Glycogen is the stored form of sugar in the body
The body breaks down most of the carbohydrates in the food we eat and converts them into a type of sugar called "glucose." Glucose is the main source of fuel for our cells. When the body does not need to use glucose for energy, it stores it in the liver and muscles. This stored form of glucose is made up of several molecules connected together and is called "glycogen." When the body needs a quick shot of energy or when it cannot get enough glucose from food, it breaks down glycogen to release glucose into the bloodstream and serve as fuel for cells.
Sugar metabolism in the human body
You would be surprised to know that, although sugar has a common path in the body, its final destinations are different and are influenced by the metabolic situation in which you find yourself, varying from one person to another.
Should people with diabetes not drink sugar? Should lactose be removed from all dairy products? Is sugar harmful? These doubts are clarified by better understanding the metabolism of sugar in the human body.
Carbohydrates, familiarly known as sugars, are hydrated carbon molecules whose essential function is to provide energy to the body and form structures. They are made up of units that are usually associated in pairs or disaccharides, which in turn can form branched chains or not. They range from glucose, sucrose (table sugar) or lactose (milk sugar), to cellulose that forms plant structures or chitin that forms the exoskeleton of arthropods, without forgetting the starch present in vegetables and glycogen in animals.
The fate of sugar in the body
Sugar metabolism is complex, so we will only highlight essential points.
Forms of energy storage
1.Starch
In vegetables, carbohydrates develop their energy storage in the form of starch (which is usually present in rice, cereals, etc.)
Fats
On the other hand, animals store energy in the form of fats, which by repelling water allow more energy to be concentrated in less space.Glycogen
Some of our organs store energy in the form of a carbohydrate called glycogen, as occurs in the liver and muscle, an energy that they can access quickly. The muscle will use this easily accessible energy during physical exercise and the liver will use it to release sugar to the rest of the body and thus maintain balanced blood levels.The digestion
In the digestive tract, the different enzymes, salivary and pancreatic, allow us to reduce the complex carbohydrates that we eat, in legumes, pasta and sweets, into smaller compounds that can be absorbed. The final step of this digestion occurs in the wall of the small intestine. This is where specific enzymes break down disaccharides to separate them into elemental units, which can enter cells and pass into the blood. One of these enzymes is lactase, responsible for “breaking down” the lactose in milk.When sugar reaches the blood
The pancreas releases insulin, the hormone that opens the door for sugar to enter cells. Thus, when we consume a tomato pasta dish, all carbohydrates can enter the cells to maintain balance. Once inside, some are consumed for energy, while others are stored as glycogen in the muscle and liver. This is a process that can be adapted and trained, as is the case with elite athletes, capable of storing greater amounts of glycogen in their muscles through specific diets.
Sugars that are ingested in excess, exceeding the body's needs, are used for the production of fats, which store energy.
Important to remember: you do not have to eat sugar or sweet foods so that the body has the necessary daily amount of carbohydrates.
- The brain only feeds on sugar
While other organs can obtain energy from molecules such as lipids or proteins, the nervous tissue only obtains energy from the catabolism of sugars. And it is such an important process that, although the brain only represents 2% of body weight, it consumes 25% of circulating sugar and 20% of oxygen.
The brain is the main sugar consumer in our body
Being the main sugar consumer (about 5.6 mg per 100 g of brain tissue per minute) it is vulnerable to a lack of both oxygen and carbohydrates. It is through this sugar that neurons obtain energy to carry out electrical transmission, to synthesize neurotransmitters and create the myelin sheaths that protect them. In fact, neurodegenerative diseases such as Alzheimer's initially show reduced sugar metabolism in the brain.
The brain alerts you if it needs sugar
When neurons cannot obtain the necessary glucose, autophagy processes are triggered until they use up all their sugar and die. Previously, when the levels fall below what is acceptable, alarm signals are activated that warn the person of the need to consume sugar. These signs include blurred vision, dizziness, sweating, drowsiness, weakness, or hunger, exacerbated by seizures or even coma. At this time the person must consume a sugar envelope or drink a juice, as they contain rapidly absorbed sugars that solve the situation.
Diabetes and sugar
Diabetes is the best studied metabolic disease. Either due to the absence of insulin production (type I diabetes) or due to the insensitivity of the tissues to it (type II diabetes), there is a complete dysregulation of the entire metabolism of carbohydrates, lipids and proteins.
In this disease, the action of insulin does not open the door to sugar in the cells, so glucose accumulates outside and cannot enter. In addition, contradictory messages are sent to the body to consume more sugar and have more availability.
In these cases, the body produces a large consumption of alternative energy sources, such as lipids or muscle proteins. In the case of the brain, lipids are transformed into compounds called ketone bodies that allow it to be nourished, but always requiring a minimum of glucose and being harmful in the long run.
Currently there are ketogenic diets rich in proteins, fats and with the absence of carbohydrates, allowing to burn fat and maintain muscle, but compromising neuronal nutrition.
Does excess sugar indicate that diabetics should not take carbohydrates?
No, this is not so.
In type II (adult) diabetes, sweet foods must be reduced and a balanced and healthy Mediterranean diet must be promoted, without suppressing legumes, cereals, fruits or vegetables.
In type I diabetes (in young people) in which insulin is not produced, a normal healthy diet is recommended without excluding any nutritional group, adjusting the insulin dose to the units of carbohydrates consumed.
The fructose trap
Fructose is the sugar naturally present in fruit. Sometimes many processed foods such as soft drinks, pastries or juices have large amounts of fructose added instead of sucrose and are presented as healthier foods. This occurs mainly in the so-called "foods suitable for diabetics", which by having fructose instead of glucose can bypass insulin regulation.
The metabolism of fructose is slightly different from that of glucose and, although when both are in excess, the production of fats is stimulated, fructose has been implicated in the increase of blood pressure, the accumulation of fat in the liver, the increased triglycerides and bad LDL cholesterol. This occurs because fructose blocks an enzyme that breaks down lipids, as well as facilitates the mobility of triglycerides from the liver to the blood, raising VLDL cholesterol.
Important to note: fructose is always recommended in fruits and honey as part of a balanced and healthy diet, and that it is processed products that contain it in large quantities and should be avoided.