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Validation Information: FFQ (Inulin & Oligofructose)

Dunn 2011

Validation of a food frequency questionnaire to measure intakes of inulin and oligofructose

Background and objectives: Inulin and oligofructose are prebiotic carbohydrates associated with numerous health benefits. The aim of this study was to accurately measure inulin and oligofructose intakes and to develop and validate a food frequency questionnaire (FFQ).

Subjects and methods: A 7-d semi-weighed food diary (FD) was used to measure intakes in 66 healthy subjects. A 23-item FFQ was developed to measure short-term inulin and oligofructose intakes over the same 7 days and was completed twice on 2 separate days.

Results: There were no significant differences in inulin intake (4.0±1.3 vs 4.0±1.4 g/d, P = 0.646) or oligofructose intake (3.8±1.2 vs 3.8±1.3 g/d, P = 0.864) when measured using the 7-d FD or the FFQ. Bland-Altman analysis demonstrated low mean differences between the FD and FFQ in measuring intakes of inulin (-0.09 g/d) and oligofructose (-0.03 g/d). The FFQ categorised 89% of subjects into the same or adjacent tertiles of intakes as the 7-d FD. For the majority of food items, kappa values indicated ‘substantial’ or ‘almost perfect’ agreement for assignment of ‘portion size’ and ‘frequency of consumption’ between the FFQs completed on separate days.

Conclusions: The FFQ is a valid and reliable method for measuring short-term inulin and oligofructose intakes for use in dietary surveys and clinical trials.

Web Link

Validation Information

Year of Publication

Tool Information

Dietary Exposure Measured
Tool Type
Food Frequency Questionnaire
Timeframe Tool Measures info
1 Week
Portion Size Measures info
Typical portion sizes which were described as household measures were requested for each food item (small,medium and large). The weight of each was taken from standard food portion size tables (Crawley, 1988).
Reporting Method info
Format info
Supplements Measured
Not Reported
Administration Method info

Study Information

Study Location
London, England
Associated Nutrient Database
The FFQ used an in-house programme spreadsheet in Microsoft Excel. Information on how inulin and oligofructose was calculated from the food diary can be found in the publication.
Comparator Validated Against
Weighed Food Diary


Sample Size
Age of Population

Range: 18-50 years

Mean(SD): 31.16(7.5) years

Other Notable Characteristics
Healthy students and staff at King's College London

Total number of nutrients validated: 0 info

Not all of the nutrients validated in the validation studies are included in the table below, as statistical data was only selected to be displayed for a number of nutrients, this included:

  • Energy
  • Fat
  • Saturated Fat
  • Mono-unsaturated Fat
  • Poly-unsaturated Fat
  • Carbohydrates
  • Protein
  • Sugar
  • Non‐starch polysaccharides(NSP)
  • Sodium
  • Calcium
  • Iron
  • Zinc
  • Retinol
  • Folate
  • Folic Acid
  • Vitamin B12
  • Vitamin C
  • Fruit & Vegetables
  • Urinary Nitrogen

To find information on the other validated nutrients please read the validation study.

  • Macronutrients: 0
  • Micronutrients: 0
Comparator Lifestage Sex Nutrient Measured info Mean Difference Standard Deviation info Correlation Coefficient info Cohen's Kappa Coefficient Percentage Agreement Percentage Agreement Categories info Lower Limits of Agreement Upper Limits of Agreement
Weighed Food Diary Adults Both

Some results have been calculated using statistical techniques based on the published data.

For further information on statistical terms click on Statistical tests used in validation studies

All correlations coefficients in the table are unadjusted unless stated otherwise. For adjusted correlation coefficients and other statistical methods used in the study e.g. paired t-tests, please read the validation articles.

  • # Adjusted
  • † Energy adjusted.
  • ‡ For loge-transformed, energy-adjusted nutrient intakes.
  • ^ Adjacent included.
  • ᵟ Participants provided identical responses.
  • (w) = Weighted.

Dunn S, Datta A, Kallis S, Law E, Myers CE, Whelan K. Validation of a food frequency questionnaire to measure intakes of inulin and oligofructose. European journal of clinical nutrition. 2011 Mar 1;65(3):402-8.