Timing and composition of the meals

The energy required by the functioning of the brain is also supplied through the food we eat

There are reasons to believe that children, more than adults, can be more prone to building glucose provisions. Proportional with corporal weight, children’s brains as bigger that those of adults, thus reflecting the rapid brain growth during the perinatal period. More than that, a given amount of brain tissue of a child uses more glucose than the same amount of brain tissue of an adult. The use of glucose per gram of brain tissue increases until the age of 4, when the brain requires almost double the energy compared to an adult brain. A fast rate of glucose consumption continues until the age of 9 or 10, after which it starts to decline, reaching a normal adult rate by the end of adolescence. Since the brain of a child is relatively bigger and more active than that of an adult, it is highly possible that children are more dependent on meals at regular intervals. The idea that the rate at which glucose is released into the bloodstream may influence the functioning of children is supported by studies that examined the effects of a drink containing glucose. During afternoon hours, children between 9 and 11 years of age remembered things better and spent more time on a task in comparison with the children who received a placebo. Similarly, by the end of the school day, 7-year-old children displayed an increased ability of paying attention and showed a lower risk of feeling frustrated after having a glucose drink.

There has been a particular interest on the effect of breakfast on the behavior of children. After revising this subject, a group of analysts concluded that, as data shows, skipping breakfast interferes with learning and cognition, an effect that is more extensive in children that are already at risk of malnutrition than in the well-fed ones. For example, eating breakfast instead of fasting improved cognitive performance in children of 9 to 11 years of age as soon as one hour after eating. The ability to maintain focus was better one hour after breakfast in children aged 9 to 12, although memory was not affected. However, 12-year-old children showed a better memory 30 minutes (but no later than that) after they had a bowl of cereals for breakfast, compared with those who fasted. The general impression generated by these studies was that the benefits were on short term, although more recently it was proven that it is the composition of the food that matters, when trying to establish a meal that would offer longer-term improvement.

In young adults, when different breakfast meals were compared with respect to the differences in the type of carbohydrates provided, if glucose was released more slowly, the memory was better until the end of the day. In the same way, when different breakfasts were compared with regard to their macronutrient components, a better memory was associated with an increased tolerance to glucose and the consumption of foods that released glucose more slowly in the bloodstream.

A way of interpreting these findings is that the cognitive functioning of a child benefits from a gradual release of energy. A study that linked the size of children’s breakfast and whether a snack was consumed afterwards to cognitive functioning had results that were consistent with this approach. Eating a small breakfast, containing approximately 61 Kcal, was associated with less time spent on school work. However, in these 9-year-olds, the negative effects of a small breakfast were overcome by the consumption of a snack later in the morning. The snack had no effect on children who had eaten a richer breakfast. Similarly, in Indian children aged 7 to 9, who consumed meals that differed by the morning hour at which they were eaten,  it was observed that a midmorning snack improved memory in those with a low socio-economic status but not in those with a higher socio-economic status.

In conclusion, there is a serious amount of evidence showing that various nutriments – including iodine, iron, zinc, choline, vitamin B12, folate and vitamin D – play important roles in the development of the brain. It has been suggested that an examination of these substances would help identify other nutrients that might be important in a similar manner – that is, those that are essential in cell division – whose level of intake varies greatly between individuals and whose biosynthetic capacity is absent or very limited.