Exploring the impact of diet on productivity and energy levels

The brain is constantly working and it never stops functioning, even during sleeping hours 1. This means it requires a continuous supply of fuel, i.e. energy coming from food. Just like cars, the brain works best when it only gets ‘premium fuel’ and hence, what we eat directly impacts the brain’s structure and function.

Optimal cognitive function is a crucial aspect of brain health and wellbeing 2. The brain consumes a tremendous amount of energy relative to the rest of the body, and dietary factors are found to affect multiple brain processes 3. Vitamins and minerals, in particular, have multiple functions within the central nervous system that may result in maintaining brain health and optimal cognitive functioning 4. A growing body of evidence suggests that these so-called ‘neuro-nutrients’ along with eating behaviours in general, could impact the pathogenesis of some neurological disorders, and the cognitive and emotional state of people 4.

Regarding specific food groups and their impact on brain health, the evidence base is scarce; few studies have been conducted on specific food groups either in the general population or within specific age groups 2. Evidence relevant to the effects of legumes, fish, and meat on cognitive function are mainly restricted to specific subcomponents (i.e. nutrients-ingredients within that food group) 2.

Plenty dietary factors have been identified as having direct and indirect effects on cognitive abilities 3:

Dietary lipids (fats), which were initially thought to impact the brain through their cardiovascular effects, are now recognized for having a direct impact on the brain 3

The human body can produce most of the types of fats it requires from other fats or carbohydrates 5. However, the body is incapable of synthesizing omega-3 polyunsaturated fatty acids, and hence, we rely on the dietary intake of these essential fats 3,5. Omega-3 polyunsaturated fatty acids are key components of cell membranes, and neuronal membranes in particular, and therefore are necessary for normal brain function 3. Foods rich in omega-3 include certain fish and seafood, some vegetable oils, nuts (especially walnuts), flax seeds, kiwi fruits, and leafy vegetables.

There is general consensus that a dietary deficiency of omega-3 fatty acids in humans has been associated with higher risk of several mental disorders, including attention-deficit disorder, dyslexia, dementia, depression, bipolar disorder, and schizophrenia 3.  Contrariwise, the long-term protective effects of fish against cognitive decline in older adults have been shown repeatedly since increased omega-3 fatty acids are linked to improved cognition (up to three servings of large-mouth fish per week) 2.

Contrary to the effects of diets rich in omega-3 fatty acids, epidemiological studies suggest that diets with a high content of trans and saturated fats adversely affect cognition. Studies evaluating the effects of “junk food” – characterised by high contents of saturated fat and sucrose – have shown a decline in cognitive performance 3.


Folate-Vitamin B9 (or folic acid – the form that is added to foods and supplements) is found in foods such as dark green leafy vegetables (e.g., spinach, broccoli), beans, peanuts, eggs, fresh fruits, liver, aquatic foods, whole grains, yeast, and also in fortified foods and supplements 6. It helps to form DNA and RNA, it is involved in metabolism 6, and its adequate levels are essential for brain function 3. Folate deficiency, mainly caused by low dietary intake, has been associated with physiological abnormalities during development and adulthood and can also lead to neurological disorders, such as depression and cognitive impairment 3.

Body cells face constant threats and one of them comes from chemicals named free radicals 7. A high and continuous amount of free radicals in the body results in a condition called oxidative stress, which may damage cells and genetic material and lead to chronic diseases. The brain, in particular, is extremely susceptible to oxidative damage. One way, amongst others, the body forms free radicals is from the inevitable byproducts of converting food into energy. To defend ourselves from the effects of free radicals, the body draws free-radical fighters from food. These defenders are called “antioxidants”.

Several substances can act as antioxidants and most of them are naturally occurring. The most well-known ones are vitamin C, vitamin E, beta-carotene, and other carotenoids, as well as minerals such as selenium (nuts, cereals, meat, fish, eggs) 3,7. Lipoic acid, flavonoids (cocoa, green tea, citrus fruits, berries, red wine, dark chocolate), phenols, polyphenols, and many more are also included in this broad category. Their presence in food is likely to prevent oxidation or to serve as a natural defence against the local oxidative environment pre-existing in the cell 3,7.

Vitamin E, or α-tocopherol, has been implicated in cognitive performance, since low serum levels of vitamin E were found to be related to poor memory performance in older individuals 3. Vitamin E is abundant in vegetables, fruits, plant-based oils, nuts, seeds and fortified cereals. Specific foods high in vitamin E are sunflower and soybean oil, sunflower seeds, almonds, peanuts, peanut butter, beet greens, spinach, pumpkin, red bell pepper, asparagus, mangoes, avocados 8.

Overall, research has pointed out that the best ‘brain foods’ may be the same ones that protect the heart and blood vessels9. According to Harvard Health Publishing of the Harvard Medical School, amongst foods linked to better ‘brain power’ are the following9:

Green, leafy vegetables
E.g., spinach, collards, and broccoli are high in brain-healthy nutrients such as vitamin K, folate, and beta-carotene. Research proposes that these plant-based foods may help delay cognitive decline.
Fatty fish
Rich in omega-3 fatty acids (as mentioned above), such as salmon, sardines, mackerel, tuna and cod. It is worth mentioning that sources of terrestrial omega-3 are flaxseeds, avocados, and walnuts.
Tea and coffee
Contain caffeine that offers a short-term concentration boost. Apart from that, caffeine might also help solidify new memories.




Nutritional psychiatry: Your brain on food. Harvard T.H. CHAN. School of Public Health.  [Available from: https://www.health.harvard.edu/blog/nutritional-psychiatry-your-brain-on-food-201511168626 ] (Accessed: November 10, 2023).


Dalile B, Kim C, Challinor A, Geurts L, Gibney ER, Galdos MV, et al. The EAT–Lancet reference diet and cognitive function across the life course. The Lancet Planetary Health. 2022;6(9):e749-e59.


Gómez-Pinilla F. Brain foods: the effects of nutrients on brain function. Nat Rev Neurosci. 2008;9(7):568-78.


Rutjes AW, Denton DA, Di Nisio M, Chong LY, Abraham RP, Al-Assaf AS, et al. Vitamin and mineral supplementation for maintaining cognitive function in cognitively healthy people in mid and late life. Cochrane Database Syst Rev. 2018;12(12):Cd011906.


Omega-3 Fatty Acids: An Essential Contribution. Harvard T.H. CHAN. School of Public Health.  [Available from: https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fats-and-cholesterol/types-of-fat/omega-3-fats/ ] (Accessed: November 7, 2023).


The Nutrition Source. Folate (Folic Acid) – Vitamin B9. Harvard T.H. CHAN. School of Public Health.  [Available from: https://www.hsph.harvard.edu/nutritionsource/folic-acid/ ] (Accessed: November 8, 2023).


Antioxidants. Harvard T.H. CHAN. School of Public Health.  [Available from: https://www.hsph.harvard.edu/nutritionsource/antioxidants/#the%20bottom%20line%20on%20antioxidants ] (Accessed: November 7, 2023).


Vitamin E. Harvard T.H. CHAN. School of Public Health.  [Available from: https://www.hsph.harvard.edu/nutritionsource/vitamin-e/ (Accessed: November 9, 2023).


Foods linked to better brainpower. Harvard Health Publishing.  [Available from: https://www.health.harvard.edu/healthbeat/foods-linked-to-better-brainpower ] (Accessed: November 6, 2023).