similarity of children's and their parents‘ food preferences

The possibility that a subfraction of im- munoalobulins mav be involved in ribofla-

lian Riboflavin-Binding Proteins in Flavins and Flavoproteins. V Massey and CH Wil-

vin biiding was suggested by the observa- tion of the poor correlation between the total concentration of IgG and IgA and ribo- flavin binding. These findings suggested that riboflavin-binding immunoglobulins are a major cause of variations in riboflavin binding in human circulation and may therefore affect the utilization of this mi- cronutrient. The marked changes in ribofla- vin binding seen in certain states such as pregnancy and cancer may be related to al- teration in riboflavin-binding immunoglob- ulins.

In a more recent paper from the same laboratory, Innis et ale reported elevated levels of riboflavin-binding globulins in plasma from cancer patients. This may ex- plain the lower urinary excretion of ribofla- vin in cancer patients reported earlier. Here again the correlation between riboflavin- binding and total immunoglobulin concen- tration was weak. Unfortunately, the EGR- index and riboflavin concentration in erythrocytes and plasma of cancer patients were not examined. These measurements might have provided better insight into the role of riboflavin-binding immunoglobulins in regulating tissue distribution of ribofla- vin.

1. AH Merrill, Jr, G. Shapira, and DB McCor- mick: Recent Findings Concerning Mamma-

liams, Editors, pp 508-513. Elsevier, North Holland, 1982

2. AH Merrill, Jr, JA Froehlich, and DB McCor- mick: Purification of Riboflavin-Binding Proteins from Bovine Plasma and Discovery of a Pregnancy-Specific Riboflavin-Binding Protein. J Biol Chem 254: 9362-9364, 1979

3. K Muniyappa and PR Adiga: Occurrence and Functional Importance of a Riboflavin- Carrier Protein in the Pregnant Rat. FEBS Lett 110: 209-212, 1980

4. B DurgaKumari and PR Adiga: Hormonal In- duction of Riboflavin-Carrier Protein in the Chicken Oviduct and Liver: A Comparison of Kinetics and Modulation. Mol Cell Endo- crinol44: 285-292, 1986

5. M Ferhangi and EF Osserman: Myeloma with Xanthoderma Due to an IgG Monoclo- nal Anti-Flavin Antibody. N Engl J Med 294: 177-1 83. 1976

6. AH Merrill, Jr, JA Froehlich, and DB McCor- mick: Isolation and Identification of Alter- native Riboflavin-Binding Proteins from Human Plasma. Biochem Med 25: 198-206, 1981

7. WSA Innis, DB McCormick, and AH Merrill, Jr: Variations in Riboflavin Binding by Human Plasma: Identification of Immuno- globulins as the Major Proteins Responsi- ble. Biochem Med 34: 151-165, 1985

8. WSA Innis, DW 'Nixon, DR Murray, DB McCormick, and AH Merrill: Immunoglobu- lins Associated with Elevated Riboflavin Binding by Plasma from Cancer Patients. Proc SOC Exp Biol Med 181 : 237-241, 1986

SIMILARITY OF CHILDREN'S AND THEIR PARENTS' FOOD PREFERENCES

Children's and their parents' food preferences tend to be similar, but how much of this similarity is due to genetic and how much to environmental

factors is unclear.

Key Words: food preferences, children, parents, families, heredity, environment

The determinants of food preferences in humans have not been studied to a degree commensurate with the amount of popular

interest in this subject. While there have been many studies examining the origins of specific taste preferences in humans,112 research on preferences for actual foods has been extremely limited until recently. The increased number of such research in-

134 NUTRITION REVIEWSIVOL 45, NO !WAY 1987

vestigations, particularly among psycholo- gists, are essential for promoting good health because they may result in ways to modify undesirable food preferences.

To what extent are the origins of food preferences due to genetic factors and to what extent to environmental factors? If genetic factors are more influential, people from the same family should demonstrate more similar food preferences than people from different families. Such similarities could also occur because of certain envi- ronmental influences among family members such as observational learning, instruc- tions, and assortative mating. Thus, one step in identifying genetic effects on food preferences is to look for similarity among food preferences of family members; how- ever, finding such a correlation would not exclude some types of environmental ef- fects as well.

Recent studies looking for family similar- ities with regard to food preferences can be divided into two groups, namely, those that compare young children’s preferences with those of their parents, and those that com- pare college students’ preferences with those of their parents. Four studies within the first group have obtained mixed results, with two studies3s4 demonstrating signifi- cant similarities between the young chil- dren’s and their parents’ food preferences and two studies5g6 showing few similarities. Within the second group two recent stud- ies7s8 have each demonstrated significant similarities between college students’ and their parents’ food preferences.

Therefore, there is at least some indica- tion of genetic influence(s) on food prefer- ences. All studies, even those that did not find significant family similarities, tended to find positive rather than negative corre- lations between the children and their par- ents’ food preferences, as well as between the children and other children’s parents. This has been interpreted as evidence that most members of a cultural group have many food preferences in ~ o m m o n , ~ which could be due to genetic factors, environ- mental factors, or both.

The question remains as to why some

studies obtained significant child-parent similarities and some did not. Many meth- odological problems could have obscured such similarities. The ways in which food preferences were determined is one exam- ple. Both studies with college student^^.^ asked each student and each parent sepa- rately to report his or her food preferences on a written questionnaire, and each food was rated on a seven-point7 or nine-points scale. However, only two of the studies with children used this type of methodology, one with a three-point scale3 and one with a five-point scale.6 In Pliner and Pelchat’s study,4 mothers rated their own food pref- erences as well as the food preferences of their husbands and children. Nevertheless, despite the lack of first-hand reports from most of the subjects under study, this in- vestigation still obtained greater food pref- erence similarity between children and their parents than between children and other children’s parents.

In Birch’s5 study among young children, foods were ranked from the most-preferred to the least-preferred, rather than each food being rated separately. With this pro- cedure, if study subjects tend to like and dislike the same foods, there will be no sig- nificant differences between child-parent similarity and child-other child’s parent similarity. In addition, only one measure- that relating the child’s rankings to the par- ent’s rankings-can be obtained for each child-parent pair; child-parent similarities cannot be examined for individual foods and possible genetic influences on specific food preferences cannot be identified. When the foods are rated separately, even if study subjects tend to rank the foods in the same way, differences between child- parent and child-other child’s parent simi- larities could still be detected. That is, child-parent similarity can be measured separately for each food, so that even if some food preferences are not similar be- tween children and their parents, it is still possible to observe similarities for other food preferences. Considering that Birch used a ranking procedure, it is perhaps not surprising that she obtained no more simi-

NUTRITION REVIEWSIVOL 45, NO 5IMAY 7987 135

larity for child-parent than for child-other child’s parent food preference compari- sons.

Of all the studies reported here, only Birch’s5 study involved preferences ob- tained following actual tasting of the food. In the other studies, subjects had to recall their preferences. Therefore, i t is not known i f the similarities obtained in the other studies could be partially due to faulty memories. Further, we do not know to what degree reported preferences reflect actual preferences and actual consump- tion. Results from Weidner et al’s6 study in- dicate that for five low-cholesterol foods stated food preferences and frequency of consumption were not related.

The actual foods chosen for a question- naire can also influence the results. The number of foods investigated by the stud- ies reviewed here ranged between five6 and 139.4 Because Weidner et al’s study only looked at five foods, there would not have been much opportunity for that study to demonstrate family similarity. However, that study had the limited goal of examin- ing food preferences for only a few low- cholesterol foods.

Of the six studies reviewed, only one8 specifically limited the sample to biologi- cally related children and parents. The ex- istence of a biologic relationship between the children and their parents was not de- termined by Pliner7, while the other four ~ t u d i e s ~ - ~ never discussed this point at all. It would have been helpful in the studies 0.n college student^^.^ if the researchers had separated those children who had had many of their meals with their parents from those who had not (eg, those who had at- tended boarding school and summer sleep-away camps). Such classifications might have helped to pull apart family envi- ronmental and family genetic influences.

None of the studies reviewed here was free of all methodologic difficulties, but in general the results do seem to indicate that there are significant food preference simi- larities within families. In future studies a greater attempt should be made to deter- mine if similarities are more likely to be

seen with certain types of foods and if pref- erences for different foods can be related to already known genetic influences on taste preferences, such as the genetically based preferences for salt and sweet.’.* In addition, more efforts need to be made to separate environmental and genetic factors and to delineate family and cultural envi- ronmental influences. A few of the studies reviewed here compared child-parent and child-other child’s parent correlation^,^^^.^ a technique that is useful for separating fam- ily from cultural influences.

Another way to investigate family influ- ences on food preferences is to examine the food preferences of children and their parents when the children are young, and then reexamine the parents and children as the children grow older. It would be possi- ble in a longitudinal study to evaluate the effects of peer influences on food prefer- ences.

The best way to separate genetic and en- vironmental determinants of food prefer- ences would be to conduct twin and adop- tion studies of food preferences. If pairs of identical twins are more similar in their food preferences than are pairs of same- sex fraternal twins, and if children adopted when they were young have food prefer- ences more similar to their biologic parents than to their adoptive parents, that would be very strong evidence that genes play a significant role in the origins of food pref- erences. Unfortunately this type of re- search, while yielding the strongest evi- dence, is also the most difficult to perform.

Future research will undoubtedly employ many of these techniques. The results will help us predict and control food prefer- ences to a much greater extent than is now done.

1. Taste and Development. JM Weiffenbach, Editor. US Department of Health, Education, and Welfare, Bethesda, MD, 1977

2. D. Denton: The Hunger for Salt. Springer- Verlag, New York, NY, 1982

3. JV Burt and AA Hertzler: Parental Influence on the Child’s Food Preference. J Nutr Educ

4. P Pliner and ML Pelchat: Similarities in 10: 127-128, 1978

136 NWRlllON REVIEWSIVOL 45, NO 5IMAY 1987

Food Preferences between Children and Their Siblings and Parents. Appetite 7:

5. LL Birch: The Relationship between Chil- dren’s Food Preferences and Those of Their Parents. J Nutr Educ 12: 14-1 8, 1980

6. G Weidner, S Archer, B Healy, and JD Matar- azzo: Family Consumption of Low-Fat

333-342, 1986

Foods: Stated Preference versus Actual Consumption. J Appl Soc Psycho1 15:

7. P Pliner: Family Resemblance in Food Pref- erences. J Nutr Educ 15: 137-140, 1983

8. P Rozin, A Fallon, and R Mandell: Family Re- semblance in Attitudes to Foods. Dev Psy-

773-779, 1985

cho/ 20: 309-31 4, 1984

LASTING BENEFITS OF SHORT PERIODS OF FLUORIDE INGESTION

Short periods (1 to 6 years) of fluoride ingestion result in lasting reductions in dental caries incidence. These benefits have been observed both for

community and for school fluoridation programs.

Key Words: fluoride ingestion, dental caries in- cidence, community water fluoridation, school water fluoridation. fluoride tablets

When dental investigators are searching for an appropriate community in which to conduct a clinical trial, they understand- ably become concerned about the fluoride status of the individuals in the community. In areas where water fluoridation has been practiced for several years, the children have a substantially lower lifetime caries experience than in similar communities where the water supply contains appreci- ably less than the optimal amount of fluo- ride. A young population group with a high annual dental caries incidence is likely to be more suitable for many types of inter- vention trials because a high number of new carious lesions can be expected among the controls and an effective treat- ment will be more readily apparent.

Burt et all noted that selection of a study site is often made on the basis of whether a community does or does not have water fluoridation. It has not been generally con- sidered whether some children in a com- munity without water fluoridation have had a partial exposure to fluoride during a pe- riod of residence elsewhere. Would chil- dren who have lived for a few years in a

community with optimal water fluoride have detectably different caries experi- ences than the children who have lived continuously in low-fluoride communities? In other words, is a short period of optimal fluoride exposure able to give a lasting benefit with regard to new carious lesions? Burt et all also investigated whether differ- ent caries experiences between the two groups would be reflected in the propor- tions of Streptococcus mutans in plaque removed from the occlusal fissures.

Baseline caries examinations were made on 495 children in grades 1 and 2, ages 6 and 7 years, in Coldwater, Michigan, where the water naturally contains only 0.2 ppm fluoride. Reexaminations were made an- nually for 3 years. Plaque samples were collected at each examination and evalu- ated for Streptococcus mutans. After 3 years, 319 children were still available for evaluation. Of these, 66 percent had lived all of their lives in Coldwater; an additional 13 percent had lived part of their lives in other nonfluoridated communities. The re- maining 21 percent had lived in a fluori- dated area for less than 1 to 6 years. The latter group was too small to divide further by length of residence in a fluoride commu- nity. The mean values for decayed, missing, and filled surfaces in permanent teeth

NUTRITION REVIEWSIVOL 45, NO 5lMAY 1987 137