predicting things. We eat, how well our metabolite system works, even if we know whether we are overweight or not.

Experts say that taste and smell work together in ways that we cannot recognize, thereby creating the basic feelings for our daily lives.

Tom Finger, a professor at Colorado Medical University, Denver, and president of the 2008 Sensory and Visual International Symposium held last month in San Francisco, said: combination of taste and smell. If you cover your nose and chew the marshmallow, you definitely can't feel the taste. But if you stop covering your nose while chewing, you will suddenly notice the apple or watermelon candy. '

That's because when you chew, the air that passes through the nose carries the scent of food with it. Without the combination of taste and smell, you will not be able to get the complex flavors. You will be limited to some basic taste sensations that the tongue receives chemically like salty, sour, sweet, bitter and umami tastes - this is a delicious taste related to MSG additives (or powder). sweet).

Because of this connection, if you lose your sense of smell, it will cause great losses . Food will no longer taste good, people will lose a lot of emotional relationships related to scent. For example, studies have shown that people, especially women, can identify their partner's specific scent. Because scents are often more special than shapes or other things that can be seen, scent is always linked to our memories of places or events.

Richard Doty, a professor and director of the Center for Odor and Taste at the University of Pennsylvania School of Medicine, said: 'Scent is a strange thing that we always remember. A scent similar to the scent coming out of a room where your grandmother keeps food may relate to your memories of that room faster than looking at the general image of the same room. '

Fragrance and memory mixed together

Doty also thinks that the sense of smell and memory can link together in a more confusing way. Loss of smell is one of the early symptoms of degenerative neurological diseases such as Parkinson's disease and Alzheimer's dementia. In fact, he suggests that studies have demonstrated a close relationship between diminished sense of smell and the likelihood of people developing these diseases later.

'Studies have investigated the sense of smell in people without symptoms of Parkinson's disease and followed 10% of the top participants as well as 10% of the participants at the bottom of the list for many years. All people diagnosed with Parkinson's disease in the second half of life are in the group with olfactory disorders when they are young. '

Why are things that seem disjointed linked to each other? Doty said it is possible that a significant number of Alzheimer's and Parkinson's cases are caused by the environment. At that time, the nose can act as an entry point for agents prions, viruses or toxins that enter the brain and destroy the brain.

The combination of taste and smell helps us to feel more complex flavors.(Photo: dkimages)

Although this hypothesis has not been proven, there is a lot of indirect evidence that the nose and olfactory system are related to these diseases. Doty lists some evidence on the January 29 article in Annals of Neurobiology. He said that if the hypothesis proved correct, we could study more effective ways to prevent disease, including pharmaceuticals or filters that prevent intruders from reaching the brain. set through the nose.

Genetic taste

Meanwhile, other studies published at the San Francisco symposium demonstrate some of the important connections between the genetically programmed people to feel and how we eat. . These relationships may explain some of the genetic factors of obesity.

An example is GLP-1, a hormone that has long been known to be produced by the stomach to control pancreatic insulin production. In the July issue of the Journal of Neurochemstry, Steven Munger - assistant professor of anatomy and neurobiology at the University of Maryland Medical School - presented evidence that some tongue cells also have production of GLP-1. Munger's team also demonstrated that GLP-1 helps the tongue 'communicate' with the brain, especially when there is a sweet taste on the tongue. When they created mice lacking in GLP-1 receptors, they lost most of their ability to sense the taste of sweets.

According to Munger, GLP-1 plays a role in human food choices. Some people are better able to produce or identify GLP-1 than others. More importantly, research has shown that there is a strong relationship between taste and metabolism.

'GLP-1 is not the only hormone that works in the taste system. Leptin in fat also plays a role. GLP-1 and leptin seem to work in opposition. One is the receiving body and the other is the lower receiving body. The result is a proper control of taste-related metabolism. '

Powerful impact

Another compound even plays a bigger role with your food choices: PROP - a chemical indicator for the ability to sense certain bitter tastes. About 70% of people can feel PROP, according to Beverly Tepper, Rutgers University professor of food science, but bitterness is not the only one that has an impact.

'Food tasting experts often find some bitter compounds more bitter than normal people. They feel sweeter like sweeter, hot food is also hotter. They also feel the fat or some of the stronger fats. Ordinary people also taste these but with lower intensity. '

She said people who are not food tasting experts tend to look for foods of a quality that they do not understand as well as being hotter, sweeter, and fatter. 'We have evidence that normal people consume a lot of fat supplements, salads, buttermilk and margarine. We even saw in some studies that people who are not food tasting specialists consume more calories. '

In the 2008 Annual Review of Nutrition - a book published in August, Tepper pointed out that PROP sensitivity can affect each person's diet. The next step in her research is to find out whether it is possible and how a person's knowledge of a person's PROP sensory character is used to help them develop a more personalized diet plan.

She said: 'I would like to find appropriate evidence that we can present to those who want to relieve the sympathy as well as about the difference between tasting experts and ordinary people. For example, we are often asked to reduce the amount of fat consumed but this can be very difficult for amateurs. So perhaps the published food book may encourage them to make up for the lack of sensation from a low-fat diet. Maybe by adding non-calorie flavor enhancers like vinegar or mustard.