A friend recently met her daughter’s teacher to discuss concerns about her progress. She came away not with extra homework or advice, but with a packet of flax seeds. She claims she was asked to sprinkle them liberally on her daughter’s cornflakes. But can what we eat really have such an influence on our learning?

Faced with an essay or revision crisis, a college student’s first dietary recourse may be caffeine. Caffeine is defined as a stimulant, but its cognitive effects on those with a “habit” are not well publicised.

When researchers asked adults with and without a caffeine habit to carry out cognitive tests at breakfast time, they found regular caffeine users did worse than non-caffeine users.

The abilities of regular users only returned to baseline after their caffeine fix. This is also true for younger caffeine-heads. As the only psychoactive drug legally available to children, “use” is widespread. The average vending machine now delivers a 500ml bottle of cola with the same amount of caffeine as a cup of coffee.

Research has shown that caffeine withdrawal - with symptoms of headaches and fatigue - is common among children. Thinking ability is also affected. Children aged nine to 10 who habitually consume the equivalent of no more than two 300ml cans a day of cola demonstrate decreased alertness.

As with adults, the cola “caffeine fix” provides only a momentary return to the state of alertness offered by a caffeine-free lifestyle. Many of us are also suspicious of the strangely coloured drinks beloved by children in the belief that their sugar content contributes to hyperactivity. Rather than sugar, however, recent research has implicated a range of colourful E-numbers. Wisely, UK food manufacturers appear set to phase these out by the end of the year.

So that’s the bad stuff, but what’s good for brains? Fish has had good press for centuries, as an important symbol for Christians, Hindus and Muslims. Some historic links with health are more direct: in Buddhism, it represents vision and in Judaism the Talmud gives “advice to pregnant women ... one who eats fish will have graceful children”.

That’s almost spookily accurate, because maternal fish consumption appears to improve a range of childhood behaviours contributing to “graceful” behaviour, including verbal IQ, fine motor control and social behaviour.

Most recently, scientists braved the Canadian Arctic to study Inuit mothers’ consumption of fish and their babies’ abilities at six and 11 months. They noticed many Inuit were still enjoying a traditional fish-rich lifestyle, while others had developed more Western tastes.

This allowed scientists to confirm the positive effects of maternal fish eating on the cognitive, motor and - echoing Buddhist perspectives - visual abilities of their child. Fish (like flax seeds) is an important natural source of omega-3 hyperunsaturated fatty acid, which is often called an essential fatty acid because our bodies cannot create it and so we must consume it.

Interestingly, however, levels of this acid in the breast milk of Inuit mothers was not so influential, suggesting that the spurt in neural connection-making during the last months of pregnancy is what benefits most from the mother’s fish-eating habits.

We know that omega-3 is vital for brain function throughout life and, since we gave up hunter-gathering, our intake has been plummeting. Research involving John Stein, the neuroscientist brother of chef Rick, added to growing evidence of links between omega-3 levels and dyslexia (and other developmental disorders).

Most temptingly, his research showed that reading ability was related to omega-3 levels in dyslexic and non-dyslexic groups.

Such findings appear to support the flourishing of “clever” omega-3 products on supermarket shelves. But, despite clever marketing, we don’t have firm evidence that supplements are of benefit to the general population.

In Taiwan, research showed supplement taking was linked to school performance, but it did not seem to matter which supplement. Supplements came with wealthier and better educated home environments, and these appeared to be the key factors for school success, rather than the supplement itself.

Whatever the controversy about supplements, there is one thing pupils can consume that is almost guaranteed to benefit their learning: breakfast. It’s an important part of good, regular, dietary habits, and such habits have been identified as the number one nutritional issue affecting educational performance.

It’s not new or exciting, and some may find it unimaginable that parents can ever send their child to school without breakfast. But, as the father of a teenager who hates mornings, I know how challenging it can be to get the learner to the breakfast table.

Furthermore, I can report that sprinkling flax seeds on his favourite cereal hasn’t, as yet, made him approach the breakfast table any faster.

Paul Howard-Jones is a senior lecturer in education and co-ordinator of the Centre for Psychology and Learning in Context (CPLiC) at the Graduate School of Education, University of Bristol.

REFERENCES

Bellisle, F. (2004) Effects of Diet on Behaviour and Cognition in Children. British Journal of Nutrition, 92(S2), S227-S232

Chen, S. Y., Lin, J. R., Kao, M. D., Hang, C. M., Cheng, L., Pan, W. H. (2007) Dietary Supplement Usage among Elementary School Children in Taiwan: Their school performance and emotional status. Asia Pacific Journal of Clinical Nutrition, 16(S2), 554-563

Cyhlarova, E., Bell, J. G., Dick, J. R., MacKinlay, E. E., Stein, J. F., Richardson, A. J. (2007) Membrane Fatty Acids, Reading and Spelling in Dyslexic and Non-dyslexic Adults. European Neuropsychopharmacology, 17(2), 116-121

Heatherley, S. V., Hancock, K. M. F., Rogers, P. J. (2006) Psychostimulant and other Effects of Caffeine in 9 to 11-year-old Children. Journal of Child Psychology and Psychiatry, 47(2), 135-142

Jacobson, J. L., Jacobson, S. W., et al (2008) Beneficial Effects of a Polyunsaturated Fatty Acid on Infant Development: Evidence from the Inuit of Arctic Quebec. The Journal of Pediatrics, 152(3), 356-364.