Every molecule or nutrient we ingest has potential impact on our brain health and cognitive function yet we know surprisingly little about these relationships.
Each piece of food, or sip of drink you ingest during the day, whether as part of your regular meals or an occasional snack break, contains a specific set of nutrients. This includes macro-nutrients such as carbohydrates, proteins, fats which provides the body and brain with the major building blocks that it needs to survive. Beyond this there are also scores of micronutrients – the tiny minerals, vitamins and other molecules that are essential for the healthy functioning of the human brain – playing a role in everything from enzymatic activity to neuroplasticity.
It therefore stands to reason that food choices – both in terms of what you eat and when you choose to eat – have an impact on the functioning of the brain. What are they? And critically, what impact do these choices have on children who are still very much within a critical period of neural development? Surprisingly, we know fairly little.
Linking Diet to Cognition
Vitamins such as A and C have been shown to improve performance on spatial working memory tasks in rats and also on performance on cognitive tests in children, particularly those with impoverished diets. That said, there are numerous such studies and study results vary a fair bit based on the specific micronutrient tested, the type of cognitive task and the age of the children in the study.
One recent study from Jin Young Kim and Seung Wan Kang in South Korea took a different approach and rather than providing a particular micronutrient supplement, examined how different habitual dietary choices could influence a child’s cognitive functioning.
They asked 317 children (aged 6-18) to complete a questionnaire on their consumption (the frequency and amount) of 76 common foodstuffs which contain different levels of micro and macro-nutrients, to compile an approximation of their individual daily nutrient intake. They then asked the participants to undertake a neurocognitive battery of tests – the CNSVS – and a visual Go/NoGo task. By assessing performance on these tests and comparing it against their nutrient intake and food choices they attempted to link the two together through correlational analysis.
When analyzing the data by estimating micronutrient intake the authors found significant positive correlations between vitamin B1, vitamin B6, vitamin C and potassium and performance on specific tasks within the neurocognitive battery (e.g. digit span). In addition they found that eating foods containing protein, vitamin D, vitamins B1, 2, 6, niacin and zinc was negatively correlated with the number of inattentional performance errors on the Go/NoGo task.
From noodles to nuts
When looking at broader food groups however, the results were statistically more robust. Consumption of instant noodles and plain white rice was very significantly associated with performance across several of the tasks within the neurocognitive battery, including verbal memory and mental reasoning. Drinking Coca Cola and eating fast food also was also negatively correlated with some aspects of cognitive performance. In contrast eating nuts, mushrooms, vegetables, meat and poultry was positively correlated with key aspects of task performance.
The results seem to add support to the well-established view that eating unhealthy fast foods, foods such as instant noodles, or not eating a balanced diet can all be detrimental to the brain’s ability to perform optimally. That said, this study by no means establishes a causality. Various other factors of context and upbringing could play a confounding role. There is also the confound of the timing of when you eat, which matters for how you perform on tasks.
See related post Human Brains and the Control Issue.
When you eat, how you perform.
A study by R.T. Pivik and colleagues from Arkansas Children’s Nutrition Center focused on how eating or skipping breakfast influenced performance on a mental arithmetic task in children aged between 8-11 years (n=81). They divided the children into two groups – a group who ate breakfast and a group who skipped breakfast and compared performance between test sessions before and after eating (or not eating) breakfast. As may be expected, children who ate breakfast produced a greater number of correct responses, whilst those who skipped breakfast were not only less accurate in their answers, but also gave their answers more quickly.
Another study by Sampasa-Kanyinga and Hamilton in Canada showed a relationship between how regularly students ate breakfast and academic performance.
Linking nutrition and brain dynamics
What do all these meals and nutrients do to our brain dynamics? There are surprisingly few studies to speak of. Pivik et al is one of the few that recorded EEG over parietal and frontal regions along with task performance. Specifically, they found relatively greater alpha and theta activity across parietal and frontal regions in those who skipped breakfast, compared to those who ate breakfast. This is perhaps contrary to expectation since higher alpha has typically been associated with higher attention. On the other hand it potentially reflects an increased effort of attentional systems required in fasters. Or perhaps comes back to potential confounds both in other aspects of participants and also in analytical approaches to signal processing.
See related post The Blue Frog in the EEG.
There is no doubting that the food we choose to eat is critical for our cognitive health. However, teasing out the precise relationship between dietary choices and cognitive function requires controlling for a host of other factors that are likely to play a confounding, looking widely across a wide range of micronutrients as well as understanding nutrient interactions. Given the global variance in food availability and dietary preferences, this area lends itself to large scale interrogation. Findings in the future will not only help to ensure that individuals can tailor their global dietary choices and habits to optimize their thinking, but also provide evidence to support policies which encourage healthy brain development.