If the brain needs sugar to work, why do we have to stop eating it?

As the Italian writer and chemist Primo Levi said in his book of 1975, the periodic system, "The fate of wine is to be drunk, and that of glucose, to be oxidized". That's right, not in vain this organic compound is the main fuel that provides energy to the cells of the organism. Also to the neurons of our brain which, like that of all mammals, needs a constant supply of glucose to function.

Still, who recommends reducing free sugar consumption (which is added, not naturally found in some foods such as fructose, fruit, or lactose in milk) below 10% of the total caloric intake of the day , and even encourages this consumption to fall by 5%, as it "would produce additional health benefits." This year also the food industry has been introduced into a process of reformulating its products to reduce these sugars, in addition to salt and saturated fats. Why is it that if glucose is fundamental to brain functioning it doesn't help that we eat sugar?

How Sugar eats the brain

Glucose — The term comes from Greek and means something like "must sugar" — is an organic compound very common in nature, a form of sugar formed by large molecules that, through what is called catabolic oxidation, is transformed into molecules Smaller and simpler, a process that releases an important amount of energy that is used to carry out the set of chemical and physicochemical reactions that take place in all the living cells of the organism, what is known as metabolism.

In particular, "the brain consumes 5.6 milligrams of glucose per 100 grams of brain tissue per minute," explains Ramón de Cangas, of the Spanish Academy of Nutrition and Dietetics. In the brain of an adult individual, he adds, the greatest demand for energy comes from neurons, demanding tastes : For them glucose is paramount, because unlike the common cells, which also obtain energy from other sources, the Neurons are practically dependent on this substance. Therefore, despite the fact that the brain accounts for less than 2% of the body weight, it spends up to 20% of the energy of the total glucose that the organism manufactures: it is its main consumer.

where we get glucose

Glucose, therefore, is an essential component for life, and in particular for the correct development of brain functions. However, even if it is a simple sugar or monosaccharide, do not have to take sugar or sweet foods for the organism to have the necessary amount, an argument that the food industry frequently uses to justify the inclusion of sugars in the products they market.

All the foods that we eat end up being converted into glucose, it is special carbohydrates: cereals, tubers, legumes, dairy products, fruits and vegetables

"Indeed, if a person adopts a sugar-free diet, it would not be a problem: the organism has several mechanisms to obtain glucose," says Cangas. "In addition to obtaining it through feeding, our body can synthesize it from glycogen, a polysaccharide stored in the liver and, to a lesser amount, in the muscles. Glucose is also generated from fat disposal products called ketone bodies, which, in situations of hypoglycemia (low blood sugar), can supply that deficiency. Other sources of energy are fatty acids. "Fat is stored in the form of triacilglycerides (a molecule of glycerol and 3 of fatty acids). In humans fatty acids can not originate glucose but glycerol yes, although in minimal quantities.

The fair amount: neither too much nor too little

In short, all the foods that we eat end up being reconverted, to a greater or lesser extent, in glucose, ie, in energy for the organism. In particular, the most easily converted type of food is the group of carbohydrates. These include free sugars that are added to countless products, but also many others, such as cereals, tubers, legumes, dairy products, fruits and vegetables. If we take a healthy diet and our organism works well, there's nothing to worry about: The glucose intake is assured, even if we don't drink cupcakesanymore. The evolution of having resources to obtain the main contribution of cellular energy has already been occupied.

But, as you know, the organism can fail for many reasons, also in terms of obtaining glucose. When the contribution is not necessary, that is, when the amount of glucose in blood is excessive or insufficient, it produces, respectively, hyperglycemia and hypoglycemia.

Diabetes is one of the most widespread causes of this dysfunction, and is due to insulin resistance presented by those affected by this disease. Insulin is the hormone that regulates the amount of glucose in the blood. If this does not work, you can trigger both hyperglycemia (more often) and hypoglycemia, and the consequences are all negative. " high levels of permanent blood glucose," explains de Cangas, "may cause damage to various organs of the body, such as the retina, kidney, arteries, or nervous system. On the other hand, low levels of glucose (for example, those that cause uncontrolled type 1 diabetes) can lead even to a diabetic coma and to the death of the patient. "

When the brain asks us for food, it's sending us an SOS

If glucose is scarce there are several dysfunctions and pathologies, as evidenced by a study conducted by researchers from universities and research centers in Germany and the United States. "Glucose metabolism provides fuel for the physiological function of the brain through the generation of ATP — adenine triphosphate, the star molecule in the process of obtaining cellular energy in chemical reactions — the basis for Cellular and non-neuronal cell maintenance, as well as the generation of neurotransmitters, "he says in the study.

"If glucose metabolism is altered — says de Cangas — several neurological alterations can arise, as well as obesity, type 2 diabetes, dementia, or Alzheimer's: Precisely, one of the earliest signs of this disease is the reduction of Brain glucose metabolism. "

It should be noted, adds De Cangas, that "if neurons can not get the glucose they need, it can trigger even a process of cell death by autophagy; By not having the food they require to function, these brain cells get the energy from themselves to death. "

Therefore, when glucose levels are below the necessary, neurons activate a series of alarm signals sent to the body as a whole: vision problems, irritability, anxiety, sweating, dizziness, drowsiness, confusion, Weakness, hunger... A collection of messages that cause the person to correct that lack of glucose by eating food. If glucose does not increase, seizures, fainting, or even a coma may result, which could end with a neuronal death. On the other hand, the symptoms of hyperglycemia (that is a concentration of blood sugar higher than 180 milligrams per deciliter, mg/DL) are an excessive thirst, headache, problems in concentration, blurred vision, frequent urination and loss of Weight.

"On its ascending path, which leads to balance and thus death, life draws a handle and nests in it," says Primo Levi on the process by which glucose is oxidized to become energy. Without a doubt, this biomolecule is a good example of the organism's wonderful ability to adopt the most intricate ways to cling to existence.