[1] The human brain requires nutrients obtained from the diet to develop and sustain its physical structure and cognitive functions.
Each macronutrient can impact cognition through multiple mechanisms, including glucose and insulin metabolism, neurotransmitter actions, oxidative stress and inflammation, and the gut-brain axis.
[4] Simple carbohydrates impair cognition through glucose and insulin metabolism dysfunction, as well as causing inflammation and oxidative stress within the brain.
[4][5] The essential amino acids tyrosine and tryptophan are precursors for the neurotransmitters dopamine, serotonin, and norepinephrine, and these chemicals modulate neural activity and influence cognitive functioning.
[4][13] Dietary protein can improve cognition by increasing reaction time and inhibition control during mentally demanding and physically stressful situations, as tyrosine and tryptophan will replenish exhausted neurotransmitter levels.
[4] However, the adverse cognitive effects of cholesterol consumption appear to be reduced when combined with physical activity, which influences energy homeostasis and synaptic plasticity.
[4] Saturated fatty acids are typically solid at room temperature with common sources including butter, cheese, and meat.
Trans fatty acids occur naturally in some meat and dairy products, however the majority are artificially created by hydrogenating vegetable oils and are present in many processed foods.
[2] This vitamin is important for the facilitation of glucose use, thus ensuring the production of energy for the brain,[2] and normal functioning of the nervous system, muscles and heart.
[20] Vitamin B3, also known as niacin, includes both nicotinamide as well as nicotinic acid, both of which function in many biological oxidization and reduction reactions within the body.
Niacin is involved in the synthesis of fatty acids and cholesterol, known mediators of brain biochemistry, and in effect, of cognitive function.
[21] Folate and vitamin B12 play a vital role in the synthesis of S-adenosylmethionine, which is of key importance in the maintenance and repair of all cells, including neurons.
[22] In addition, folate has been linked to the maintenance of adequate brain levels of cofactors necessary for chemicals reactions that lead to the synthesis of serotonin and catecholamine neurotransmitters.
[26] Because neurulation may be completed before pregnancy is recognized, it is recommended that women capable of becoming pregnant take about 400 μg of folic acid from fortified foods, supplements, or a combination of the two in order to reduce the risk of neural tube defects.
It is recommended for the elderly to consume folate through food, fortified or not, and supplements in order to reduce risk of developing the disease.
People who suffer from irreversible causes of deficiency, such as pernicious anemia or old age, will need lifelong treatment with pharmacological doses of B12.
Abnormal myelination of white matter due to iron deficiency during development may be related to the onset of psychological disorders in adolescents.
[34] Decreased iron concentration results in a reduction of neurotransmitter levels, in turn leading to poor myelination and delayed neuromaturation.