AWM: Nutrition Education (2006)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To see if reduced fat foods were genuinely less appealing, to test the hypothesis that any negative effect of a low fat label would be reduced in a genuinely high fat food, and to see if the health- and food-related attitudinal and behavioral characteristics of participants moderated any effects labels had on hedonic rating. 
Inclusion Criteria:
None specifically mentioned.
Exclusion Criteria:
An expressed refusal to eat one of the experimental foods.
Description of Study Protocol:

Recruitment

Recruited from a volunteer subject panel at Institute of Psychiatry and by individual solicitation.

Design

Nonrandomized Clinical Trial.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Participants tasted and rated 3 cheeses, 3 yogurts, and 3 koerrtas on hedonic, intention and sensory dimensions, labelled as either Higher than normal fat content, Normal, or Lower, while actual fat content was constant.

Statistical Analysis

Pearson r correlations, paired t tests, one-way ANOVAs and repeated measures MANOVAs were performed.  Wilks' was used as the multivariate test of significance.  The sources of variance for these analyses were label, food and label x food.  Only the results for the 2 main dependent variables are presented.

Data Collection Summary:

Timing of Measurements

Participants tasted and rated 3 cheeses, 3 yogurts, 3 koerrtas.

Dependent Variables

  • Pleasantness rated on numeric 9 point scale
  • Likelihood of buying on 7 point scale

Independent Variables

  • Each sample labelled as Higher than normal fat content, Normal or Lower, while actual fat was constant.  Cheese, yogurt and koerrta selected from pilot using 30 members from public.  Subjects instructed not to eat for 1 1/2 hours prior to experiment.
  • Dietary behavior assessed using Food Habits Questionnaire and a score derived from consumption of 12 dairy products, together gave Cronbach alpha = 0.65 
  • Dutch Eating Behaviors Questionnaire for dietary restraint score
  • Health as a Value Questionnaire
  • Food Neophobia Scale
  • Eating Motivation Questionnaire

Control Variables

 

Description of Actual Data Sample:

Initial N: 36 normal-weight subjects, 18 men, 18 women

Attrition (final N):  36; 2 had dropped out due to error and awareness, but were replaced.

Age:  Mean age 28 +/- 8.1 years, range 18 - 53 

Ethnicity:  Not mentioned

Other relevant demographics:  Not mentioned

Anthropometrics 

Location: London

 

Summary of Results:

Other Findings

The presence of significant and predictable label effects on dimensions such as perceived healthiness and amount of fat demonstrated the efficacy of the manipulation.

The Lower labelled foods were rated slightly less pleasant than the Normal but there was no interaction with type of food, t(34) = -2.28, p = 0.029.

However, there was an interaction with food type for rated likelihood of buying:  participants were more likely to buy the Lower labelled yogurt than the Normal [t(35) = 2.53, p = 0.016] or Higher yogurts [t(35) = 3.42, p = 0.002].

Participant characteristics were important moderators of the effect of the dietary fat-related labels.

Those participants who reported a greater perceived influence of general health concerns on food choice, for example, rated the Higher fat labelled foods as less pleasant [F(2,31) = 9.13, p = 0.001] and tended to be less likely to buy the Higher labelled yogurts and cheeses than those who reported a lower perceived influence [F(4,31) = 4.46, p = 0.006]. 

Author Conclusion:
The present study demonstrated a weak hedonic effect of labelling foods as lower fat, being rated less pleasant than those thought to be normal fat.  Varying the food type and using more specific labels did not have the predicted effects on hedonic ratings although there were effects on rated likelihood of buying.  Participants having different characteristics responded to the labels in quite different ways, however.  It is therefore difficult to draw any overall conclusions about how low fat foods are perceived by the general population from the main effects of the few published studies of varied design.  Nevertheless, there is clearly a proportion of consumers who expect not to like reduced fat or fat-free foods.  This proportion may decline as such foods become more acceptable through changes in the methods of fat substitution.
Funding Source:
Government: Biotechnology and Biological Sciences Research Council (UK)
Reviewer Comments:
Measures tested for reliability.
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? ???
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? ???
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
3. Were study groups comparable? ???
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) ???
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? ???
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? No
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? N/A
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes