The Influence of Diet on Brain Function

A number of people are convinced that individuals who "work with their heads" do not have as high nutritional demands as their physically active counterparts. However, the opposite is true.

The brain is the biggest consumer of energy among all the body's organs. Although it accounts for approximately 2% of the body weight (1300 - 1400 g), it consumes a fifth (20%) of the energy that a person receives for its activity. Since the vast majority of brain cells are nourished by glucose, it seems more appropriate if the concept of diet is based on the principles of high-carbohydrate diet. With increasing brain activity, energy consumption naturally increases as well (when specific centers of the brain are put into action, the blood vessels in them expand, the blood supply increases, and thus the glucose supply).

Since 20% of the total daily energy need is indeed a high value, it is reasonable to start addressing the energy balance when adjusting the concept of diet. Generally speaking, in caloric restriction, the body is forced to draw energy sources from its own reserves, which poses a risk that the brain might lack enough sugars in its effort to perform at a higher level. Even though the body knows how to break down glycogen in the muscles and liver into simple sugar, most people in a negative energy balance will experience decreased brain activity.

An important aspect for maintaining stable brain performance is not just sufficient calories but primarily the quality of energy sources. While complex carbohydrates from whole grains or legumes ensure a steady supply of glucose, simple sugars from industrially processed foods cause sharp fluctuations in blood sugar levels and subsequent mood swings and attention fluctuations. [1]

• Carbohydrates in the range of 45-60% of the total energy intake,
• Proteins approximately 15-20%,
• Fat in the range of 20-30%.

At this point, it is necessary to highlight a very important and often addressed situation in practice: Even though the brain needs sugar for its function, its excessive consumption causes a strong form of addiction. Higher levels of glucose lead to the activation of the same areas of the brain that are activated after a dose of alcohol or hard drugs. [2] The brain is very sensitive to a drop in its main energy source (glucose), but a decrease in blood sugar levels most commonly occurs after overeating sugars, respectively during frequent and repeated consumption of sugars. When a sudden surge of sugar sources is consumed, blood glucose levels increase rapidly, followed by a rapid decrease (alternating hyperglycemia with hypoglycemia). This fluctuation in blood glucose levels leads to typical symptoms of addiction - a decline in performance, mood swings, fatigue, lack of concentration, and drowsiness.

Some low-carbohydrate diets offer an interesting advantage by leading metabolism to increased use of ketones (products of fat metabolism) as the primary energy source. Thus, they eliminate the fluctuation in blood sugar levels and the associated increased fatigue and loss of concentration. However, these methods are more challenging to implement in practice, and not everyone can incorporate them into their lives in the long term. [3]

It is therefore appropriate to take into account individual differences. While moderate restriction of carbohydrates may benefit some people, others may function better on a regimen with a higher carbohydrate content. It always depends on genetic predispositions, the level of physical activity, and overall lifestyle.

Moreover, there are several nutrients that have a well-proven impact on brain function:

- Omega-3 fats.
These fatty acids are a key component of brain structure. Their adequate intake increases cognitive abilities, including resistance to stressful situations. [4]

- Lecithin.
It is composed mainly of choline and inositol. Choline is converted in the body into acetylcholine, which transmits nerve impulses in the brain. We can ensure sufficient choline intake by consuming nuts and seeds, or unfiltered oils pressed from them at low temperatures. [5]

- Vitamins B complex.
Mainly B1, B2, B6, B9, and B12. They are essential as a supportive factor in the synthesis of neurotransmitters and the formation of neuronal processes and their protective sheath. [6]

- Adaptogens.
Their significance lies mainly in their ability to increase mental performance above average and prevent significant fluctuations during their use. [7]

- Serotonin.
It is nicknamed the "happiness hormone". It acts as a neurotransmitter, i.e., a carrier of nerve impulses. Its sufficient concentration is important for maintaining wakefulness. We do not receive this substance through diet; the body must create it. It requires a number of other substances (precursors) - the key being the amino acid tryptophan, and others include minerals calcium and magnesium. For those interested in a holistic approach to nutrition and health, the most crucial information is that approximately 80% of serotonin in the body is produced by gut microbiota activity. Instead of trying to increase the consumption of food rich in the serotonin precursor tryptophan (meat, fish...), which may result in metabolic imbalance, it is considerably more sensible to aim for proper nutrition of intestinal microorganisms, with the goal to support its diversity. This essentially means trying to ensure a higher proportion of not only soluble forms of fiber but also insoluble (e.g., in the form of resistant starch). [8]

- Stimulants.
These should be handled very cautiously, because:
- they have only short-term effects,
- they create addiction,
- their withdrawal results in a decline in nervous system activity.
The most popular is caffeine and its derivatives. Generally, if it is not absolutely necessary to forcibly stimulate the brain from reserves for a short time, it is wiser to avoid them. [9]