Tailoring dietary feedback to reduce fat intake: an intervention at the family level

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1 HEALTH EDUCATION RESEARCH Vol.15 no Theory & Practice Pages Tailoring dietary feedback to reduce fat intake: an intervention at the family level Ilse De Bourdeaudhuij and Johannes Brug 1 Abstract stronger awareness of personal fat intake and awareness of fat intake of family members. In this study, we wished to investigate whether Tailored advice has the potential to communicate the use of tailored nutrition education letters the personal need to change. As differences in addressed to each family member simultaneously fat reduction between family members receiving at home could serve as a valuable strategy general or tailored nutrition education letters for nutrition education. Family quartets (both were smaller than expected, future research will parents and two adolescents, all healthy have to prove that family-based tailored interventions individuals) were chosen to be the units of are more effective than standardized intervention. The first aim of our study was to interventions and interventions focusing on a investigate the impact of tailored versus standardized nutrition education on fat intake and on psychosocial determinants of fat intake in families, using a randomized dietary feedback study. Our second aim was to study the differential effect of the tailored nutrition education on different family members. Analyses were con- single person. It also needs to be clarified why mothers in particular benefit from tailored feedback. Introduction There is a consensus that dietary change interventions ducted among 18 experimental families (n 72) are a necessary component of health promotion and 17 control families (n 68). The tailored programmes to prevent cardiovascular diseases and intervention was more effective than the nontailored cancer (Glanz, 1988; Kris-Etherton et al., 1988; intervention in reducing total and satur- Heimendinger et al., 1990; Potter et al., 1990; World ated fat intake when all the family members were Health Organization, 1990; Gordon et al., 1991). included (F 4.0, P < 0.05 and F 5.9, P < Within a healthy diet, reducing fat intake and 0.05). However, follow-up analyses revealed that increasing fruit/vegetable consumption play an only mothers benefit from the tailored interven- important role. Individualized, or tailored, nutrition tion (F 6.4, P < 0.05 and F 10.2, P < 0.005). education interventions have been shown to be For fathers and adolescents, both interventions effective in inducing dietary change (Brug et al., resulted in a significant decrease in fat scores. 1996, 1999). The present study investigates the Furthermore, tailored feedback resulted in impact of tailored nutrition education materials at the family level. First, the rationale for family-based tailoring will be briefly described, then the evidence University of Ghent, Faculty of Medicine and Health for the effectiveness of tailoring health education is Sciences, Department of Movement and Sport Science, reviewed, after which the design, methods and Watersportlaan 2, 9000 Ghent, Belgium and 1 Department results of the present study will be described and of Health Education and Promotion, Universiteit Maastricht, PO Box 616, 6200 MD Maastricht, discussed. The Netherlands Epidemiological evidence exists for the Oxford University Press

2 I. De Bourdeaudhuij and J. Brug relationship between fat intake and the prevention of Roth and Fonagy, 1996). Interventions are adapted cardiovascular disease. Total (saturated) fat intake or to the individual s diagnostic, behavioral and energy percent from fat or from saturated fat and motivational characteristics. In the field of health hypercholesterolemia have been found to be psychology, tailoring interventions to the indivi- associated with arteriosclerosis and morbidity and dual is specifically used in secondary and mortality related to cardiovascular diseases (Willet, tertiary prevention, e.g. in order to try to help 1994; Ascherio et al., 1996). Dietary guidelines in patients suffering from hypercholesterolemia or most Western countries including Belgium recommend recovering from a heart attack to change their reducing fat intake to 30 35% or less of the activity patterns, food choices or smoking habits energy intake (US Department of Agriculture/US (Butowski and Winder, 1998; Willett, 1998). In Department of Health and Human Services, 1985; primary prevention and health education, efforts Hulshof et al., 1993; Voedingsaanbevelingen voor have been made only recently to tailor interven- België, 1996). Despite the general awareness among tions to individual s characteristics. Because large the population of the risks associated with a highfat numbers of people are often involved in primary diet, the prevalence of high-fat intake is still very prevention, a skip was made from group or high. In Belgium, 60 70% of the adult population individual face-to-face education to written educa- consume more than 35% energy from fat, while only tion. In the past few years, tailoring has been 11 16% meet the guideline of 30% energy from fat used especially in smoking cessation interventions (De Bourdeaudhuij and Van Oost, submitted). In (Strecher, 1999) but also for dietary change Belgium, as in other countries, mean energy (Brug et al., 1996, 1999). The use of powerful percentages of fat between 38 and 40% were found computers which can match answers on a (Kant et al., 1995; De Bourdeaudhuij and Van Oost, questionnaire to specific interventions enables submitted). High-fat intake is prevalent in all age health educators to reach large groups of people in groups, socio-economic groups and in both sexes which the human-guided intervention is combined (Hupkens et al., 1997). Hence, it is not possible to with a maximal cost-effectiveness (Velicer et al., identify specific target groups based on traditional 1993). Recently, eight studies on tailored nutrition segmentation variables. As a consequence, it is interventions for primary prevention of chronic necessary to focus on large numbers of people in disease have been reviewed (Brug et al., 1999). which five vehicles can be used: schools, work sites, The authors concluded that tailored nutrition community agencies, medical care facilities and interventions were generally more effective and media (Kolbe, 1988). However, most nutrition inter- better appreciated than general nutrition education, vention studies do not report large effects on especially for fat reduction. The authors further behavior change and suggest that maintaining long- argued that personalization of fat reduction term change is difficult to achieve (Hollis et al., education was especially useful, since many 1984; Zimmerman and Connor, 1989; Backett, people are not aware of their high-fat intake. 1992). Moreover, there are many different misconcep- Fat reduction interventions may become more tions about low-fat alternatives to high-fat choices. effective when these interventions are tailored to Until now, tailored nutrition interventions have relevant individual characteristics of the people in only focused on individuals (Brug et al., 1996, the target population and when the family context is 1999). However, it has been argued that dietary taken into account. behaviors are especially well suited to familybased Traditionally, behavior change was the realm interventions because meals often involve of psychologists, mostly experts trained in the the entire family (Nader et al., 1989, 1992). In field of psychopathology. In psychotherapy, the past, family-based interventions were often therapists match their interventions maximally to translated into an intervention directed at the the needs of the client (Velicer et al., 1993; mother. She was assumed to have the strongest 450

3 Tailoring dietary feedback to reduce fat intake impact on the dietary behavior of all family second aim was to study the differential effect of members. Some researchers, however, stressed the the tailored nutrition education on different family importance of the influence exerted by other family members. members, both the husband and the children It was expected that subjects in experimental (Eppright, 1969; Kerr and Charles, 1986; Newson families would appreciate their intervention material and Newson, 1990; Mennell et al., 1992). Several better and that they would experience stronger studies were conducted in Belgium to obtain an subjective effects of the intervention they received. insight into the ability of each family member It was further expected that subjects within the to influence food consumption patterns. Major experimental families would have a stronger implications for nutrition education were that decrease in fat intake levels and an increase in targeting only the gatekeeper (mother) is counter- positive determinants towards fat reduction after productive, that one member of the family is the intervention when compared to subjects in the seldom strong enough to influence family food control families. We further hypothesized that choices and that nutrition education interventions the tailored nutrition education would have equal could be expected to be more successful if several effects on each family member. family members decide to change their eating We believe that this study is of special behavior in a more healthy way at the same time importance in the field of health education research (De Bourdeaudhuij and Van Oost, 1997, 1998a,b; as it may possibly provide us with a feasible De Bourdeaudhuij et al., 1997a,b). From this it and effective strategy for implementing nutrition can be argued that efforts have to be undertaken to education at the family level. construct effective and feasible nutrition education interventions directed at whole families. However, it is clear that developing nutrition education Methods programmes involving entire families is not easy. Sample and procedure Previous efforts experienced significant problems such as high non-attendance rates, drop-out and A random sample of two-parent families with at difficulty with recruitment (Perry et al., 1987; least two adolescents (aged between 12 and 18) Baranowski et al., 1990). In this study, we wished living at home was drawn from Ghent, a mid-sized to investigate whether the use of tailored nutrition town in Belgium. Families were contacted by education letters directed at each family member telephone and asked to come to the laboratory to simultaneously at home could serve as a valuable participate in a study on food choices. Because of strategy for nutrition education. Family quartets the inclusion criterion that four members of each (both parents and two adolescents) were chosen as family had to participate, the response rate was the units of intervention. The first aim of our study low (10%). The main reasons for non-participation was to investigate the impact of tailored versus reported by subjects were (1) organizational standardized nutrition education to reduce fat problems, as we asked for the four family members intake in families, using a randomized dietary to attend the laboratory together at the same time, feedback study. As there are strong indications that and (2) refusal to participate by one or more family health behavior is primarily a result of behavioral members (especially fathers and adolescents). intention, which in turn is predicted by three main Nevertheless, 40 families (n 160) agreed to psychosocial factors, i.e. attitudes, social influences participate and were randomly assigned to an and self-efficacy expectations or perceived experimental or control intervention. At base- behavioral control (De Vries et al., 1988; Ajzen, line, each participant received a questionnaire 1991; Conner and Norman, 1996), differences in designed to obtain information on the psychosocial changes in psychosocial determinants of fat intake determinants of fat intake together with a food- between both conditions were also studied. Our frequency questionnaire to measure energy percent- 451

4 I. De Bourdeaudhuij and J. Brug ages of fat. As all subjects completed the question- to what degree they thought that eating fat is bad naires at the laboratory, with a research assistant or good, unpleasant or pleasant, and nasty or tasty present, we thus checked for the bias often found (three items; Cronbach s α 0.80). Perceived in family research in that several questionnaires social support was measured by asking respondents are filled in by the same person (De Bourdeaudhuij to what degree they expected social support from and Van Oost, 1998a). family members and from friends if they tried to Two weeks later, all members of the families in eat less fat (two items; Cronbach s α 0.79). the experimental condition were mailed nutrition Self-efficacy was measured by asking respondents education letters at their home addresses, tailored how difficult or easy they thought it was and how to personal fat intake levels, motivation to reduce confident they were of being able to eat less fat in fat intake, awareness of personal fat intake, and certain difficult situations (having a lot of work, attitudes and self-efficacy expectations related to being alone, having to buy other products, really fat reduction. Feedback letters were not computer- wanting to) (five items; Cronbach s α 0.83). tailored, but tailored manually. All members of Self-assessed fat intake (awareness) was measured the families in the control condition received by asking respondents to evaluate their fat intake, (identical) general nutrition education letters which and by comparing this intake with people of their were also addressed to them personally. Four weeks age and sex (two items; Cronbach s α 0.79). after the subjects had received their feedback Fat intake of significant others was assessed in letters, they were asked to attend the laboratory the same way as the self-assessment for family again to complete the post-test questionnaires. Two members (two items; Cronbach s α 0.76) and families from the experimental group and three for friends (two items; Cronbach s α 0.66). One families from the control group dropped out, mainly question was included to measure the subjects because all four family members were not willing intentions to eat a low-fat diet. Attitudes were to come to the laboratory a second time. All measured in relation to eating fat, whereas eating analyses were conducted among the 18 experi- less fat was used as target behavior in all the mental families (n 72) and 17 control families other items, except for intentions, where a low- (n 68), representing 87.5% of the subjects who fat diet was used. This inconsistency in item completed the baseline screening. construction may, for example, lead to an over- Questionnaires estimation of positive intentions towards eating a low-fat diet because many people are convinced The measures for the independent variables were that they already eat a low-fat diet. All previous derived from Brug et al. (Brug et al., 1997), based items were measured on seven-point scales. on Operant and Social Learning Theories (Bandura, In the post-test questionnaire the same variables 1986), and on social-psychological theories such were assessed. In addition, the participants were as the Theory of Planned Behavior (Ajzen and asked about their reactions to the nutrition informa- Madden, 1986) including attitudes, social influ- tion letter that they received and whether the ences and self-efficacy expectations. On the basis nutrition information letter had resulted in changes of research on determinants of motivation to reduce in opinions about their diets, in their intentions fat consumption (Brug et al., 1994), awareness of and in their dietary behavior (see Table I for items). personal intake was also included as a determinant. To assess eating patterns, registered dieticians Moreover, awareness of other family members adapted a 56-item food-frequency questionnaire and friends fat intake was included as the present validated in the Netherlands (Feunekes et al., intervention at the family level was supposed to 1993) for our Flemish population. Some minor have a broader impact than an individual interven- changes were made, adding some typical Flemish tion (see Intervention for more information). food. Respondents could choose whether to report Attitudes were assessed by asking respondents the frequency of consumption of each food item 452

5 Tailoring dietary feedback to reduce fat intake Table I. Respondents reactions to the feedback letters; means and t values; percentage of respondents who agreed with the given statements and χ 2 Tailored feedback General feedback t value The nutrition information letter was interesting The nutrition information letter is of personal relevance to me c The nutrition information letter contained a lot of new information c The nutrition information letter was credible a The nutrition information letter was comprehensible Tailored feedback General feedback χ 2 I have read the nutrition information letter completely 97% 71% 16.9 c I have saved the nutrition information letter 90% 74% 5.7 a I have discussed the nutrition information letter with others 80% 46% 18.0 c As a result of the nutrition information letter......i changed my opinion about my diet 69% 32% 18.9 c...i intend to change my diet 62% 31% 13.1 c...i changed my diet 46% 25% 6.6 b Scores at a seven-point scale from 3 (very low) to 3 (very high). a P 0.05; b P 0.01; c P per day, per week or per month with a reference Intervention period of the past 4 weeks. From this food- The intervention was mainly targeted at reducing frequency questionnaire, intake of total fat, fat intake. Subjects in the experimental condition saturated fat, monounsaturated fat and poly- received a feedback letter including messages unsaturated fat was computed in grams and as a based on their answers to the screening questions. percentage of total energy intake. For this purpose, The tailoring procedure developed by Brug et al. a computer program was written by Aben et al. (Brug et al., 1998) was followed and the messages (Aben et al., 1993), in which frequency of con- included in the Brug et al. (Brug et al., 1998) sumption for each food item was first calculated computer program were used. However, in the per week and then multiplied by a weighted fat present study the letters were constructed manually. factor based on the fat content of food items as The original Brug et al. (Brug et al., 1998) comreported in the NEVO tables in the Netherlands puter program was based on a different food- (Stichting Nederlands Voedingsbestand, 1987). frequency questionnaire which is less suitable for Standardized portion sizes were used in computing use among a Flemish population and has not fat scores. The validity and reliability of this been validated among adolescents. No computer adapted food-frequency questionnaire were investi- program was written for the present study since gated in a small sample of students (n 45 for we first wanted to establish the potential of familyvalidity, n 90 for reliability). Pearson s product- based tailoring before making this investment. moment correlation coefficient used to evaluate Respondents received feedback about their fat the linear association between the results of the intake as well as about their attitudes, perceived food frequency questionnaire and a 7-day food support and self-efficacy in relation to fat reduction. diary showed appropriate validity (r 0.78). The feedback messages about fat intake included Further, test retest reliability using an interval of respondents actual fat consumption expressed in 2 weeks showed a Cronbach s α coefficient of percent of energy from fat, a comparison of this 0.83 on total fat intake. percentage with the Flemish recommendations 453

6 I. De Bourdeaudhuij and J. Brug (preferably 30% and not more than 35% energy from fat) and with the mean scores of the other adolescents, mothers or fathers participating in this study. The messages also included the comparison between the actual consumption and the way in which participants rated their own consumption. A figure was included to visualize personal fat intake levels as compared to the recommendation as well as to the mean fat intake of comparable others (adolescents, mothers or fathers). Further messages were included which addressed different important dietary fat sources in the Flemish diet, for which low-fat alternatives to high-fat choices were suggested. Further, for respondents with low self-efficacy expectations, suggestions were given on how to deal with high-risk situations such as the presence of high-fat foods in the home (avoiding such situations by making low-fat shopping lists), being alone (suggestions on low-fat alternatives for meals for one) and lack of time for food preparation (recipes for easy to cook low-fat alternatives). Finally, all subjects who reported a positive inten- tion to reduce their fat intake were advised to convert these plans into direct action in the week(s) to come, preferably in the next week. No attempts were made to stimulate positive family influence, e.g. by including recommendations to share the results with other family members. Subjects in the control condition received a general nutrition education letter (Brug et al., 1998). This letter included information about the importance of a healthy diet, and gave general information about dietary fat reduction, the health risks of a high-fat diet were stressed, the mean population intake (40% energy) was compared with the recommendations (30% energy), and further information was given about reducing fat in milk and dairy products, butter, meat, sauce, snacks, sweets and chocolate. Analyses In order to assess possible response bias, t-tests were carried out to look at differences in mean fat scores between subjects within families who dropped out and subjects who completed the base- line and the post-test questionnaires. χ 2 tests and t-tests were conducted to study differences in family members reactions to the feedback letters for the tailored and the non-tailored groups. Repeated measures MANOVAs were used to test for significant changes over time in fat intake and determinants between the tailored and non-tailored groups. Time was used as a within-subjects vari- able, condition as a between-subjects variable. Results Dropout analysis A significant difference was found between dropouts (mean 16.0%) and the research sample (mean 14.3%) for intake of monounsaturated fats [t(158) 2.29, P 0.05] at baseline, with a higher intake among dropouts. No differences were found for total fat [t(158) 1.14, NS], saturated fat [t(158) 0.15, NS] and polyunsaturated fat [t(158) 0.57, NS]. Participants reactions to the tailored letters Table I shows the respondents reactions to the feedback letters. Both groups rated the information in their feedback letters as interesting and comprehensible, with mean scores between 1 and 2 on a seven-point scale from 3 (very low) to 3 (very high). Respondents in the experimental condition thought that the letters were more personally relevant (mean 0.9 in experimental and mean 0.2 in control condition) and contained more information that was new to them (mean 0.6 in experimental and mean 0.1 in control condition). However, the subjects who received the general feedback reported that they gave more credence to the letters (mean 1.6) than the subjects in the tailored feedback group (mean 1.2). Further, a significant difference of about 15% was found between the two groups in reading and keeping the letter, in favor of the experimental condition. The majority of the subjects in the experimental group discussed the letter with others (80%), compared to only 46% of the subjects in the control group. Finally, 69% of the subjects 454

7 Tailoring dietary feedback to reduce fat intake Table II. Percent energy from fat at baseline and at post-test for tailored and general information groups, and F values showing time, condition and time condition interaction effects Tailored feedback General feedback F value Baseline (%) Post-test (%) Baseline (%) Post-test (%) Time Interaction Condition Total fat all family members b 4.0 b 2.5 mother b 0.0 father b adolescents b Saturated fat all family members c 5.9 b 2.7 mother d 0.0 father b adolescents b Monounsaturated fat all family members b mother b 0.2 father a a adolescents b Polyunsaturated fat all family members mother father adolescents a 0.05 P 0.10; b P 0.05; c P 0.01; d P who received the tailored intervention reported that they changed their opinion about their diet and intended to change their diet in the future, com- pared with 32% in the control group. Differences in reported behavior change are somewhat smaller though still significant, with 46% of the subjects in the tailored feedback condition reporting that they had changed their diet, compared with one- quarter in the general feedback condition. Differences in impact between baseline and post-test for fat intake Table II shows the results of the repeated measures MANOVA for total fat, saturated fat, monounsaturated fat and polyunsaturated fat. The analyses of variance for total fat and saturated fat showed a significant time effect and a significant interaction effect for all family members together. The time effect reports a significant decrease in total and saturated fat scores for both conditions. The significant interaction between time and condition shows that the decrease in energy from total fat and energy from saturated fat in the tailored feedback group was significantly larger in the experimental condition compared to the general feedback group. Tuckey post hoc tests do not reach significance for differences between family members. However, analyzing these effects separately for mothers, fathers and adolescents shows that the significant interaction between time and condition only applies to mothers, which suggests that only mothers benefit from the tailored intervention. This significant interaction effect may be partly due to the mean total fat scores increasing between baseline and post-test for mothers in the control condition. For fathers and adolescents, only significant time effects were found. This means that both the tailored and the general feedback intervention is effective in reducing energy percentages of total and saturated fat in fathers and 455

8 I. De Bourdeaudhuij and J. Brug adolescents. Fat reduction in the experimental condition was also greater for fathers and adolescents, but a lack of sufficient statistical power may have been responsible for the absence of a significant interaction effect. A similar pattern was found for monounsaturated fat, with the exception that no overall significant interaction effect was found between time and condition. No significant effects were found for polyunsaturated fat. Differences in impact of interventions on determinants of fat intake interaction effect was found for self-efficacy. The condition effect found for parents is due to lower baseline self-efficacy scores for parents in the tailored feedback condition. The condition effect found for family perception shows higher scores on family perception of fat intake in the experimental condition. No significant effects were found for social support. Discussion The aim of the present study was to determine whether tailored information would result in a greater reduction in fat intake in families than non- tailored information. The data showed that the tailored intervention was more effective than the non-tailored intervention in reducing total and saturated fat intake when all family members were included. However, follow-up analyses of individual family members revealed that only mothers benefit from the tailored intervention. For fathers and adolescents, both the tailored and non-tailored intervention resulted in a significant decrease in total and saturated fat scores. In a recent review of the literature, Brug et al. (Brug et al., 1999) reported evidence for an additional impact on fat reduction of tailored feedback as compared to general nutrition information. The present study provides evidence that the impact differs between family members. The program evaluation data show that respond- ents who received tailored feedback more often read the letter completely, kept it, discussed it with others and perceived the information to be more personally relevant and new. This is in line with earlier findings on tailored feedback. Better appreciation and use is a prerequisite for a higher impact of these materials. Further, also in line with earlier studies, respondents judged tailored feedback to be less credible, probably because of the discrepancy between their self-assessed fat intake and their actual fat score reported in the letters (Brug et al., 1998). These findings suggest that, as expected (Campbell et al., 1994; Skinner et al., 1994; Brug et al., 1998), our tailored intervention led to more Table III shows the results of the repeated measures MANOVA for the determinants of fat intake included in our study as well as for the different fat intake perception scales. In general, only a few significant effects were found. Significant differences between the tailored and general feedback group (interaction effects) were present for all family members for perceptions of personal fat intake (awareness) and for parents for perceptions of fat intake levels of family members (family perception). The significant inter- action effect shows that subjects who received the tailored intervention evaluated their fat intake as higher at post-test than subjects who did not receive information about their own fat intake. As only 10 subjects (two adolescents, three fathers and five mothers, or 7% of the total population) were told that their fat intake was in agreement with the recommendations, it is a positive result that subjects rate their fat intake higher at post-test, which means that in general subjects were more aware of their own fat intake. A significant interaction effect for the perception of friends fat intake was only found for adolescents. A significant time effect was found for intention in relation to dietary change. Further, a significant interaction effect was found for attitudes towards fat intake, but in the opposite direction. Subjects, but especially parents, in the tailored feedback group show more positive attitudes towards eating fat over time (or less positive attitudes towards the target behavior), in contrast to parents in the general feedback group who report an increase in negative attitudes towards eating fat. No significant 456

9 Tailoring dietary feedback to reduce fat intake Table III. Mean determinant scores at baseline and at post-test for tailored and general information groups, and F values showing time, condition and time condition interaction effects Tailored feedback General feedback F value Baseline (%) Post-test (%) Baseline (%) Post-test (%) Time Interaction Condition Attitude all family members b 0.3 parents b 0.0 adolescents a Self-efficacy all family members parents b adolescents a Social support all family members parents adolescents Awareness all family members c 8.1 d parents b 5.1 b adolescents b 3.6 a Family perception all family members b 8.1 d 19.4 d parents d 7.0 c 13.1 d adolescents c Friends perception all family members parents adolescents b 0.0 Intention all family members b a parents b adolescents a Means are scores at a seven-point scale from (1) negative to (7) positive. a 0.05 P 0.10; b P 0.05; c P 0.01; d P attention, involvement and cognitive processing among mothers may have several explanations. than the non-tailored intervention. First, mothers often have a special position within Tailored feedback resulted in stronger awareness the family unit with regard to food. Mothers are of personal fat intake and of fat intake of family often seen as gatekeepers controlling the food, members. Since awareness of personal risk being responsible for menu-planning, shopping and behavior has been identified as an important prerequisite cooking (Sallis and Nader, 1988; Pill and Parry, for behavior change motivation 1989). Previous studies found that mothers are (Weinstein, 1988), we consider that the tailoring highly motivated to eat less fat, they have the effect on awareness also points to the conclusion intention to cook and eat a low-fat diet, they have that family-based tailored fat feedback is superior most knowledge about the fat content of foods, to general information about fat reduction. they have most positive attitudes, but they are not The fact that a higher tailoring impact was found able to succeed in changing their children s and 457

10 I. De Bourdeaudhuij and J. Brug husband s food habits on their own (Backett, 1992; might have a powerful effect in changing food Andersen et al., 1995; De Bourdeaudhuij and Van habits. Including family-related messages in the Oost, 1998b). A recent study indeed showed that tailored feedback letters could possibly influence tailored fat feedback is especially effective among these family interactions around food. Depending people who are already motivated to change (Brug on the answers family members give to familyrelated and Van Assema, 1999). questionnaires, guidelines could be given, Secondly, the general nutrition education letter e.g. to establish clear food rules within the family used in our research also included a large amount of (e.g. French fries once a week, chocolate only at information on fat content, fat standards, mean the weekend, etc.), to make shopping lists with all population intake and health risks, and provided family members including at least 50% low-fat subjects with low-fat alternatives to high-fat foods, to make agreements that each family food choices. Moreover, these general information member may choose a low-fat dish and that every- letters were addressed to the family members body would eat at least a part of it without personally. It could be that the difference between complaining, etc. We are aware that including the two interventions was not large enough for these family components in nutrition education subjects with less interest in and less knowledge will be very difficult, although we believe that this of nutrition at baseline (i.e. the fathers and adoles- might be a way to improve family-based tailored cents in the sample). diet feedback in the future. Previous studies showed the potential of multiple Only a few significant effects were found on tailored interventions. In these interventions subjects attitudes, perceived social influences and self- receive more than one tailored letter in which efficacy expectations towards a change in fat intake further recommendations for behavior change are between and within study conditions. This may made within a time span of one to several months. seem surprising as it is generally accepted that Even if the letters in the multiple tailored condition attitudes, social influences and self-efficacy are contained roughly the same information as the strong predictors of behavior and intention (De letters in the single tailoring condition, it was Vries et al., 1988). Part of this lack of effect may shown for nutrition as well as for other health have been caused by the way the determinants behavior that the effect of multiple tailoring were assessed in the questionnaire. Self-efficacy, exceeded that of single tailored feedback letters for example, was questioned in relation to being (Brug et al., 1998; Dijkstra et al., 1999). It may able to eat less fat. If the intervention helped to be possible that multiple tailoring is needed to increase self-efficacy, which in turn resulted in a show an additional effect of tailoring on top lower fat intake at post-test, the perceived ability of general nutrition information for fathers and to further decrease fat intake at post-test could adolescents. Another possibility is that the tailoring indeed be as low as the baseline level. Nevertheless, procedure must be made more comprehensive and the intention to eat a low-fat diet had increased in detailed, focusing especially on family determinants the tailored as well as the non-tailored condition. of fat intake next to the individual determinants This suggests that our intervention succeeded in included in the present study. In previous research decreasing fat intake and in increasing the intention we found that general family characteristics such to eat a low-fat diet without affecting the determinants as family cohesion and adaptability, as well as of intention and behavior. This is not in line more specific family interactions concerning food with the presumed uni-linearity of social cognitive choices such as decision-making, communication models such as the Theory of Planned Behavior and establishing food rules, have an important (Ajzen and Madden, 1986). We would expect that impact on health behavior and more specifically determinants change first, followed by changes in on food choice (De Bourdeaudhuij and Van Oost, intention and behavior. In the past, numerous 1998a,b). Modifying these family interactions studies supported the Theory of Planned Behavior 458

11 Tailoring dietary feedback to reduce fat intake responsible for the lack of significant interaction effects in fathers and adolescents. The present study only investigated the short-term impact of the interventions. It therefore remains uncertain whether the effects found were sustained in the longer run. In the method section, an inconsistency in item construction was reported, in which attitudes were measured towards eating fat, whereas eating less fat was used as target behavior in all other items, except for intentions where a low- fat diet was used. This inconsistency may, for example, lead to an overestimation of positive intentions towards eating a low-fat diet because many people are convinced they already eat a low-fat diet. This inconsistency could have been prevented. A further limitation of the present study is in the use of self-reports to assess tailoring effects (Brug et al., 1999). More objective criteria such as cholesterol levels or other blood parameters would give more verifiable results. Further, the present study did not provide information about possible additional effects of family-based tailoring to individually tailored fat feedback. Finally, it has to be noted that the total fat intake at baseline for the general feedback condition was substantially less than the total fat intake at baseline for the tailored feedback condition and is even less than the fat intake at post-test for the tailored feedback condition. As this difference was not significant, baseline fat intake levels were not included as a covariate in the analyses. However, we are aware that the effectiveness of tailored or standardized nutrition education is possibly dependent upon baseline fat intake level, which may have affected the results. Despite these limitations, this study has several implications for nutrition education practice and research. An intervention aimed at fat reduction in which four family members simultaneously receive a single nutrition education letter at home has shown an impact on fat intake. However, differences in fat reduction between family members receiving general or tailored nutrition education letters were smaller than expected and only valid for mothers. It is possible that the family effect (several family members at a time) is stronger than for food choice and dietary behavior, although mostly using cross-sectional data (Conner and Norman, 1996). Some authors argue that determinants are only rational considerations after behavior has occurred or changed instead of causal factors determining behavior (Bennett and Murphy, 1997). This may be one explanation for the results of the present study. Another explanation may lie in the fact that previous studies revealed that large proportions of populations have misconceptions about personal dietary intake levels (Lloyd et al., 1993; Brug et al., 1997; Lechner et al., 1998). It could be argued that this misconception of personal fat intake is important in several ways. First, people who think they already eat a low-fat diet will not make efforts to decrease their fat intake and they will consider nutrition education interventions not to be applicable to them. Secondly, it has been argued that among subjects who are unrealistic about their fat intake levels, determinants such as attitudes, social influences and self-efficacy are not associated with fat intake because these determinants reflect what people think they eat and not what they actually eat (Brug et al., 1994; Lechner et al., 1998). This could possibly be an additional explanation for the lack of intervention effects on determinants of fat intake we found in the present study. There are several important limitations to note in interpreting this study. First, the response rate was low and it therefore remains uncertain whether the results can be generalized to the Belgian population of families as a whole. However, reported fat scores and intentions to change were comparable with population means. A selection bias still remains possible favoring families, e.g. with specific family interaction patterns. Secondly, the total sample size is low, mainly due to the difficulties in recruitment and to the only partly computerized tailoring procedure we used. In the future, the use of a completely computer-generated procedure will make it possible to study larger samples and to include comprehensive and detailed tailoring. With larger samples, analyses may also be executed at the family level, e.g. using a multilevel approach. The sample size might also be 459

12 I. De Bourdeaudhuij and J. Brug the tailoring effect. However, it was not within voedselfrequentievragenlijst naar energie en vet. GGD regio Geldrop-Valkenswaard, GGD Eindhoven en Vakgroep the scope of this study to investigate the difference Humane Voeding, Landbouwuniversiteit Wageningen, The in impact between a family-based and individual- Netherlands. based intervention. Further research is needed, Ajzen, I. (1991) The theory of planned behaviour. Organizational Behaviour and Human Decision Processes, including both conditions: tailoring versus stand- 50, ardized nutrition education directed to a single Ajzen, I. and Madden, T. J. (1986) Prediction of goal-directed family member versus more than one family behaviour: attitudes, intentions, and perceived behavioural control. Journal of Experimental Social Psychology, 22, member. Further research also has to clarify why mothers benefit from tailored feedback. In the Anderson, A., Milburn, K. and Lean, M. (1995) Food and future, it remains to be proven that tailored inter- nutrition: helping the consumer understand. In Marshall, D. ventions at the family level are more effective than (ed.), Food Choice and the Consumer. Chapman & Hall, London, p standardized interventions and than interventions Ascherio, A., Rimm, E., Giovannucci, E., Spiegelman, D., focusing on a single person. If few differences Stampfer, M. and Willett, W. (1996) Dietary fat and risk of remain between the two methods and the two units coronary heart disease in men: cohort follow-up study in the United States. British Medical Journal, 13 (313), of intervention, the cheaper, more time-efficient Backett, K. C. (1992) The construction of health knowledge and more feasible method would be the one to in middle class families. Health Education Research, 7, go for Bandura, A. (1996) Social Foundations of Thought and Action. However, the tailoring effect on dietary fat A Social Cognitive Theory. Prentice-Hall, Englewood awareness suggests that personal feedback on fat Cliffs, NJ. intake, together with personalized information Baranowski, T., Simons-Morton, B., Hooks, P. and Henske, J. about important fat sources and suggestions on (1990) A center based program for exercise change among Black-American families. Health Education Quarterly, 17, how to cut back on fat, has considerable potential The use of general information focusing on fat Bennett, P. and Murphy, S. (1997) Psychology and Health reduction and/or determinants of fat intake may Promotion. Open University Press, Buckingham. Brug, J. and Van Assema, P. (1999) Differences in use and run the risk of being ineffective, particularly impact of computer-tailored dietary fat-feedback according because many individuals are convinced that the to stage of change and education. Paper presented at the 7th messages do not apply to them personally. They Food Choice Conference, Toronto, June. Brug, J., Van Assema, P., Kok, G., Lenderink, T. and Glanz, wrongly perceive their fat intake and that of their K. (1994) Self-rated dietary fat intake: Association with family members to be low already and therefore objective assessment of fat, psychosocial factors and intention do not perceive any need to change. Tailored advice to change. Journal of Nutrition Education, 26, Brug, J., Steenhuis, I., Van Assema, P. and De Vries, H. has the potential to communicate this personal need (1996) The impact of a computer-tailored nutrition education. to change. Preventive Medicine, 25, Brug, J., Hospers, H. and Kok, G. (1997) Differences in Acknowledgements psychosocial factors and fat consumption between stages of change for fat reduction. Psychology and Health, 12, The authors would like to thank Nathalie Stroobant, Brug, J., Glanz, K., Van Assema, P., Kok, G. and Van Breukelen, Bieke Byttebier and Gert Scheerder for their contriiterative feedback on fat, fruit, and vegetable intake. Health G. (1998) The impact of computer-tailored feedback and bution in data gathering and tailoring feedback Education and Behaviour, 25, 4, letters, and Paulette Van Oost for supervising the Brug, J., Campbell, M. and Van Assema, P. (1999) The project. This study was financially supported by application and impact of computer-generated personalized nutrition education: a review of the literature. Patient the University of Ghent and the Belgian Society Education and Counseling, 36, against Cancer. Butowski, P. and Winder, A. (1998) Usual care dietary practice, achievement and implications for medication in the References management of hypercholesterolaemia. Data from the UK Lipid Clinics Programme. European Heart Journal, 19, Aben, D., Maas, I., van de Waal, M. and Feunekes, G. (1993) Campbell, M., DeVellis, B., Strecher, V., Ammerman, A., De Envet-lijst, ontwikkeling en validering van een korte DeVellis, R. and Sandler, R. (1994) Improving dietary 460

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