Effects Of Taste Genetics On Food Acceptance

Taste Genetics & Food Taste Genetics & Food AcceptanceAcceptance

Trey Sanders, BSFCSTrey Sanders, BSFCS

[email protected]@gmail.com

October 8, 2009October 8, 2009

OutlineOutline Taste GeneticsTaste Genetics

Underlying mechanismsUnderlying mechanisms BiomarkersBiomarkers Types of cellular & animal studiesTypes of cellular & animal studies Types of human studiesTypes of human studies Gaps in knowledgeGaps in knowledge

Taste DisordersTaste Disorders Who taste disorders affect?Who taste disorders affect? DiagnosisDiagnosis Underlying mechanismsUnderlying mechanisms TreatmentsTreatments PreventionsPreventions

OutlineOutline

Food Acceptance Definition Dietary guidelines & reference intakes Health risks & medication interaction Gaps in knowledge

Presentation Paper (Duffy & Presentation Paper (Duffy & Bartoshuk, 2000)Bartoshuk, 2000)

Is there a Relationship?Is there a Relationship?

Different perceptions of sweetness Different perceptions of sweetness and bitterness influence consumer’s and bitterness influence consumer’s preferences in foodspreferences in foods

Potentially impacts acceptance of foods that are particularly high or low fat, sweet, or bitter

Duffy & Bartoshuk, 2000; Mennella et al., 2005; Mennella et al., 2005

Chemical FormsChemical Forms

Phenylthiocarbamide (PTC) Chemical involved with bitterness

perception 6-n-propylthiouracil (PROP)

Chemical relative of PTC Varying perception of these

chemicals due to a genetic variation The bitter receptor TAS2R38

Zhao et al., 2007; The Interactive Library, 1999; Chemical Book, 2007

Taste & GeneticsTaste & Genetics

Perceived bitterness stems from the Perceived bitterness stems from the ability to taste compounds that contain ability to taste compounds that contain a N-C=S group a N-C=S group i.e. PTC and PROP i.e. PTC and PROP

Non-tasters vs. tastersNon-tasters vs. tasters Supertasters- a smaller population that has Supertasters- a smaller population that has

an extreme sensitivity to PROP an extreme sensitivity to PROP Degree of sensitivity to bitterness is Degree of sensitivity to bitterness is

associated with preference of certain sweet associated with preference of certain sweet or bitter foods or bitter foods

Mennella et al., 2005


Ability to taste PROP is from a Ability to taste PROP is from a dominant allele, which splits people dominant allele, which splits people into three groups: into three groups: Homozygous dominant Homozygous dominant Heterozygous dominant Heterozygous dominant Homozygous recessive Homozygous recessive

Does not necessarily mean that all people Does not necessarily mean that all people homozygous dominant alleles for PROP are homozygous dominant alleles for PROP are supertasters supertasters

Basson et al., 2005; Kids Do Science, 2002Basson et al., 2005; Kids Do Science, 2002

Taste & Genetics

PROP bitterness correlates with PROP bitterness correlates with fungiform papillae densityfungiform papillae density Structures that hold taste buds Structures that hold taste buds Anterior 2/3 of tongueAnterior 2/3 of tongue Supertasters tend to have the highest Supertasters tend to have the highest

density of these papillae and taste buds density of these papillae and taste buds on these papillaeon these papillae

Basson et al., 2005Basson et al., 2005


Variation in taste sensitivity for Variation in taste sensitivity for bitterness stems from T2R genesbitterness stems from T2R genes

Receptors involved mainly respond Receptors involved mainly respond to plant secondary compoundsto plant secondary compounds

Created by plants that are poisonous Created by plants that are poisonous or undesirable to predators or undesirable to predators

Supertasters tend not to like Supertasters tend not to like vegetables because they contain vegetables because they contain bitter secondary compoundsbitter secondary compounds

Mennella et al., 2005; Garcia-Bailo et al., 2009; Krebs, Mennella et al., 2005; Garcia-Bailo et al., 2009; Krebs, 20092009

BiomarkersBiomarkers

Measuring a person’s sensitivity to PTC or PROP Defining the degree of sensitivity

Zhao et al., 2007

Types of Cellular & Animal Types of Cellular & Animal StudiesStudies

Bitterness- not readily available Bitterness- not readily available through searchesthrough searches

Animal studies used in process of Animal studies used in process of other modalities other modalities Helpful, but not perfectHelpful, but not perfect

Krebs, 2009; Garcia-Bailo et al., 2009

Types of Human StudiesTypes of Human Studies

Not able to identify randomized Not able to identify randomized control trial studiescontrol trial studies

Other types of human studies:Other types of human studies: Convenience sample (Duffy & Convenience sample (Duffy &

Bartoshuk, 2000)Bartoshuk, 2000) Sequential cohort (Basson et al., 2005)Sequential cohort (Basson et al., 2005) Cross sectional (Zhao et al., 2007, Cross sectional (Zhao et al., 2007,

Menella et al., 2005) Menella et al., 2005)

Krebs, 2009

Gaps in KnowledgeGaps in Knowledge

Not every part of the population is Not every part of the population is equally divided into 25% nontasters, equally divided into 25% nontasters, 50% tasters, and 25% supertasters 50% tasters, and 25% supertasters About 70% tasters and 30% non-tasters

in North Americans and Western Europeans

Trying to understand the genetic Trying to understand the genetic variation throughout different variation throughout different populations is still unknownpopulations is still unknown

Krebs, 2009; Krebs, 2009; Zhao et al., 2007

Taste DisordersTaste Disorders

Evergreen Science Center, 2008

What is a Taste What is a Taste Disorder?Disorder?

Involves a variety of conditions Involves a variety of conditions including:including: Experiencing phantom perceptionsExperiencing phantom perceptions Hypogeusia- a reduced ability to tasteHypogeusia- a reduced ability to taste Ageusia- not detecting a taste at allAgeusia- not detecting a taste at all System misreading or distorting tastesSystem misreading or distorting tastes Detecting a bad taste from normally Detecting a bad taste from normally

pleasant tasting foodspleasant tasting foods

National Institute of Deafness and other Communication Disorders, 2002

Who do Taste Disorders Who do Taste Disorders Affect?Affect?

BirthBirth Structure malformationStructure malformation

After an injury or illnessAfter an injury or illness AgingAging

Taste perception and function decrease Taste perception and function decrease Prevalence not availablePrevalence not available

Varying methods at which conclusions Varying methods at which conclusions for taste disorders have been drawnfor taste disorders have been drawn

National Institute of Deafness and other Communication Disorders, 2002; National Institute of Deafness and other Communication Disorders, 2002; National Institute of Deafness and other Communication Disorders, 2008National Institute of Deafness and other Communication Disorders, 2008

Diagnosis of Taste Diagnosis of Taste DisordersDisorders

Some methods include:Some methods include: Determining the lowest concentration Determining the lowest concentration

of a chemical that a person can of a chemical that a person can recognizerecognize

Asking the patient to compare the Asking the patient to compare the tastes of different chemicals tastes of different chemicals

Asking a patient to note the increasing Asking a patient to note the increasing intensity of a taste when the intensity of a taste when the concentration of the chemical is concentration of the chemical is increasedincreased

National Institute of Deafness and other Communication Disorders, National Institute of Deafness and other Communication Disorders, 20022002

Causes of Taste Causes of Taste DisordersDisorders

Some have had since birthSome have had since birth Other causes include:Other causes include:

InjuryInjury Central tumors or lesionCentral tumors or lesion Dental or oral health issues Dental or oral health issues Adverse interactions with medicationsAdverse interactions with medications Perception of chemicals associated with Perception of chemicals associated with

certain tastescertain tastes i.e. PTC or PROP for bitternessi.e. PTC or PROP for bitterness

National Institute of Deafness and other Communication Disorders, 2002; National Institute of Deafness and other Communication Disorders, 2002; National Institute of Deafness and other Communication Disorders, 2008; National Institute of Deafness and other Communication Disorders, 2008; Duffy & Bartoshuk, 2000

Underlying MechanismsUnderlying Mechanisms

Lacking receptor sites for chemicals Lacking receptor sites for chemicals associated with certain tastesassociated with certain tastes

Damage to the central nervous Damage to the central nervous system which is directly involved in system which is directly involved in the innervation of taste budthe innervation of taste bud

Duffy & Bartoshuk; National Institute of Deafness and other Communication Duffy & Bartoshuk; National Institute of Deafness and other Communication Disorders, 2008Disorders, 2008

TreatmentsTreatments

Depends on the cause Depends on the cause Medication: stopping or changing the Medication: stopping or changing the

medication should alleviate the problem medication should alleviate the problem Also true of some illnesses or allergies; Also true of some illnesses or allergies;

their taste perception returns with their taste perception returns with recovery recovery

Correcting a general medical problemCorrecting a general medical problem Occasionally will return spontaneouslyOccasionally will return spontaneously

National Institute of Deafness and other Communication Disorders, National Institute of Deafness and other Communication Disorders, 20022002

PreventionPrevention

Practice good oral hygiene Practice good oral hygiene Have consistent dental appointmentsHave consistent dental appointments There is not a preventative measure There is not a preventative measure

for taste loss associated with agingfor taste loss associated with aging

National Institutes of Health Senior Health, National Institutes of Health Senior Health, 20082008

Food AcceptanceFood Acceptance

http://www.mychildhealth.net/wp-content/uploads/2009/04/kids-vegetable.jpg

Food AcceptanceFood Acceptance

Evaluation of foods based on their degree of Sweetness Bitterness Overall palatability

Duffy & Bartoshuk, 2000

Dietary Guidelines & Dietary Guidelines & Reference IntakesReference Intakes

Dietary Guidelines for Americans Carbohydrates- 45%-65% of total

calories Fats- 20%-35% of total calories

Dietary Reference Intakes Carbohydrates- 130g/day for males &

females ages 1-70 Fats not yet been determined

United States Department of Agriculture, 2005

Health Risks & Medication Health Risks & Medication InteractionsInteractions

Health risks can include: Malnutrition Weight inadequacies Organ system failure Coma Death

Some medications can alter taste acuity Could increase difficulty in already picky

tasters

Mahan & Escott-Stump, 2008

Gaps in KnowledgeGaps in Knowledge Frequency of food acceptance was

inconsistent throughout the studies Status of research based on genetic

variation hard to come by Earlier studies sometimes did not define levels

for tasters Prevalent because food acceptance can

also be affected by: Environmental factors Allergies Religious preferences Dietary preferences

Duffy & Bartoshuk, 2000; Zhao et al., 2007

Food Acceptance Food Acceptance & Genetic & Genetic

Variation on Variation on TasteTaste

IntroductionIntroduction

Authors: Valerie B. Duffy, PhD, RD Authors: Valerie B. Duffy, PhD, RD and Linda M. Bartoshuk, PhD. and Linda M. Bartoshuk, PhD. Published in the Journal of The Published in the Journal of The

American Dietetic Association American Dietetic Association Performed at Yale University in Performed at Yale University in

ConnecticutConnecticut


BackgroundBackground Consumers report that taste is an important Consumers report that taste is an important

factor when selecting foods, though taste is factor when selecting foods, though taste is often used as a broad descriptoroften used as a broad descriptor

Taste can refer to:Taste can refer to: True Taste - the perception of bitter, True Taste - the perception of bitter,

sweet, salty, and soursweet, salty, and sour Retronasal Olfaction- perception of Retronasal Olfaction- perception of

olfactory stimuli from within the oral olfactory stimuli from within the oral cavity cavity

Oral Somatosensation- perception of Oral Somatosensation- perception of touch, temperature, and pain touch, temperature, and pain

Mennella et al., 2005; Mennella et al., 2005; Duffy & Bartoshuk, 2000

BackgroundBackground

Method of measuring perception is Method of measuring perception is not perfect not perfect Can be altered by many factors such as Can be altered by many factors such as

hormonal changes and common hormonal changes and common pathologic conditions pathologic conditions

Authors also use fungiform papillae Authors also use fungiform papillae density because of correlation with density because of correlation with bitterness perceptionbitterness perception

Duffy & Bartoshuk, 2000; Basson et al., 2005

Research QuestionResearch Question

Is there a contribution of genetic Is there a contribution of genetic variation in taste to liking of sweet, variation in taste to liking of sweet, fat, and bitter foods and beverages?fat, and bitter foods and beverages?


Hypothesis

People who taste PROP as People who taste PROP as exceptionally bitter and have a high exceptionally bitter and have a high density of fungiform papillae have a density of fungiform papillae have a different oral sensory world from different oral sensory world from those who taste less PROP bitterness those who taste less PROP bitterness relative to density of fungiform relative to density of fungiform papillaepapillae Relationship will produce a difference in Relationship will produce a difference in

preference for sweet, fat, or bitter foods preference for sweet, fat, or bitter foods and beveragesand beverages


Aims of StudyAims of Study

Identify a relationship betweenIdentify a relationship between Fungiform papilla densityFungiform papilla density PROP bitterness PROP bitterness Acceptance of foods and beverages Acceptance of foods and beverages

with varying bitter, sweet, and fat with varying bitter, sweet, and fat contentcontent


MethodsMethods Convenience sample of 70 healthy adults Convenience sample of 70 healthy adults

recruited by advertising in a university recruited by advertising in a university community community

Subjects completed a taste related health Subjects completed a taste related health questionnaire including weight and height for questionnaire including weight and height for BMI calculation, a food acceptance survey, and BMI calculation, a food acceptance survey, and the restraint scale the restraint scale 10 subjects were excluded due to a hearing 10 subjects were excluded due to a hearing

impairment impairment 14 subjects were excluded because of high dietary 14 subjects were excluded because of high dietary

restraint, disinhibition, and weight fluctuation restraint, disinhibition, and weight fluctuation Remaining 46 subjects classified as 24 women & 22 Remaining 46 subjects classified as 24 women & 22

men, 8 Asian Americans, 7 African Americans, 24 men, 8 Asian Americans, 7 African Americans, 24 Caucasians, 6 Latin Americans and 1 Asian Indian Caucasians, 6 Latin Americans and 1 Asian Indian


Research DesignResearch Design Deionized water was used to prepare all Deionized water was used to prepare all

PROP and NaCl solutions and served as a PROP and NaCl solutions and served as a rinse before each stimulus rinse before each stimulus

Threshold testing: two alternative forced Threshold testing: two alternative forced choice, up-down detection thresholdschoice, up-down detection thresholds PROP solutions ranging in quarter log steps from PROP solutions ranging in quarter log steps from

0.000001 to 0.0032 mol/L 0.000001 to 0.0032 mol/L Concentrations were decreased only after 2 Concentrations were decreased only after 2

correct choices but were increased after one correct choices but were increased after one incorrect choiceincorrect choice

Suprathreshold testing (occurred after Suprathreshold testing (occurred after threshold testing): subjects used magnitude threshold testing): subjects used magnitude estimation to indicate intensity of quarter-estimation to indicate intensity of quarter-log steps of solutions and 1,000 Hz toneslog steps of solutions and 1,000 Hz tones


Research DesignResearch Design

Subjects asked to rate all stimuli on a Subjects asked to rate all stimuli on a common scale of intensitycommon scale of intensity PROP solutions were presented after PROP solutions were presented after

NaCl solutions to prevent context effects NaCl solutions to prevent context effects Subjects then assigned numbers to Subjects then assigned numbers to

adjectives: “very strong,” “strong,” adjectives: “very strong,” “strong,” “moderate,” “weak,” and “very weak”.“moderate,” “weak,” and “very weak”.

PROP ratings normalized with the tone PROP ratings normalized with the tone ratings that followed the NaCl series ratings that followed the NaCl series


Research DesignResearch Design

For fungiform papillae counts, a methylene For fungiform papillae counts, a methylene blue stain was applied to the anterior portion blue stain was applied to the anterior portion of the tongueof the tongue Images were recorded through an operating Images were recorded through an operating

microscope and counted in a 3x3-mm area to the microscope and counted in a 3x3-mm area to the right of the midline at the tongue tip right of the midline at the tongue tip

Subjects completed an 83-item survey Subjects completed an 83-item survey consisting of foods from all major food groups consisting of foods from all major food groups using a hedonic scale using a hedonic scale Instructed to circle “like” or “dislike” for each item Instructed to circle “like” or “dislike” for each item

and then mark line length on a 200 mm line to and then mark line length on a 200 mm line to indicate the degree of liking or disliking indicate the degree of liking or disliking


Food Liking/Disliking Groups


ResultsResults Data were analyzed with Data were analyzed with

STATISTICA, P < 0.05 STATISTICA, P < 0.05 Perceived bitterness of PROP Perceived bitterness of PROP

did not correlate significantly did not correlate significantly with body weight, height or BMI with body weight, height or BMI in either sex in either sex

Fungiform papillae density Fungiform papillae density correlated significantly with BMI correlated significantly with BMI in men (r = 0.50)in men (r = 0.50)


Results

Based on perceived bitterness of Based on perceived bitterness of 0.0032 mol/L PROP:0.0032 mol/L PROP:12 nontasters (5 Women, 7 Men) 12 nontasters (5 Women, 7 Men) 22 medium tasters (10 Women, 12 22 medium tasters (10 Women, 12

Men) Men) 12 supertasters (9 Women, 3 Men)12 supertasters (9 Women, 3 Men)

Women reported highest perceived Women reported highest perceived bitterness for the 0.0032 mol/L PROPbitterness for the 0.0032 mol/L PROP


ResultsResults

Fungiform papillae density correlated Fungiform papillae density correlated significantly with perceived bitterness of significantly with perceived bitterness of PROP (P < 0.05)PROP (P < 0.05)

Women showed greatest variance in the Women showed greatest variance in the residuals from the regression analysis of residuals from the regression analysis of PROP bitterness on funigform papillae PROP bitterness on funigform papillae density (P < 0.01)density (P < 0.01) Significance in funigform papillae density Significance in funigform papillae density

distribution for men was displaced toward distribution for men was displaced toward lower densities (P < 0.05)lower densities (P < 0.05)


Results, Table 3Results, Table 3


Results, continuedResults, continued Perceived bitterness of PROP showed Perceived bitterness of PROP showed

significant correlations with liking of sweets, significant correlations with liking of sweets, fruits, and natural sweets fruits, and natural sweets Negative correlations for women Negative correlations for women Positive correlation for men (just showed Positive correlation for men (just showed

significance in fruits) significance in fruits) Significant negative correlation between liking Significant negative correlation between liking

of sweets and increased PROP bitterness in of sweets and increased PROP bitterness in womenwomen

Women who perceived PROP bitterness did not Women who perceived PROP bitterness did not like fat1, fat2, or cheese significantlylike fat1, fat2, or cheese significantly Men who perceived PROP bitterness significantly Men who perceived PROP bitterness significantly

liked fat1 liked fat1


Results, continuedResults, continued Significant negative correlation between liking Significant negative correlation between liking

of fat and increasing PROP bitterness for of fat and increasing PROP bitterness for women women

Significant positive correlation in men between Significant positive correlation in men between liking/disliking fat foods and fungiform papillae liking/disliking fat foods and fungiform papillae density density

Neither measure correlated significantly with Neither measure correlated significantly with liking/disliking of bitter beverages or liking/disliking of bitter beverages or cruciferous vegetablescruciferous vegetables

Women and men had significant positive Women and men had significant positive correlation between liking/disliking of the correlation between liking/disliking of the vegetable group and fungiform papillae densityvegetable group and fungiform papillae density


DiscussionDiscussion

Authors felt they hadAuthors felt they had Better classification of liking/disliking Better classification of liking/disliking

foods to help eliminate the ceiling factor foods to help eliminate the ceiling factor Better classification of nontasters, Better classification of nontasters,

medium tasters, and supertastersmedium tasters, and supertasters Associations between PROP Associations between PROP

bitterness and both sweet & fat bitterness and both sweet & fat preference in women might be preference in women might be related to hormonal variationrelated to hormonal variation


Discussion

Fungiform papilla count was from too Fungiform papilla count was from too small of an area to provide a stronger small of an area to provide a stronger correlation with PROP bitterness correlation with PROP bitterness

Impact of taste genetic variation on Impact of taste genetic variation on food acceptance depends on food acceptance depends on interactions between genetic traits interactions between genetic traits and non-sensory influences and non-sensory influences Could also account for the differences Could also account for the differences

between women and menbetween women and men


LimitationsLimitations

Small sample sizeSmall sample size Small papillae area countSmall papillae area count Control of non-sensory influencesControl of non-sensory influences

Prior associations with certain kinds of Prior associations with certain kinds of foodsfoods

Experimenter biasExperimenter bias True dietary disinhibition True dietary disinhibition


Future Future RecommendationsRecommendations

How much other factors play along with How much other factors play along with genetic variation in determining food genetic variation in determining food acceptance acceptance RaceRace Age Age Sex Sex

Role of hormones in women’s food Role of hormones in women’s food acceptanceacceptance

Bigger sample size Bigger sample size Larger area for fungiform papillae countingLarger area for fungiform papillae counting

Duffy & Bartoshuk, 2000; Krebs, Krebs, 20092009

Implications for Consumers Implications for Consumers & Patients & Patients

Food preferences & patterns may be Food preferences & patterns may be related to genetic predisposition related to genetic predisposition rather than not understanding healthy rather than not understanding healthy eatingeating Dietary interventions can ultimately come Dietary interventions can ultimately come

back to how enjoyable the foods and back to how enjoyable the foods and beverages are despite knowing its health beverages are despite knowing its health benefitsbenefits

Genetic variation is one of many Genetic variation is one of many factors that influence oral sensationfactors that influence oral sensation


Questions?Questions?

Q&AQ&A What were the genetic markers used to assess What were the genetic markers used to assess

taste? taste? Perceiving of PROP bitterness and Perceiving of PROP bitterness and Fungiform Papillae densityFungiform Papillae density

In Table 3, what category had opposite In Table 3, what category had opposite correlation significance for women and men? correlation significance for women and men? Fruits; Negative correlation for women and Fruits; Negative correlation for women and Positive Correlation for MenPositive Correlation for Men

Which sex showed a significant negative Which sex showed a significant negative correlation between PROP bitterness and liking correlation between PROP bitterness and liking of sweets? of sweets? WomenWomen

Which category showed a significant positive Which category showed a significant positive correlation with fungiform papillae density in correlation with fungiform papillae density in men? men? Fat AverageFat Average

ReferencesReferences Basson MD, Bartoshuk LM, Dichello SZ, Panzini L, Weiffenbach Basson MD, Bartoshuk LM, Dichello SZ, Panzini L, Weiffenbach

JM, Duffy VB. Association between 6-n-propylthiouracil (PROP) JM, Duffy VB. Association between 6-n-propylthiouracil (PROP) bitterness and colonic neoplasms. Dig Dis Sci. 2005(50):483-9.bitterness and colonic neoplasms. Dig Dis Sci. 2005(50):483-9.

Chemical Book. 2007. Propylthiouracil Product Description. Chemical Book. 2007. Propylthiouracil Product Description. Retrieved September 30, 2009 from Retrieved September 30, 2009 from www.chemicalbook.com/CAS%5CGIF%5C51-52-5.gifwww.chemicalbook.com/CAS%5CGIF%5C51-52-5.gif

Duffy VB, Bartoshuk LM. Food acceptance and genetic variation Duffy VB, Bartoshuk LM. Food acceptance and genetic variation in taste. JADA. 2000;100(6):647-55.in taste. JADA. 2000;100(6):647-55.

Evergreen Sinus Center. 2008. Smell and Taste. Retrieved Evergreen Sinus Center. 2008. Smell and Taste. Retrieved October 2, 2009 from October 2, 2009 from http://www.evergreensinus.com/condition-smell-taste-http://www.evergreensinus.com/condition-smell-taste-evergreen-sinus-center-kirkland-washington.htm evergreen-sinus-center-kirkland-washington.htm

Garcia-Bailo B, Toguri C, Eny KM, El-Sohemy A. Genetic Garcia-Bailo B, Toguri C, Eny KM, El-Sohemy A. Genetic variation in taste and its influence on food selection. OMICS. variation in taste and its influence on food selection. OMICS. 2009 Feb;13(1):69-80. Review2009 Feb;13(1):69-80. Review

Kids Do Science. 2002. Genetic Puppets. Retrieved October 2, Kids Do Science. 2002. Genetic Puppets. Retrieved October 2, 2009 from 2009 from http://www.uga.edu/srel/kidsdoscience/kidsdoscience-genetics-http://www.uga.edu/srel/kidsdoscience/kidsdoscience-genetics-puppets.htm puppets.htm

References Krebs JR. The gourmet ape: evolution and human food Krebs JR. The gourmet ape: evolution and human food

preferences. Am J Clin Nutr. 2009 Sep;90(3):707S-711S.preferences. Am J Clin Nutr. 2009 Sep;90(3):707S-711S. Lahteenmaki L, Tuorila H. Three-factor eating questionnaire Lahteenmaki L, Tuorila H. Three-factor eating questionnaire

and the use and liking of sweet and fat among dieters. and the use and liking of sweet and fat among dieters. Physiol Behav. 1995; 57:81-88.Physiol Behav. 1995; 57:81-88.

Mahan, L.K., & Escott-Stump, S. (2008). Krause’s Food & Nutrition Therapy. St. Louis: Saunders Elsevier.

Mennella JA, Pepino Y, Reed DR. Genetic and environmental Mennella JA, Pepino Y, Reed DR. Genetic and environmental determinants of bitter perception and sweet preferences. determinants of bitter perception and sweet preferences. Pediatrics. 2005;115(2):E216–222.Pediatrics. 2005;115(2):E216–222.

My Child Health. How to get kids to eat their vegetables. My Child Health. How to get kids to eat their vegetables. Retrieved October 2, 2009 from Retrieved October 2, 2009 from http://www.mychildhealth.net/wp-content/uploads/2009/04/kihttp://www.mychildhealth.net/wp-content/uploads/2009/04/kids-vegetable.jpg ds-vegetable.jpg

National Institute of Deafness and other Communication National Institute of Deafness and other Communication Disorders. 2002. Internet. Disorders. 2002. Internet. http://www.nidcd.nih.gov/health/smelltaste/taste.asp http://www.nidcd.nih.gov/health/smelltaste/taste.asp (accessed 26 August 2009).(accessed 26 August 2009).

ReferencesReferences National Institute of Deafness and other Communication National Institute of Deafness and other Communication

Disorders. 2008. Internet. Disorders. 2008. Internet. http://www.nidcd.nih.gov/health/statistics/taste.asp (accessed http://www.nidcd.nih.gov/health/statistics/taste.asp (accessed 26 August 2009).26 August 2009).

National Institutes of Health Senior Health. 2008. Internet. National Institutes of Health Senior Health. 2008. Internet. http://nihseniorhealth.gov/problemswithtaste/causesandpreventhttp://nihseniorhealth.gov/problemswithtaste/causesandprevention/08.html (accessed 26 August 2009). ion/08.html (accessed 26 August 2009).

The Interactive Library. 1999. Interactive Molecules: The Interactive Library. 1999. Interactive Molecules: Phenylthiocarbamide. Retrieved September 30, 2009 from Phenylthiocarbamide. Retrieved September 30, 2009 from http://www.edinformatics.com/interactive_molecules/3D/ptc_mohttp://www.edinformatics.com/interactive_molecules/3D/ptc_molecule.htmlecule.htm

United States Department of Agriculture. 2005. Dietary Reference Intakes: Macronutrients. Internet. http://www.iom.edu/Object.File/Master/7/300/Webtablemacro.pdf (accessed September 2, 2009).

Zhao L, Tepper BJ. Perception and acceptance of selected high-Zhao L, Tepper BJ. Perception and acceptance of selected high-intensity sweeteners and blends in model soft drinks by intensity sweeteners and blends in model soft drinks by propylthiouracil (PROP) non-tasters and super-tasters. Food propylthiouracil (PROP) non-tasters and super-tasters. Food Quality and Preference. 2007;18(3):531-40. Quality and Preference. 2007;18(3):531-40.

Technology

Effects Of Taste Genetics On Food Acceptance