Posted by: Indonesian Children | November 26, 2009

Food Aversions and the Gut/Brain Connection

Food aversions are far more common, far more diverse both within and across cultures, and far stronger than is often realized. Examination of the characteristics and origins of food aversions can help to illustrate the many contributions of genes and environment to behavior. Further, an understanding of food aversions can be useful in understanding, as well as treating, many eating and drinking disorders.

Classification of Food Aversions

Food aversions have been classified into four types: foods that are rejected because they are dangerous, inappropriate, disgusting, or distasteful. We consider foods to be dangerous, and therefore do not eat these foods, if eating them has previously resulted in physical harm, or if eating these foods is reputed to cause physical harm. However, a dangerous food, such as poisonous mushrooms, would be eaten by someone if there were some medication to prevent any illness from occurring.

Inappropriate foods are items that we consider not to be food. An example of an inappropriate food would be Kentucky bluegrass. Although deer and other herbivores might eat this grass, we would consider it inappropriate for humans to do so. Similarly, there may be an item, such as a particular kind of berry, that is considered to be a food by one culture but not by another.

There are several reasons why someone might treat an item as an inappropriate food. One involves the taste of the item. From birth, humans find certain tastes, notably the taste of bitter, to be aversive, and therefore may not consider items with those tastes to be appropriate foods. For example, many wild plants taste extremely bitter. Given that poisonous plants are often bitter, scientists believe that humans who avoided bitter tastes were more likely to survive and therefore humans evolved to have an innate aversion to bitter tastes. Direct experience with an item may also contribute to its classification as an inappropriate food; attempts to chew some wild plants can be fruitless. Finally, someone may consider an item to be an inappropriate food because of information passed on by someone else. For example, caregivers may tell children that grass is not food.

Disgusting foods are those that most of us would not want in our meals or stomachs no matter how the foods were disguised and no matter how small the amount. Some examples of items classified as disgusting foods are urine and feces. Foods can become disgusting because of someone’s having observed others’ reactions to these foods, because of contact of a previously nondisgusting food with something considered disgusting, or because a food looks similar to something disgusting. Thus, because most American children learn from others that insects are disgusting foods, we consider a glass of milk that used to have a cockroach in it to be disgusting, and we find fudge that looks similar to feces to be disgusting. Similarly, cultural beliefs can result in certain foods being considered disgusting. For example, many vegetarians consider meat to be disgusting, and Jews who keep kosher may find meal combinations of meat and dairy products to be disgusting.

Probably the most studied is the fourth and final category: distasteful foods. These are foods that most of us would not mind eating if the taste of the food were covered up by another taste, or if we only found out that we had eaten it after we had finished eating. An example is warm milk. Once again, an innate dislike of certain tastes can contribute to food aversions of this sort. However, many members of the distasteful food category are illness-induced food aversions (also known as taste aversions). Humans and many other species exhibit illnessinduced food aversions when they eat something, become ill, and then do not want to eat that food again. This is an extremely powerful type of learning. Study of the acquisition of illness-induced food aversions has proved extremely important to the development of general learning theory, and has resulted in a number of different applications outside of the laboratory. Therefore, the following sections discuss illness-induced food aversion learning in some detail.

Taste Aversion Learning: Basic Observations

Prior to scientists’ conducting any investigations of taste aversion learning, farmers were aware of this phenomenon, which they called bait shyness. The farmers found that it was difficult to kill rats by putting out poisoned bait. The rats would take only small samples of any new food, in this case the bait, and if they then became ill, they would subsequently avoid the bait.

Laboratory experiments on taste aversion learning began in the 1950s. Researchers noticed that rats eat less after being irradiated. Apparently irradiation makes rats gastrointestinally ill and they associate the illness with food, resulting in a taste aversion to the food.

In 1966 John Garcia and Robert A. Koelling used a taste aversion paradigm to show learning theorists that it is easier to learn some associations than others. In their experiment, rats more easily learned to avoid licking flavored water when that licking was followed by illness than by shock, and they more easily learned to avoid licking water accompanied by clicks and light flashes when that licking was followed by shock than by illness. Garcia and Koelling concluded that it is easier for rats to associate tastes with illness and audiovisual events with shock than vice versa. It was due to results such as these that this type of learning was labeled taste aversion learning.

Odors may also play an important role in food aversions linked to illness, yet the term “taste aversion learning” has persisted. The fact that tastes and odors are more easily associated with illness than with other sorts of events helps us to survive. The presence of a poison is more likely to be indicated by a particular odor or taste than by a particular appearance or sound.

Subsequent experiments found that taste aversion learning has some other special properties that may help animals to survive. For example, taste aversions can be acquired with up to twenty-four hours between consumption of the food and illness. This is advantageous because it may take hours before a poison will result in illness. In addition, in taste aversion learning, the taste actually seems to come to taste bad. This also helps animals to survive because a poison should be avoided no matter under what circumstances it is encountered. Finally, taste aversions are more likely to form to novel foods, and often form after just one pairing of a taste with illness. These characteristics help to ensure that, as much as possible, animals learn quickly to avoid new poisonous foods. Animals appear to have evolved so that they easily acquire long-lasting aversions to cues associated with poisonous foods.

Taste aversion learning has been studied in a great many species, including humans. Surveys have found that most college students report having acquired at least one taste aversion. In general these aversions are strong and have persisted a long time. Laboratory experiments have shown that taste aversions are acquired similarly across species.

Applications of Taste Aversion Learning

Research on taste aversion learning can help us to understand, and possibly modify, many food aversions and preferences. For example, taste aversion learning may cause what are termed specific hungers. These are preferences for specific foods containing a nutrient, such as thiamine or sodium, in which an animal’s diet has been deficient. Animals may feel ill when deficient in these nutrients, and thus form taste aversions to their usual foods. New foods, or foods associated with recovery from the illness, are therefore preferred.

In a very different application, taste aversion learning has been used for wildlife management—to prevent coyotes from attacking sheep on ranches in the western part of the United States. Many ranchers choose simply to kill the coyotes. However, coyotes are a valuable part of the ecosystem (for example, by decreasing the rabbit population). Researchers reasoned that, if they could train the coyotes to avoid sheep but not rabbits, this would preserve the ecosystem. They therefore placed lamb bait laced with an illness-inducing drug on the range in areas frequented by coyotes. The coyotes appeared to acquire an aversion to eating or even approaching sheep. In fact, after aversion training, coyotes behave submissively toward sheep, running the other way when a sheep approaches.

Taste aversion learning has also been helpful in understanding the life-threatening anorexia that can accompany cancer. Some cancer treatments, such as radiation and chemotherapy, can cause gastrointestinal illness. When this illness is paired with food consumption, taste aversions can result. Ilene L. Bernstein and Mary M. Webster gave child and adult patients a novel-tasting ice cream prior to their chemotherapy and the patients acquired an aversion to that ice cream. These findings and others have resulted in the development of the “scapegoat technique.” This technique involves giving cancer patients a novel food along with some familiar food just prior to their chemotherapy. The patient forms an aversion to the novel food and not to the familiar, usual food.

Although it might seem that taste aversion learning could be useful in decreasing overeating, it is not employed for this purpose. Taste aversions form to specific foods, and it is too easy for a patient to switch to overeating a different food once an aversion has been acquired to a previously overconsumed food.

In contrast, taste aversion learning has been successfully employed in treating alcohol abuse, although the pairing of alcohol and illness must be done carefully in order for strong taste aversions to develop. In addition, it is necessary for illness to be paired with a variety of alcoholic beverages in order to ensure that an alcoholic does not switch to new alcoholic beverages following aversion training.

Conclusion

There are a great many different types of food aversions in humans and other animals. Some of these aversions help animals to survive, and others can be extremely debilitating. Continuing research will help to maximize the positive effects of these aversions, and minimize their negative effects.

Martin E. P. Seligman (president of the American Psychological Association in 1998) has described how, in 1972, he ate sauce béarnaise on steak and then became ill with what was definitely stomach flu (his colleague at work who had not eaten the steak came down with the same affliction, and his wife who had eaten the steak did not). Yet, even though he was absolutely convinced that the sauce béarnaise did not cause his illness, Seligman acquired an aversion to it. *

Some children and pregnant women repeatedly consume nonnutritive substances such as paint, plaster, and dirt. Because such food cravings are most likely to appear in people who need a lot of nutrients, it has been proposed that these cravings are the result of specific hungers for minerals such as iron.

GUT-BRAIN Connection to eating problems in children:

Feeding problems: it is a no brainer that these children have feeding problems and gut digestion problems, think about the connection they have to food…not a pleasant experience! Psychologically, feeding is a bad time for them…

Common problems: limited number of foods, texture preferences and aversions, unusual mealtime habits (self stimulation, has to be in a certain container, has to be from a certain restaurant, rituals)

How to help:

Get them comfortable with the environment first. Sit at the table and color, play, watch the noise level, the stimulation, etc.

Gradual progression (put the table in a more comfortable environment)

goal to sit for longer periods at the table, without food, gradually add in things such as utensils, plate, cup, then last is food! Don’t overwhelm or overstimulate them at meal times, gradually add in everything…’

Reward for food acceptance, sitting at the table, touching foods for fun, etc.

Play time with foods is essential…

Let the child be in more control of the situation (learn to feed themselves and be in control)

Don’t feed a 5 year old and watch what you feed them (mush: oatmeal, baby food, etc.)

Common myths:

1. If a child is hungry enough he will eat. NOT TRUE WITH AUTISM AND SID problems. A therapist in Denver is being sued because she recommended that the mom take away foods and the child should eat what everyone else is eating. The child did not eat for 3 weeks, in hospital for renal failure.

Difference in Picky eater and a problem feeder:

Picky eater: decreased variety of foods less than 30 foods. Foods lost due to burn out regained after 2 weeks, able to tolerate new foods on plate, touch, and taste. Eats at least 1 food of each texture, adds new foods after 15-25 tries or seeing the food.

Problem eater: less than 20 foods eaten, foods not regained once burned out, falls apart when presented with new foods, refuses entire category of textures, adds new foods in more than 25 tries.

Problem eaters are this way because of:

Physical: pain, discomfort, nausea, stool issues, allergies, sensitivities, intolerance

Motor: delayed self feeding, over stuffing, choking, delayed chew, tongue, swallow coordination

Sensory: texture hypersensitivity, oral hypersensitivity, oral aversion, sensory processing problems, auditory (hurts to hear the crunching sounds, or the sounds in the meal room), too stimulating

Behavioral: hyperactive, low frustration tolerance, highly distractable, need for routine, impaired social interactions. If they can’t sit in a chair any other time, why would they sit there to eat for 15 minutes or longer?

Impaired social skills: eating meals is very social, they have to answer questions, look at others, possibly touch one another…

Parenting factors:

poor reinforcement, use positive reinforcement only!

Social modeling (parents must be sitting for the meal and making good food choices as well)

don’t be inconsistent: need structured meals (PECS or visual calendar is very helpful of course)

organized household

NOT allowed to graze all day long

Home based treatment:

Pre-requisite:

identify and treat GI problems (without medicine or band-aids, get to the real problem)

Evaluate motor, oral motor and swallowing skills and treat this area

Evaluate and treat Sensory Integration processes

Conduct a Behavioral Functional Assessment

Get the parents involved in doing it themselves to model your therapists behavior

Develop an individualized intervention plan

General tx strategies: with any child these can be done!

1. Social modeling: the family eating together, not the child eating separately from the child. Have the family come for part of the meal, so there is an overlap of time together if SI issues.

2. Structure meal and snack times: NO MORE GRAZING. Sit down for eating together at set times in the day.

3. Manageable foods: look at the plate, don’t put more than 3 foods at a time, 1 tblsp for each year of age and no more! They become visually overwhelmed!

4. Positive reinforcement: don’t say don’t, say “do this…”

5. appropriate mealtime language: words mean a lot, don’t beg them to take foods (they will take control and say “no”) children with disabilities will control with their mouth.

6. prevent “food jags”: real problem with these children…eat the same thing over and over, all of a sudden they stop eating that food and never go back to that food. When it comes back they see it as all new food again, so they get smaller diets. Suggested that from early on, do not give the same food more often, every other day, and change the foods shape, what is with it, etc.

Steps to eating: Introduce food in play away from meal time first…one food at a time…

1. Tolerate: the food is in the room with them, the food is on the other side of the table, being 2 way on table, with food in front of the table, look at the food directly in front of food.

2. Interact: assists in preparation, uses utensils to stir or play with the food, uses utensils or containers to serve self

3. Smells:

4. Touches: play!

5. Taste: spit bucket handy

6. Eat & swallow

Remember, a child has to interact with a food about 20 times before they will eat it usually!

When they aren’t ready for the next step they use escape mechanisms such as tantrums, run away, scream, be goofy, make you laugh, get another toy…

What is appropriate mealtime language: Choose to ….

And parents and therapists need to remember that:

Feeding problems are not a sprint, a marathon, enjoy the successes along the way!

The SOS (Sequential Oral Sensory) Approach to Feeding notes:

Once the child can tolerate BEING at the table with a food (you have successfully played with a food and they can tolerate being near it) then do the following:

1. do not EVER let the child see the package or container that the food came in, always put it in a ziploc bag, or clear container&they will start to associate the container with the food soon, and then will only eat foods out of that exact container.

2. Do not ever force feed

3. Always make it fun and non stressful

4. Provide a lot of deep pressure touch through massage or brushing and calming choices at mealtime

5. Use a white plate, and white napkin to present foods

6. Let the child cover up the food with the napkin if they don’t like it but offer another way to interact with it through play, it is good in this sense to play with your food!!!!

Give the child a “SAFE FOOD” this is a food that they normally eat and enjoy such as chicken. Introduce a new food that is either the same color or the same texture to that child with the safe food, such as chicken with apple chips close to the same color, other examples: green beans and green snapeas (baked snapeas), or potatoe chips and the same color of dried fruit such as pineapple or banana, or green beans and peas, carrots and sweet potatoes

It can be the same color, shape, or texture as the “safe food”. Keep talking about how the two foods are the same all through the session and mealtime. Even making PECS and do a matching game of those that are the same. The idea is the convey that the new food is also safe, because it is the same as the food they normally eat.

Save chewy or sweet foods and any drinks for after the meal is eaten only, do not let the child fill up on snacks, juices, milks, or other drinks or snacks in between meals. Make meal time a priority 3 times a day to sit and work on skills. Sweets, drinking, and chewy foods fill the child up quickly, but make them hungry again without giving them the nutrition their brains and bodies need. Then they learn to snack, graze, and drink to get calories instead of eating well balanced meals.

Bibliography

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 4th ed. Washington, D.C.: APA, 1994.

Barnett, Samuel Anthony. The Rat: A Study in Behavior. Chicago: Aldine, 1963. Description of bait shyness.

Bernstein, Ilene L., and Mary M. Webster. “Learned Food Aversions: A Consequence of Cancer Chemotherapy.” In Cancer, Nutrition, and Eating Behavior. Edited by Thomas G. Burish, Sandra M. Levy, and Beth E. Meyerowitz. Hillsdale, N.J.: Lawrence Erlbaum, 1985.

Garcia, John, and Andrew R. Gustavson. “Carl R. Gustavson (1946–1996) Pioneering Wildlife Psychologist.” APS Observer ( January 1997): 34–35. This paper and ones by C. R. Gustavson describe work on training coyotes to avoid sheep.

Garcia, John, Donald J. Kimeldorf, and Robert A. Koelling. “Conditioned Aversion to Saccharin Resulting from Exposure to Gamma Radiation.” Science 122 (1955): 157–158.

Garcia, John, and Robert A. Koelling. “Relation of Cue to Consequence in Avoidance Learning.” Psychonomic Science 4 (1966): 123–124. Paper showing it is easier to associate tastes than audiovisual stimuli with illness.

Gustavson, Carl R. “Comparative and Field Aspects of Learned Food Aversions.” In Learning Mechanisms in Food Selection. Edited by L. M. Barker, M. R. Best, and M. Domjan. Waco, Tex.: Baylor University Press, 1977.

Gustavson, Carl R., Linda P. Brett, John Garcia, and Daniel J. Kelly. “A Working Model and Experimental Solutions to the Control of Predatory Behavior.” In Behavior of Captive Wild Animals. Edited by H. Markowitz and V. J. Stevens. Chicago: Nelson-Hall, 1978.

Logue, A. W. The Psychology of Eating and Drinking: An Introduction. 2d ed. New York: W. H. Freeman, 1991. General text including information on origins, characteristics, and applications of food aversions.

Logue, A. W. “Taste Aversion and the Generality of the Laws of Learning.” Psychological Bulletin 86 (1979): 276–296.

Logue, A. W., Iris Ophir, and Kerry E. Strauss. “The Acquisition of Taste Aversions in Humans.” Behavior Research & Therapy 19 (1981): 319–333.

Nakajima, S., H. Ka, and H. Imada. “Summation of Overshadowing and Latent Inhibition in Rats’ Conditioned Taste Aversion: Scapegoat Technique Works for Familiar Meals.” Appetite 33 (1999): 299–307.

Rozin, Paul. “The Selection of Foods by Rats, Humans, and Other Animals.” In Advances in the Study of Behavior, edited by J. S. Rosenblatt, R. A. Hinde, E. Shaw, and C. Beer. Vol. 6. New York: Academic Press, 1976. Description of specific hungers.

Rozin, P., and April Fallon. “The Psychological Categorization of Foods and Non-Foods: A Preliminary Taxonomy of Food Rejections.” Appetite 1 (1980): 193–201.

Seligman, Martin E. P., and Joanne L. Hager, eds. Biological Boundaries of Learning. New York: Appleton-Century-Crofts, 1972. Description of sauce béarnaise phenomenon.

Wiens, Arthur N., and Carol E. Menustik. “Treatment Outcome and Patient Characteristics in an Aversion Therapy Program for Alcoholism.” American Psychologist 38 (1983): 1089–1096.


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