Nutritional influences in the development of the brain

Critical and sensitive periods        

In terms of cognitive development, we can distinguish several sensitive and critical developmental stages during which a special type of environmental stimulus facilitates the process. A critical stage is a relatively short period that starts and ends at quite precise moments. During this period, the body is vulnerable to influences like those caused by certain aspects of nutrition. Such examples are the negative effects triggered by an iron or iodine deficiency in the initial stages of brain development. During a critical stage, these is an increased sensitivity to environmental stimuli; however, if there is no stimulus, then it is going to be difficult, if not impossible, that an aspect of the brain performance be expressed later in life. Therefore, if malnutrition hinders metabolical processes at a certain age, there is the risk of a long-term side effect on cognition.

On the other hand, a sensitive period is seen as a window of opportunities in which the brain is sensitive to a certain type of stimuli. For example, language is much more easily acquired during the first ten years of life. Although particular functional aspects are gained without difficulty during a sensitive period, an ability can still be achieved at a later age, albeit not as easily and not at the same level of competence and good command.

The alleged differences between sensitive and critical stages of development are usually subtle, and the stated appreciations vary from one worker to another, and according to discipline. Some of them noticed that children fall short at a certain developmental stage if they lack the stimulation characteristic to a critical window of opportunities. At the opposite end, others believe that there are only sensitive periods, and that a lack of stimulation does not produce difficulties which could not be overcome later, even with a greater effort.

At least, as far as nutrition is concerned, there is good evidence regarding the critical stages of development. As the brain develops rapidly during pregnancy, an inadequate diet can limit the development of important aspects related to brain structure. The argument is that, since it is the mother’s diet that provides the nutrient blocks from which the baby’s brain is made, if during a period of fast brain growth an aspect of nutrition is inappropriate, permanent brain damage can occur.