The term "sugar" is commonly used to refer to a whole class of molecules. Fructose, sucrose, maltose, lactose, glucose, starch, dextrose are all types of sugar. The main consumer of sugar in our body is the brain. For him, glucose is the main source of energy, and the brain consumes it like a car's fuel. To put it simply, all carbohydrates, once in our body, are converted into glucose by the brain. If it's difficult to speak, then glucose is processed into pyruvate, and that into acetyl SKoA, which is sent into an even more complex reaction with the release of energy.
When sugar enters our body, the taste buds of the tongue react to it first. They send a signal to the cerebral cortex, where different departments are responsible for different tastes: bitter, salty, spicy, sweet. The taste test activates the brain's reward system, the so-called pleasure center. He's excited. Communication, sex, or play can have the same effect on him, but the simplest artificial way to “please” this part of the brain is to eat some sugar. It is the reinforcing system that is responsible for the production of dopamine.
Dopamine - what's in this word? It is a neurotransmitter or neurotransmitter, the so-called biologically active chemicals that transmit impulses. In addition to dopamine, there are several of these in the command of our brain: serotonin, for example, or taurine are also neurotransmitters. They all eat glucose. When it is not enough, neurotransmitters are not produced, and communication between neurons is disrupted. Neurotransmitters control different directions. Dopamine is responsible for locomotor activity, thinking, emotions, and endocrine functions. Dopamine receptors are unevenly distributed throughout the anterior part of the brain. Alcohol, nicotine, or heroin have a very strong effect on dopamine. And sugar too, albeit not as radically as its narcotic counterparts. The production of dopamine is important for the body - if it suddenly begins to be released in smaller quantities, we will lose motivation, we will feel tired and sad. Moreover, many diseases, including depression and bipolar disorder, are triggered by a deficiency in serotonin and dopamine. But this does not mean that the absence of a couple of chocolates a day will make someone a potential client of a psychotherapist. Our brain receives all the necessary supply of glucose from the usual daily food. That's why dopamine is finicky. You've probably noticed that the same type of food quickly causes irritation. This is a dopamine trick - he pays special attention to new or unusual tastes, and old ones quickly become boring, and dopamine levels slowly decline. Thus, the brain is trying to align our nutrition: through a variety of foods, we get more vitamins for the body.
Glucose is either consumed for energy or converted into glycogen and stored. This supply is needed in case a person makes too much of a gap between meals. The reserves of glycogen are not so great, they are enough for about a day. In order to avoid an excess of glucose, a blood-brain barrier is needed. In fact, it protects the nervous system from foreign agents, but it has a special "sugar gate". They "open" when glucose is needed and "close" when there is enough glucose. So, if the brain is "full" of sugar, the extra chocolate will not help it to work faster - the gate will be closed. But the evolutionary model is not easy to change. Our brain is so "happy" about glucose because it gives it the energy it needs. In the days of the cavemen, it was not easy to get it, and the brain still perceives glucose as a scarce commodity, not getting used to its presence on the shelf of every supermarket.
It is impossible without sugar, but the harm it can cause to the body is not limited to a couple of extra pounds. Sugar acts like a drug on our brains, and these are not horror stories from diet sites. Scientists from Aarhus University in Denmark conducted an experiment in 2019 and proved that sugar is addictive (an article about this was published in Scientific Reports). However, pigs were chosen as test subjects, not humans. The fact is that people, complex and contradictory creatures, could not ensure the purity of the experiment, because in their brain the level of dopamine fluctuates under the influence of too many factors: the hormone of joy is produced after meeting with someone, playing an exciting game on the phone, etc. Choosing pigs reduced the bias in the results. Their brains are more complex than those of a rat, and their size is ideal for visualizing brain activity. For 12 days, the pigs were given two liters of sugar water a day, and at the same time, what was happening in their brains was recorded using MRI. The team of scientists found significant changes in the dopamine and opioid systems, with the second, which is responsible for the chemistry of well-being and pleasure, was activated after the first intake of the sugary drink! The experiment confirmed that sugar affects the reward system in the same way as drugs: neurotransmitters - dopamine and opioids are released. Do you know the desire to eat a chocolate bar in moments of heavy sadness? It's natural because the brain offers an easy and quick way to get almost instant joy.
The rats, with which American scientists from Princeton University worked in 2008 as part of another experiment, also showed all signs of addiction on a diet high in sugar, up to and including withdrawal. Rodents, in addition, showed a propensity for alcoholism and became dependent on opioids, that is, like pigs, they became hostages of the hormone of happiness. Scientists gave some rats a taste of both sugar and the drug, and upon re-selection, the test subjects were still inclined in favor of sweets.
Book cover Why My Brain Isn't Working? Dr. Datis Kharrazyan, expert in functional medicine
True, such experiments in the world of science are often controversial. Scientists from the international consortium NeuroFAST believe that "glucose-related disorder" can hardly be equated in diagnosis with a narcotic. They conducted research in rodents and insist that any eating disorder can only be classified as a psychological phenomenon.
But if addiction is not so dangerous when it is controlled, then disruption of brain activity can lead to truly unpleasant consequences. Scientists from the University of California in 2012, conducting a study on animals, proved that an excess of glucose is directly related to premature aging of cells. And a team from the University of Montreal and Boston College had confirmed three years earlier that too much sweets can lead to cognitive impairments in the brain. In 2018, colleagues from British and Chinese universities published a study in Diabetologi that experimentally confirmed this problem. Observing 5189 people over 10 years, scientists have found that brain dysfunctions are indeed more intense in those with a sweet tooth than in those experimental subjects whose blood sugar levels are closer to normal. A diet high in sugar can also increase your risk of developing Alzheimer's disease. It is even sometimes called "type 3 diabetes", hinting that excess sugar can trigger the disease. In this case, the brain actually becomes the target organ for damage.
Dopamine neurons of the midbrain in the substantia nigra. www.frescoparkinsoninstitute.com
Our body is like a car, whose main fuel is sugar. The brain, with its complex structure, is the most energy-intensive organ, accounting for half of all sugar energy. He needs glucose so badly that he is ready to get it from other sugars - fructose, found in fruits, and lactose, milk sugar. If you've ever tried to critically limit your intake of sweets, then you know how challenging it can be. Irritability, mood swings, a feeling of "fog" in the head, fatigue - all these symptoms accompany a lack of sugar, if the brain is already used to it. This is due to the fact that a sweet muffin or soda leads to an increase in blood sugar, and then to a sharp drop. It turns out that the more sugar you consume, the more noticeable its absence will become.
Neurotransmitters in the brain help maintain a stable mood. Sugar consumption stimulates the release of not only dopamine, but also serotonin, which is responsible for improving mood. According to Dr. Datis Kharrazian, an expert in functional medicine and author of the book Why Is My Brain Not Working ?, we have limited reserves of neurotransmitter, and the constant activation of serotonin pathways can lead to their depletion, and this, in turn, provoke the development of symptoms of depression …
When motorists come to a gas station, they often say: “Mine drives the 95 best,” for example. Our brains work more efficiently on glucose. And he is very vulnerable if she is missing. Lack of sugar immediately affects mental performance. To stay “in shape”, the adult brain needs 62 g of glucose per day. This is a little, less than 250 kcal. Three tablespoons of honey contains all the required dose. Refusal of glucose is fraught with serious consequences, so even with the strictest diet, it is better to monitor the amount of glucose consumed, it must be in the diet. But don't get too carried away with sweets. Even if now they make the brain happier, someday later this artificial happiness will still “backfire” on the body.
Brain neuroimaging. Photo: Pete Saloutos / Corbis, www.theguardian.com