Improvement in dietary intake estimates through the combined use of different approaches

Melhora das estimativas de ingestão dietética pela utilização conjunta de duas abordagens

ABSTRACT

Objective  This study aimed to compare dietary intake estimates using two different methodological approaches: use of new portions obtained with the 24-Hour Diet Recall, which was applied in the current study population, and the application of calibration equations, which were estimated using the same 24h-recalls.

Methods  Calibration equations were estimated using linear regression. The medians and confidence intervals of energy and nutrient intakes were assessed using all the approaches. The U Mann Whitney test was applied to verify differences among dietary intakes obtained with the 24 Hour Recall and Food Frequency Questionnaire-based methods. The correlation between different measures was assessed with Spearman coefficient. Weighted Kappa was used to verify the capability of the Food Frequency Questionnaire -based methods to classify individuals in the same intake levels of the 24 Hour Recall.

Results  Nine of the eleven components that were analyzed using the Food Frequency Questionnaire with standard portions and calibrated had medians significantly different from those obtained using the 24 Hour Recall; only the measurements of vitamin E and energy were statistically equal. For the Food Frequency Questionnaire with 24 Hour Recall portions, only the medians of vitamin D and B₁₂ did not significantly differ from the 24 Hour Recall medians. Finally, for the Food Frequency Questionnaire with 24 Hour Recall portions and calibrated, all components, except folate and iron, had medians statistically equal to those obtained using the 24 Hour Recall. Spearman correlation coefficients were higher for the Food Frequency Questionnaire with 24 Hour Recall portions calibrated for all the assessed components, and the values ranged from 0.27 (total fat) to 0.57 (iron). Higher Kappa correlation coefficients were found for the Food Frequency Questionnaire 24 Hour Recall portions calibrated.

Conclusion  Calibrated FFQ with portions estimated from the own target population obtained better estimates of dietary intake, with values considerably more similar to those obtained with the reference method.

Keywords
Food consumption; Nutrition surveys; Statistical analysis