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Citation:
von Ruesten A, Illner AK, Buijsse B, Heidemann C, Boeing H. Adherence to recommendations of the German food pyramid and risk of chronic diseases: results from the EPIC-Potsdam study. Eur J Clin Nutr. 2010 Nov; 64(11): 1,251-1,259.
Study Design:
Prospective Cohort Study
Class:
B - Click here for explanation of classification scheme.
POSITIVE: See Research Design and Implementation Criteria Checklist below.
Research Purpose:

To develop a comprehensive diet quality index to assess the adherence to the German food pyramid recommendations and investigate the association of this index to the risk of chronic diseases.

Inclusion Criteria:

Participants of the EPIC-Potsdam study with complete baseline and follow-up data on:

  • Diet
  • Lifestyle habits
  • Medical history
  • Anthropometric measurements.
Exclusion Criteria:

Participants who:

  • Reported prevalent T2D, CVD or cancer at baseline
  • Withheld information on diet and lifestyle variables
  • Missed follow-up time
  • Reported implausibly high or low energy intake (less than 800kcal or more than 6,000kcal per day).
Description of Study Protocol:

Study Description

  • The EPIC-Potsdam study is a prospective cohort study among 27,548 participants from the general population of Potsdam, Germany, who were 35 to 65 years of age at recruitment
  • Baseline measurements consisted of self-administered food frequency questionnaire, a computer-guided interview on lifestyle habits and medical history, and anthropometric measurements performed by trained staff. Every two to three years, participants received a mailed follow-up questionnaire to assess incident diseases.

Study Duration

Participants were recruited between 1994 and 1998. Average length of follow-up was reported in person-years (183,740) or 7.8 years.

Location

Potsdam, Germany.

Data Collection Summary:

Dietary Assessment Method

  • Semi-quantitative food frequency questionnaire
  • Portion size and frequency of intake of 148 foods consumed during the preceding 12 months
  • Frequency scale was never to five times per day and portion sizes estimated using photographs or standard household measures
  • Reproducibility and validity of this instrument has been previously established (Boeing et al, 1997; Bohlscheid-Thomas et al, 1997a, b; Kroke et al, 1999).

Dietary index/Score Used

German Food Pyramid Index and Score:

  • GFPI is based on eight out of nine food groups for which the German FP gives recommended intakes:
    • Non-alcoholic beverages
    • Vegetables
    • Fruits
    • Cereals
    • Dairy products
    • Meat, sausages, fish or eggs
    • Added fat and oil
    • Sweets and snacks.
  • A computerized dietary assessment tool disaggregated mixed foods into their ingredients, and single foods were assigned to the appropriate group
  • Frequency of consumed servings was calculated by dividing the total amount of estimated food group intake from the FFQ by serving size.

Index/score Components

  • Provide a brief description of the factors included in the index/score
  • These eight sub-components together comprise the GFPI score, ranging from zero (no compliance with recommended intake) to 10 (perfect conformity with recommendations)
  • The component (food group) scores were calculated and added up to obtain a total score, which could range from zero to 110 (80 points plus 30 extra points)
  • Higher scores reflect greater adherence to the recommendations.

Outcomes Measured

  • Myocardial infarction
  • Stroke
  • Diabetes
  • Cancer.

Methods of Outcome Assessment

  • Information about incident diseases was obtained using all available sources including self-reports on new medical diagnosis, medication use or reasons for reported change in diet in the follow-up questionnaires
  • Potential cases were verified by a physician, medical records and cancer registries and diseases were coded based on the ICD-10 for myocardial infarction, stroke, diabetes and cancer.
Description of Actual Data Sample:
  • Sample size: 23,531 (9,098 men and 14,433 women) out of 27,548 were included
  • Age: Age was reported as means within quintiles of diet quality by gender:
    • One (men): 50.1±7.6
    • Three (men): 51.3±8.0
    • Five (men): 53.2±8.3
    • One (women): 46.5±8.8
    • Three (women): 47.7±9.0
    • Five (women): 49.7±9.6.
  • Gender: 61% female
  • Baseline health status: Healthy
  • Baseline distribution of dietary patterns: Quintiles of dietary scores:
    • N=9,098 total men
      • Quintile One (men): 41.2 (median range was 23.5 to 44.6)
      • Quintile Three (men): 51.1 (49.1 to 53.1)
      • Quintile Five (men): 62.0 (58.0 to 92.1).
    • N=14,433 total women:
      • Quintile One (women): 41.2 (median range was 23.5 to 44.6)
      • Quintile Three (women): 51.1 (49.1 to 53.1)
      • Quintile Five (women): 62.0 (58.0 to 92.1).
Summary of Results:
  • Results were reported in hazard ratios related to CVD, T2DM and cancer
  • Strong inverse relationship between GFPI scores and risk of CVD was observed in men but not women. The significant inverse association in men persisted after controlling for further risk factors, including BMI. Men in the highest quintile had a 44% lower risk of CVD compared with those in the lowest quintile; the non-significant association in women was independent of post-menopausal status and hormone use.
  • In men and women, GFPI scores were inversely related with T2DM in models adjusted for age, education, lifestyle, history of dyslipidemia and hypertension. Accounting for BMI attenuated these associations.
  • For cancer, no consistent trends were found.
    • Men HR, 1.16; 95% CI: 0.83 to 1.62; P=0.40
    • Women HR, 0.79; 95% CI: 0.58 to 1.08; P=0.14.

 

 

Confounders
Medication/ Supplement Use Physical Activity Baseline Weight Status Sex Age Smoking Others
Vitamin supplementation x x   x x Education, total energy intake, history of hypertension, alcohol intake

 

 

 

 

Author Conclusion:

Adherence to the recommendations of the German Food Guide Pyramid in the current form does not have much impact on disease risk. In the largest prospective study in Germany, the score values related inversely to incidence of CVD in men but not women. Although inverse associations were seen for T2DM risk in both men and women, these were largely explained by lower BMI in those with higher GFPI scores. Cancer risk was not related to GFPI scores.

Strengths

  • One advantage of the GFPI is that adherence to the German food pyramid is expressed in one figure. The single component scores were calculated proportional to intake instead of using simple cut-off values with scores of zero and one.
  • A further strength of the GFPI is the integration of a score deduction to account for over-consumption of energy-rich food and extra points for beneficial food groups like beverages, fruits and vegetables.

Limitations

  • Self-administered FFQs
  • Because women and persons with overweight or obesity appear to under-report their food intake, in particular foods rich in fat and sugar (Heitmann and Lissner, 1996; Voss et al, 1997; Yannakoulia et al, 2007), we can not exclude that selective under-reporting is responsible for this association.
Reviewer Comments:

Research Design and Implementation 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 nutrition or dietetics practice?
Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies)
N/A
 
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?
Yes
  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?
Yes
  2.4. Were the subjects/patients a representative sample of the relevant population?
Yes
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?
Yes
  3.3. Were concurrent controls used? (Concurrent preferred over historical controls.)
No
  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 or cross-sectional 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. Criterion may not be applicable in some cross-sectional studies.)
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?
???
  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.)
???
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?
???
  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?
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