Our data provide additional support for the observation that the fat intake of children in developing countries decreases as breast milk is displaced from the diet (7
). Overall, all children 24–48 months old were consuming a low fat, high carbohydrate diet. Both younger and older breastfeeding children had significantly higher fat intake as a percent of total energy when compared to their non-breastfeeding counterparts in the same age category. Breastfeeding children in the 24–35 month age group had the highest mean fat intake as a percent of total energy at 19.5%. Almost all children in the study, however, had fat intakes below the recommended usual intake of 30% of total energy. In general, children from households with better housing quality and more educated mothers had higher fat intake. Fat intakes were also higher in older children living in Pirgacha versus Trishal. However, the average absolute differences were small, and the diets of all children were low in fat.
Of particular concern is the large percentage of children who were estimated to be consuming a very low fat diet (less than 10% of total energy from fat). It was estimated that 30–40% of all non-breastfeeding children and 16% of older breastfeeding children had fat consumption below this level. Prentice and Paul considered this to be a very low level of fat intake in children that was “not widely prevalent,” even in the developing world (7
Most children had EFA intakes that were less than the lower levels recommended by FAO/WHO and the U.S. IOM, but greater than the absolute minimum levels estimated to prevent EFA deficiency (8
). Although intake of EFA was low, most children had LA:ALA intake ratios that fell within the recommended range of 5:1 to 10:1 (9
). Breastfeeding children in both age groups had lower intake of ALA compared to non-breastfeeding children; this is most likely because of the very low ALA levels found in the breast milk samples from the women in this study.
A few other studies have examined fat intake in preschool-age children, and in general, children in this study had lower levels of total fat and EFA intake and similar levels of long-chain fatty acid intake. All groups of children in this study had estimated mean intakes of fat as a percentage of total energy that were much lower than the 34.6% reported by Innis et al. for 25–36 month old Canadian children (30
). One to five year old rural Chinese children were estimated to consume 21–24% of total energy from fat, which is similar to that observed for breastfeeding children in our study, but still much higher than that observed for non-breastfeeding children (31
). Absolute LA and ALA intake for Bangladeshi children were similar to those observed for the Chinese children (~2 g LA/d and ~0.3 g ALA/d), but less than half of the ranges of intake observed for LA (~6–9 g/d) and ALA (~0.7–2 g/d) in the diets of preschool-age children from Australia, Canada, and Belgium (30
). Interestingly, the ARA and DHA intake of the Bangladeshi children was within the general range observed for children from the studies in Canada, China, Australia and Belgium (0.02–0.26 g ARA/d and 0.02–0.1 g DHA/d) (30
). All of these studies used different dietary intake methodology and food composition databases, so there may be some limitations to these comparisons.
Important sources of fat for the children in our study included vegetable oil, rice, and locally produced and pre-packaged snacks and biscuits. ASF provided about one-fourth of total fat for young children. The probability of consuming different types of oil and ASF varied by district of residence, indicating that local preferences and availability must be taken into account when planning food-based interventions. In both sites, breast milk was a significant contributor to fat intake in breastfeeding children. In particular, it was an important source of DHA. Younger breastfeeding children consumed significantly more DHA than their non-breastfeeding peers. In older children, however, breast milk consumption was not associated with higher DHA intake, most likely because amount of breast milk consumed is lower in this age group.
Overall, the prevalence of stunting for children in this study was very high and in agreement with the 2007 Bangladesh Demographic and Health Survey, which found that 53–54% of 24–47 month old children were stunted (16
). It is important to note, however, that this is a cross-sectional study, and we cannot establish a causal relationship between low fat intake and growth in these children. Although breastfeeding children generally had higher fat intakes, children in the older age group had significantly lower height-for-age z-scores compared to their non-breastfeeding counterparts after adjusting for several potential confounders. There was a trend for lower energy intake in breastfeeding versus non-breastfeeding children, but the difference was not significant in either age group after adjusting for other factors. It is possible that there was a nutrient other than energy or fat that was growth-limiting in breastfeeding children (7
). The negative association between breastfeeding and height-for-age z-score may also be due to reverse causality if mothers are less likely to stop breastfeeding a child in poor health, as has been previously described by Marquis et al. in Peru (34
One strength of our study was that we collected quantitative data on daytime consumption via direct observation and weighing of foods and test weighing of breastfeeding children. Another strength is that we used statistical methods developed by the National Cancer Institute to account for episodic consumption of foods and nutrients and to remove within-person variation from our estimated usual intake distributions. It is possible, however, that we may have under- or over-estimated fat intakes in these children. Children did have some food intake that was estimated via recall, although their main meals were generally consumed during the 12-hr in-home observation period. The mean contribution of energy from the recall period for the children was low (65 kcal/d). To improve maternal recall of child intake, field workers used locally developed standardized plates, cups, and spoons to assist with portion size estimation and a multiple pass method to minimize omissions.
It is possible that mothers may not have witnessed some of their children’s food intake, since children often moved between households and relatives. However, children were more likely to be in the home with the mother during the early morning and evening periods that the recall covered. Another potentially significant source of error is the conversion of food intakes to nutrient intake using food composition data. The nutrient composition of foods can vary significantly by geography and season, and budgetary constraints prevented us from directly analyzing foods from the study area to determine their fatty acid composition. To partially address this, we have presented quantitative data on food intake to support the nutrient intake data.
Some potential problems with estimating fat intake were specific to breastfeeding children. Breast milk samples were not available from the mothers of all breastfeeding children in the study, so values for total fat and individual fatty acids in breast milk were based on the average composition of the samples that were analyzed from a subset of the mothers (n=98). Ideally, we would have been able to analyze samples from all of the mothers, as the breast milk fatty acid composition can vary considerably based on maternal diet. Our estimated median total fat content of the milk (3.5 g/dl) was within usually reported concentrations internationally, but may be inappropriately high given that the breastfeeding mothers in the current study were generally lean (42% had a BMI <18.5) (22
). It is possible that this relatively high fat content is a result of using a spot sample to estimate total breast milk fat content. It has been shown previously that the total fat content of fore- and hind-milk differs (35
), so spot samples taken later in the feed may have contained unrepresentatively high fat concentrations. In contrast with the present results, the mean fat content of breast milk at eight months postpartum was just 2.8 g/dl among similarly nourished Bangladeshi mothers included in an earlier study that used full milk expression (36
). If our value for the total fat content of milk was too high, we may have overestimated the fat intake of breastfeeding children. Therefore, we also estimated the distribution of fat consumption as a percent of total energy using a lower value for breast milk fat content [2.8 g/dl], and found that using a lower mean fat content for the breast milk had only a small effect, increasing the percentage of breastfeeding children whose fat consumption was below 10% of total energy from 4 to 6% in the younger age group and from 16 to 20% in the older age group. It should be noted that the fatty acid composition of breast milk can be reliably determined from a spot sample (35
It is also possible that we may have under- or over-estimated the intake of breastfeeding children because we extrapolated mean daytime intakes (amount per feed) of breast milk to nighttime feeds. Due to logistical and safety issues, we could not do any test weighing at night, so we do not know if our assumption for extrapolation of daytime to nighttime amount per feed is correct. It is possible that preschool age children consume more milk at night than during the day because food consumption displaces breast milk intake during the day.
Both breastfeeding and non-breastfeeding 24–48 month old Bangladeshi children have fat intakes below levels recommended by FAO/WHO and the U.S. IOM. It is possible that preschool-aged Bangladeshi children could benefit from increased fat intake. This would need to be achieved without reducing the micronutrient density of the diet (37
). Thus, studies of lipid-based multiple micronutrient supplements should be considered in this population. It is important that these studies be tied to biochemical and functional outcomes to better inform fat intake requirements for children in this age group. Finally, it is likely that Bangladeshi children would also benefit from an enhanced EFA profile in breast milk if the fatty acid profile of the maternal diet were improved.