Methodological issues in food surveys

Excerpt

In our 4-day food survey of Belgian 6- to 36-month-old toddlers, we observed an average energy intake exceeding the national reference values in two-thirds [1]. Alexy and Hilbig suggested that this finding might be explained rather by methodological issues (either in collecting the data or in the way the reference values were constructed) than by actual excessive intakes, since the mean weight for age z scores in our cohort was within normal ranges. It is, however, important to consider that our cohort study does not allow drawing any conclusions regarding causality between the nutritional and anthropometric data. One could argue that the expected increase in body weight due to the excessive intake was compensated by an increased physical activity. Furthermore, the resulting weight gain of the observed excessive energy intake might occur in the following months. Due to the lack of physical activity scores in our cohort, there is no way of knowing how active these children were. And even though our study data provide insight into how well recommendations are followed, it would be a step too far to directly infer new guidelines from it. In the revision of the nutritional recommendations, institutions like the WHO and EFSA have moved away from using observed intakes for their guidelines and started using a factorial method [2, 3]. We do agree with the statement of Alexy and Hilbig that only a small number of infants were used to determine the energy deposition using doubly labeled water technique. Regardless, recommending a restrictive eating pattern in this young age group from our findings would indeed not be the appropriate next step, as young children seem perfectly able to self-regulate their food intake. It is, however, well known that already at the stage of bottle feeding, mothers can have the tendency to overrule satiety signals of their babies, with the risk of over-feeding [4]. That is why we advocated an actual intervention study in our discussion, in which it would be especially interesting to investigate the effect of a lowered protein intake. This would take place in controlled circumstances and would allow us to draw conclusions regarding causality. …