Assuming a diet is not deficient; this is a brief overview of some of the dietary needs for optimal brain function.
Maintaining glucose levels is necessary to maintain healthy brain function.
There is substantial research on the positive effects of omega 3
fatty acids on brain function.
Vitamin and mineral deficiencies can cause disruption to brain function (note so can excesses).
This article gives some good detail about how to maintain healthy glucose levels; with discussion of glycaemic index and maintaining a steady release of glucose from the breakdown of complex carbohydrates.
Nourish - Carbohydrates Fuel Your Brain
Glucose, Learning and Memory - Study
Psychology professor Paul E. Gold has researched the stability of glucose levels in the brain. Working with Ewan C. McNay , they found that as rats went through a maze, concentrations of glucose declined in the animals' hippocampus , a key brain area involved in learning and memory – even more dramatically so in older brains.
Except under conditions of starvation, it was thought that the brain always had an ample supply of glucose. "While this is the case in terms of consciousness, the new findings suggest that glucose is not always present in ample amounts to optimally support learning and memory functions," said Gold, who is director of the Medical Scholars Program in the University of Illinois College of Medicine.
"The brain runs on glucose. Young rats can do a pretty good job of supplying all the glucose that a particular area of the brain needs until the task becomes difficult," explained McNay, a postdoctoral researcher in psychology at Yale University. "For an old rat given the same task, the brain glucose supply vanishes out the window. This correlates with a big deficit in performance. A lack of fuel affects the ability to think and remember."
Brain Energy Metabolism
An Integrated Cellular Perspective
Pierre J. Magistretti, Luc Pellerin, and Jean-Luc Martin
Glucose is the obligatory energy substrate for brain and it is almost entirely oxidized to CO2 and H2O.
Role of glucose in regulating the brain and cognition.
P E Gold
Extensive evidence indicates that relatively modest increases in circulating glucose concentrations enhance learning and memory processes in rodents and humans.\
Omega 3 fatty acids:
Lipids (fats)- some fats are essential for proper brain function. Two lipids especially critical to the brain are the n-6 and n-3 fatty acids. Low levels of n-3 cause visual problems by badly affecting the retina. Studies in rats have shown that diets without n-3 fatty acids cause learning and motor disabilities and may damage systems that use the neurotransmitters dopamine and serotonin in the frontal cortex. The n-6 fatty acids affect neurotransmitter release and contribute to the ability of neurons to use glucose for energy.
Brain foods: the effects of nutrients on brain function
Fernando Gómez-Pinilla doi: 10.1038/nrn2421
... a diet that is rich in omega-3 fatty acids is garnering appreciation for supporting cognitive processes in humans and upregulating genes that are important for maintaining synaptic function and plasticity in rodents. In turn, diets that are high in saturated fat are becoming notorious for reducing molecular substrates that support cognitive processing and increasing the risk of neurological dysfunction in both humans and animals.
B vitamins and the aging brain.
Selhub J, Troen A, Rosenberg IH. doi: 10.1111/j.1753-4887.2010.00346.x.
Deficiencies of the vitamins folate, B(12) , and B(6) are associated with neurological and psychological dysfunction and with congenital defects. In the elderly, cognitive impairment and incident dementia may be related to the high prevalence of inadequate B vitamin status and to elevations of plasma homocysteine
The Vitamin You Need for a Sharp Brain as You Age
Accordingto the latest research, people with high levels of markers for vitamin B12 deficiency were more likely to score lower on cognitive tests, as well as have a smaller total brain volume, which suggests a lack of the vitamin may lead to brain shrinkage
Vitamin B12, cognition, and brain MRI measures: a cross-sectional examination.
Tangney CC, et al doi: 10.1212/WNL.0b013e3182315a33.
Concentrations of all vitamin B12-related markers, but not serum vitamin B12 itself, were associated with global cognitive function and with total brain volume.
Vitamin D, effects on brain development, adult brain function and the links between low levels of vitamin D and neuropsychiatric disease.
Eyles DW, Burne TH, McGrath JJ. doi: 10.1016/j.yfrne.2012.07.001
Increasingly vitamin D deficiency is being associated with a number of psychiatric conditions. In particular for disorders with a developmental basis, such as autistic spectrum disorder and schizophrenia the neurobiological plausibility of this association is strengthened by the preclinical data indicating vitamin D deficiency in early life affects neuronal differentiation, axonal connectivity, dopamine ontogeny and brain structure and function. More recently epidemiological associations have been made between low vitamin D and psychiatric disorders not typically associated with abnormalities in brain development such as depression and Alzheimer's disease
The following link gives a good overview of vitamin deficiencies and toxicities.
Fat-Soluble Vitamins: A, D, E, and K
by L. Bellows and R. Moore
Fat-soluble vitamins: A, D, E, and K — are stored in the body for long periods of time, and pose a greater risk for toxicity than water-soluble vitamins. Fat-soluble vitamins are only needed in small amounts.
Note: that, within all scientific research,there can be research that is "conclusive", but it is also important to be mindful, that not all findings are conclusive.
Vitamin D and cognitive performance in adults: a systematic review.
Annweiler C, et al doi: 10.1111/j.1468-1331.2009.02755.x.
. Three studies showed four significant positive associations between serum 25OHD concentrations and global cognitive functions, whereas three other studies exploring specific aspects of cognition showed 11 non-significant associations. This systematic review shows that the association between serum 25OHD concentrations and cognitive performance is not yet clearly established. The inconclusive results of the reviewed studies could be due to methodology, types of the cognitive tasks used and/or the cellular mechanisms of vitamin D.