4.1. Total and Food Group-Specific Fiber Intake
In this food consumption survey among Belgian preschoolers, the DF intake was on average 13.4 g/d (boys: 13.9 g/d, girls: 12.9 g/d; P < 0.001) and the mean energy-adjusted fiber intake 9.3 g/(1000 kcal*d) (boys: 9.2 g/(1000 kcal*d), girls: 9.3 g/(1000 kcal*d); P = 0.748). It is noteworthy that a higher energy intake seems to correspond with a higher DF intake in boys, possibly due to a higher overall dietary intake. The mean DF intake among Flemish preschool children did not reach the requirements proposed by the BSHC, especially not for the children aged 4–6.5 y, with 70% of the boys and 81% of the girls not meeting the guidelines.
Compared to the recent small-scale Flemish study of Bosscher et al.
(2002) (2–3 y old children: 10 g/d based on 7 d-dietary records, n
= 115), the DF intakes reported in the present study were higher [18
]. As limited data is available on Belgian preschoolers’ fiber intake, additional comparisons were made with preschoolers from other countries with comparable age to evaluate our results. The DF intake among Belgian preschoolers were similar to those among European children in general [17
], and German (10.3–16.2 g/d) [34
] and Italian (11.1–14.6 g/d) [35
] children in particular, all assessed by the same dietary assessment method (food diaries). Conversely, the DF intake among Belgian preschoolers were higher than those reported for Spanish (boys: 11.2 g/d, girls: 10.1 g/d) [36
] and American children (9.1–13.1 g/d) [37
], and lower than those of Swiss children (14.8–16.9 g/d) [38
], all based on two 24-h recalls.
Furthermore, this study aimed to identify the most important contributors to total DF intake among preschoolers. However, differences in dietary assessment and, in particular, classification of food items into food groups, often hamper sound comparisons between different study populations. Nevertheless, in general, the main sources of DF were similar for the current study population and children living in Antwerp [18
]. However, the latter study reported lower contributions for cereals and pastry (6.6%), fruit (15.1%), and potatoes (14.5%). On the other hand, vegetables (13.9%), soup (8.0%), and sugar and candy products (2.1%) contributed more to the total DF intake than in the more general and representative study population of Flemish preschoolers involved in the present study. Additionally, we found that the group of bread and cereals was the most important contributor of DF, as also observed among American children [39
]. Although the contributions of bread and cereals, and vegetables were in line with US reports (29.4% and 11.3%, respectively), potatoes and fruits contributed more to the DF intake of Belgian preschoolers than of American children (11.2% and 13.1%, respectively) [39
]. In comparison to Spanish children [40
], the contributions of bread and cereals, potatoes, and vegetables were lower in Spanish children (11.2%, 4.3%, and 7.9%, respectively) than in ours, while those of fruit and legumes were much higher in Spanish children (25.6% and 20.1%, respectively) than in Belgian children. Finally, the average DF intakes from cereals, fruit, and vegetables were substantially lower in Belgian than German children (4.4–8.0 g/d, 2.8–3.3 g/d, and 2.4–3.0 g/d, respectively) [34
When looking at the food groups that are being under-consumed according to the FBDG [41
] and, taking into account the contributions of these foods to the total fiber intake in these preschoolers, it can be concluded that higher intakes of whole-wheat bread, fruit, and vegetables, could significantly increase the fiber intake and should, therefore, be promoted among preschoolers.
4.2. Associations of Fiber Intake with Socio-Economic Status
To the best of our knowledge, there is no data available on possible associations between DF intake and SES factors among Belgian children. Our results indicate that children of secondary educated mothers have lower DF intake than those of higher educated mothers, whereas children with one parent being employed consumed more DF compared to those with unemployed parents. Similarly, maternal and paternal level of education were related to the food group-specific fiber intake of their children, with lower bread and cereal-, higher potato and grain-, and lower energy-dense, low-nutritious foods-derived fiber intake reported for children of lower secondary educated mothers compared to those of higher educated mothers. On the other hand, higher bread and cereal-, and fruit-derived fiber intake was observed with paternal secondary education as opposed to higher education. Additionally, children with employed parents had higher total DF intakes, but consumed less DF from energy-dense, low-nutritious food than preschoolers with both parents unemployed. In two-parent families, children had higher intake of energy-dense, low-nutritious food-derived fibers than in one-parent families.
Perry et al.
(1988) suggested that parental involvement plays a critical role in promoting children’s health behavior and dietary habits at an early age [42
]. Parental involvement might result in consumption of fiber from high-nutritious foods (vegetables and fruit). In the present study, DF intake, more from high-nutritious foods (vegetables and fruit) and less from energy-dense, low-nutritious foods, were reported for preschoolers of higher educated mothers. Also, evidence showed that children in low SES families were found to have higher total energy, cholesterol, and fat intake and lower vegetable and fruit intake [43
]. Moreover, children of unemployed parents or lesser income families consumed unhealthier DF, derived from energy-dense, low nutritious foods. The cost of healthy food, reduced food choices, and lack of education in low SES families might lead to lower vegetable- and fruit-derived fiber intake and, consequently, a higher prevalence of children at risk to become overweight or obese, and to develop chronic diseases [20
]. Children with both employed parents, however, had less DF intake than those with one-employed parent in our study, which might be influenced by parents having less free time.
We observed that dietary sources from vegetables and fruit contributing to DF intake in our study were much less compared to other food sources based on the quartiles of total fiber intake. Although vegetables and fruit were ranked second and fifth in DF contribution, children had extremely lower DF intake from raw vegetables (1.8%) compared to cooked ones (10.0%). In addition, in our findings, children of higher educated mothers and secondary educated fathers and those with one or both parents being employed had more DF intake from vegetables and fruit, which indicates that lower secondary educated and unemployed families need to be targeted during health promotion campaigns. Our results also suggest that the level of maternal education is more indicative for dietary habits of their preschool aged children than the level of paternal education.
4.3. Strengths and Limitations
The present study was the first food consumption survey among preschoolers comparing associations between total and food group-specific DF intakes and SES in Belgium while covering the whole Flemish region. Therefore, the results of this large cross-sectional study represent the Flemish preschool children’s dietary habits with a good representation compared to the more local and small-scale surveys that were executed before.
Like all studies, some limitations should be taken into consideration. First, this study suffered from some selection bias, with the lower SES group being underrepresented [24
], which might have influenced the true DF intake and the linear associations.
Furthermore some limitations regarding the dietary assessment method are noteworthy. No dietary assessment method is perfect and every method is prone to some degree of misreporting. The method of 3d EDR reflects the individual children’s short-term rather than usual intake. However, we corrected for within-person variability by using the MSM method to obtain a more precise individual usual daily DF intake. The percentage of under-reporters, excluded in this study, in the final sample for analysis was very low (2%). In addition, a relative validation study was conducted in which the results derived from a food frequency questionnaire were compared with those derived from our 3d EDR for calcium intake, food intake and for a diet quality index [41
Moreover, the decisions regarding the food grouping were based on the Flemish FBDG and on the judgment of the investigators, which might have implications for the findings. The food composition of fortified foods, highly consumed by Flemish preschoolers, was rather hard to define and, in some cases, information from the industry or from packing materials had to be used. Furthermore, the definition of DF in Belgium is considered as carbohydrates with three to ten monomeric units, which might result in differences with international recommendations [51
]. Also, no real information is available on the low molecular weight DF fraction and limitations of AOAC methods used [52
]. Our dataset was not adjusted for possible alterations in fiber content or quality due to food processing, which may have attenuated the accuracy of our total DF estimates.