Validity And Reproducibility Of A Food Frequency Questionnaire To Assess Dietary Intake In Athletes

Abstract

Optimal nutrition is essential for athletes to maximise performance. Food frequency questionnaires (FFQs) are commonly used to assess habitual dietary intake as they are inexpensive, quick and easy to administer. PURPOSE: To determine the relative validity and reproducibility of an athlete-specific FFQ for assessing food group intake in high performing athletes. METHODS: Athletes (n=66), 16-35 years, from several sports competing at regional level or above completed a 129-item FFQ at baseline (FFQ1) and four weeks later (FFQ2) to assess reproducibility. An estimated 4DFR was completed between these assessments to determine FFQ1 validity. Agreement between methods was assessed using Wilcoxon signed rank tests, Spearman correlation coefficients, cross-classification and the weighted kappa statistic. RESULTS: The FFQ overestimated intake for 17 of 28 food groups compared with the 4DFR (p<0.05). Correlations ranged from 0.11 (processed meats) to 0.78 (tea, coffee & hot chocolate), with a mean of 0.41. Correct classification of food groups into the same tertile ranged from 35.4% (starchy vegetables) to 55.5% (fats & oils). Misclassification into the opposite tertile ranged from 4.6% (legumes) to 15.4% (starchy vegetables; sauces & condiments). The weighted kappa demonstrated fair to moderate (k =0.21-0.60) agreement for most food groups. FFQ1 intake was significantly higher than from FFQ2 for 13 food groups (p<0.05). Reproducibility correlations ranged from 0.49 (potato chips; fats & oils) to 1.00 (tea, coffee & hot chocolate), with a mean of 0.65. Using tertiles, most (20 of 23 assessed) food groups had >50% of participants correctly classified and <10% grossly misclassified, and demonstrated moderate to good agreement (k=0.61-0.8). CONCLUSIONS: The FFQ showed reasonable relative validity and good reproducibility for assessing food group intake in high performance athletes in New Zealand. The FFQ could be used in future research to assess athletes’ food group intake.