Milk Cereal Drinks, Infant Growth and Later Risk of Obesity

At least during the last 600 years, ‘pap’ or ‘gruel’ (a mixture of bread, cereal grains and water or milk) has at times been used to supplement or replace breast milk for weaning infants [1]. Commercial baby foods based on a combination of milk and cereal have been available since the mid-1800s and have been commonly used since the mid-1900s. These can be in the form of porridge or a ‘milk cereal drink’ (MCD).

The use of baby porridges and gruel varies over time and between different cultural settings. Commercial MCDs (‘välling’) are uniquely popular in Sweden, consumed by a vast majority of infants (75%–85%) at 12 months of age [2, 3]. Commercial MCDs are iron-fortified, fed by bottle and largely replace follow-on formulas (infant formulas designed for use from 6 months and onwards), which are more commonly used in other countries.

However, there is some evidence that MCD consumption is associated with development of overweight and obesity [2]. The mechanism has been suggested to be rapid weight gain during infancy, which has been associated with later obesity [4]. It is therefore highly relevant to investigate this further.

In a recent article in Acta Paediatrica [3], Lindholm et al. set out to study this possible mechanism by investigating the effects of milk cereal drink consumption at 6–12 months of age among 656 children who were followed from infancy to school age. For assessment of rapid weight gain, the authors used anthropometric data collected at routine check-ups at child healthcare centres. Rapid weight gain was a binary variable defined as a change of > 0.67 in weight SD score between 6 and 12 months, according to Ong and Loos [4]. Weight gain was also assessed as a continuous variable.

Data on MCD consumption and breastfeeding during infancy were collected retrospectively when the children were 2–9 years old. Outcome data on BMI and waist-to-height ratio were collected prospectively at 8–15 years of age. MCD consumption at 6–12 months of age was reported by 62% of parents and was associated with increased weight gain (as a continuous variable) during this time interval (r = 0.12, p < 0.01) even though this association was no longer significant when using the binary outcome of rapid weight gain. Rapid early weight gain was, in turn, strongly associated with overweight (OR 2.5, 95% CI 1.2–5.4) and high waist-to-height ratio (OR 4.0, 95% CI 1.2–13.9) at school age, whereas MCD consumption, paradoxically, was not.

The Lindholm study contributes important information regarding the positive association between MCD consumption and weight gain at 6–12 months of age. However, the authors were not able to confirm the hypothesis that MCD increased rapid weight gain when analysed as a binary variable. As expected, breastfeeding was shown to be a significant protective factor against rapid weight gain, whereas data on formula feeding and other food intake were not included in the study.

Furthermore, the study supported previous observations that rapid weight gain at 6–12 months of age is a strong risk factor for later overweight, which is important information and opens up possibilities for interventions.

The authors could not show any association between MCD consumption and later overweight; this despite that the same research group previously found in a study of 1870 children that daily consumption of MCDs at 12 months of age was associated with a twofold higher risk of being overweight at 5 years of age (OR 1.94, 95% CI 1.08–3.50) [2]. The results from that previous study may be more reliable since the sample size was higher. Furthermore, the previous study had higher quality dietary data, which in that case were prospectively collected and the number of bottles consumed per day was recorded.

Thus, the recent Lindholm study confirms the association between MCD consumption and early weight gain, which is known to be associated with later risk of overweight. The authors speculate that the mechanism may be bottle feeding since it has been suggested that this feeding mode is associated with a more non-responsive feeding style and thus higher intakes. However, we have shown in a randomised controlled trial that infants are very capable of self-regulating energy intake when bottle-fed [5]. A more plausible explanation is that MCDs have a considerably higher protein concentration than breast milk. MCDs typically have a protein content of about 2 g/100 mL or 2.7 g/100 kcal, whereas mature breast milk has a protein content of about 1 g/100 mL or 1.6 g/100 kcal. Higher protein intakes during infancy have been shown in a large European randomised controlled trial to result in increased BMI and obesity risk at school age [6].

Historically, cereal have traditionally often been added to milk bottles [7] and this practice is still common in some socio-economic and cultural settings. A more recent US study showed that low-income mothers commonly add cereal into the bottle, most often with the intention of increasing satiety and improve sleep [8]. Internationally, commercial MCDs are often marketed as so-called ‘good-night milks’, with the claim that they help babies sleep better during the night. However, the effects of added cereal on satiety and sleep have not been studied in any detail so there is no evidence-base for any effect of MCD on sleep quality in infants.

In conclusion, the recent Lindholm study, in combination with the previous results from the same research group, suggests that MCDs are associated with higher weight gain during infancy and possibly increased risk of overweight at school age, while breastfeeding seems to be protective. This supports the current recommendation that infants should breastfeed exclusively up to about 6 months and partially at 6–12 months of age.

Follow-on formulas are an alternative to MCDs if the parents choose to bottle-feed the infant at 6–12 months of age. Another option is porridge. Like MCDs, follow-on formulas and commercial baby porridges are normally fortified with iron, which is important during late infancy when the risk of iron deficiency otherwise is high. Unfortunately, there is a severe lack of studies comparing these different complementary foods against each other, so high-quality studies on this topic should be a high priority. One interesting future study would be to investigate growth trajectories in children fed MCDs with standard vs. lower protein content.

The author declares no conflicts of interest.