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Adult Weight Management

AWM: Nutrition Education (2006)

Citation:

Neuhouser ML, Kristal AR, Patterson RE.  Use of food nutrition labels is associated with lower fat intake.  J Am Diet Assoc 1999; 99: 45-50, 53.

PubMed ID: 9917731
 
Study Design:
Cross-Sectional Study
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To describe the demographic and diet-related psychosocial correlates of nutrition label use, and examine the relationship between label use and diet.
Inclusion Criteria:
Data are from the Washington State Cancer Risk Behavior Survey, adults aged 18 years and older.
Exclusion Criteria:
None mentioned.
Description of Study Protocol:

Recruitment

Telephone numbers were purchased from GENESYS Sampling System.  Up to 15 call attempts within 1 month were made and an additional 11 attempts 3 months later.  Random-digit dialing from state phone numbers.

Design

Cross-sectional study.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Random-digit dial telephone survey of adults living in Washington state.

Statistical Analysis

Analyses examined associations of demographic characteristics with nutrition label use using the chi-square statistic to test for differences across age, sex and education.  Results were adjusted for sampling probability and to the intercensal estimates of the age-, sex- and county-specific Washington State population.  Associations of diet-related psychosocial factors and health behavior with nutrition label use were examined, usig logistic regression to adjust odds ratios for age, sex and education.  Finally, associations of nutrition label use with fat and fruit and vegetable intake were analyzed using linear regression with the Diet Habits Questionnaire score as the dependent variable and label use as the independent variable.  Covariates included demographic characteristics, BMI, and diet-related psychosocial variables.  We give results of regression models with and without covariates.

Data Collection Summary:

Timing of Measurements

Telephone survey data from Washington State Cancer Risk Behavior Survey, designed to monitor attitudes and behavior related to cancer risk and prevention.  Data collected between September 1995 and September 1996.  Questionnaire assessed nutrition label use, fat-related diet habits, fruit and vegetable consumption, diet-related psychosocial factors, health behavior, and demographic characteristics.

Dependent Variables

  • Diet-related psychosocial factors, health behaviors, and health status captured in survey questions
  • Estimate of dietary fat intake and fruit and vegetable consumption assessed through modified version of the Fat-Related Diet Habits Questionnaire, developed and validated elsewhere
  • Nutrition label use captured in survey questions

Independent Variables

  • Demographic characteristics (age, sex, education, and income)

Control Variables

 

Description of Actual Data Sample:

Initial N: 1450 adults, 59.5% female.

Attrition (final N): 1450 adults.  The conservatively estimated effectiveness rates was 63.5%.

Age:  Mean age was 44.1 +/- 15 years. 

Ethnicity:  90% were white 

Other relevant demographics:  29.3% had a college education 

Anthropometrics (e.g., were groups same or different on important measures)

Location: Washington State

 

Summary of Results:

Other Findings

More than 24% read the nutrition labels at least sometimes, 20.1% read them often, and 35.2% read them usually.

The most frequently read component was grams of fat, followed by calories (total and percent from fat), and cholesterol.

Compared with men, significantly (P < 0.001) more women read information on serving size, calories (total and percent from fat), and grams of fat.  However, slightly more men read information on cholesterol.

Nutrition label use was significantly higher among women, residents younger than 35 years, and residents with more than a high school education.

When controlled for demographic characteristics, the strongest predictors of label use were believing in the importance of eating a low-fat diet, believing in an association between diet and cancer, and being in the maintenance stage of change for adopting a low-fat diet.

Obese respondents were twice as likely to read calories and grams of fat information compared with normal weight respondents.

Label use was significantly associated with lower fat intake, and, after controlling for all demographic, psychological and behavioral variables, explained 6% of the variance in fat intake (P < 0.001).  Label use was not associated with fruit and vegetable consumption. 

Author Conclusion:
Persons successfully limiting their fat intake use nutrition labels, suggesting that the new labels are helpful.  Dietetics professionals can use the results of this study to emphasize to their clients the importance of reading nutrition labels in maintaining a low-fat diet.
Funding Source:
Government: National Cancer Institute (NIH)
Reviewer Comments:
All measures based on self-report.  Data from previous survey related to diet and cancer.  Only certain sections of questionnaire had been validated.
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? ???
  2.2. Were criteria applied equally to all study groups? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  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? Yes
  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.) Yes
  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? N/A
  4.1. Were follow-up methods described and the same for all groups? N/A
  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%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  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? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? Yes
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  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? No
  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? No
  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? ???
  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