What is glucose and what functions does it perform in our body?

The world of modern food is a delicate subject, because maintaining balance in the diet with a mostly sedentary lifestyle is, to say the least, a challenge. The human being tends to the sweet and fatty, because it has been seen that foods rich in carbohydrates and sugars activate our brain reward centers in an excessive way.

Therefore, it is no coincidence that in the last 30 years obesity has tripled in the world. The World Health Organization (WHO) estimates that there are more than650 million obese people, something that explains, at least in part, that heart disease is the leading cause of death in Western societies.

Unfortunately, accompanying obesity and on the other side of the coin, we have on the rise disorders such as bulimia, anorexia and disorders of individual image and perception (for example, bulimia reaches levels of up to 3% prevalence in certain sample groups). Neither consuming excess sugar is good, nor worrying about it too much is healthy.

For this reason, the word “sugar” has been stigmatized by certain sectors of the general population in recent years, as its members do not receive the relevant information in the correct way. Here we explain what glucose is from both an evolutionary and functional point of view, and we assure you that you will discover a world more exciting than can be expected at first beyond a medical prism.

• We recommend you read: “How to lower glucose: 10 tips to regulate sugar”

What is glucose?

Glucose is a monosaccharide, that is, a simple sugar that is not hydrolyzed or broken down into other compounds. From a molecular point of view we are facing a hexose, because it has six carbon atoms that act as vertices of its geometric structure, and also before an aldosa, since its carbonyl group is located at the end of the molecule.

It is anatural substance, as it is free in honey and other fruits. This is possible because plants are able to synthesize it from inorganic compounds such as water and carbon dioxide through complex photosynthetic reactions. Naturally, the first stop on this journey should answer the following question: why do these sugars exist in the environment?

The evolution of sugars

We go back to periods before the Triassic, as fossil evidence shows that around this time various insects went from a hematophagous diet (blood-based) to a phytophagous diet (plant-based), in order to avoid competition for food. This, naturally, was a hard blow to ancestral plants, since the predation of the vegetative or reproductive parts of the plants considerably decreased their chances of survival.

The solution? It was time to defend himself. Therefore, plants began to synthesize toxic compounds. Although these types of mechanisms considerably reduce predation, the energy investment by the plant to synthesize and accumulate toxins is astronomical. Be that as it may, the plants lost out whether they defended themselves or resigned themselves to being eaten. Thus, they began to createincreasingly complex morphological structures (the protofruits) to protect their seeds, and at least their offspring were not preyed upon.

Unfortunately, the more energy a living being invests in synthesizing a tissue, the more nutritious content it usually has, and insects ended up being captivated by these fruits. In the end, the solution was clear: if you can’t deal with the enemy, join him. Instead of investing astronomical amounts of energy (for a vegetable, at least) in producing toxins to avoid predation and protective structures, it is much more profitable to resign and accept the evolutionary process: eat me, but I will win too.

Thus, the most widespread hypothesis is that sugars such as glucose arose in nature thanks to the deviation of metabolic pathways in plants in order to produce substances attractive to living beings. This kills two birds with one stone: the vegetative part of the plant is indirectly protected and the animals act as seed dispersers without realizing it.

It is necessary to note that this evolutionary process does not respond to a conscious mechanism on the part of plants: mutations in living beings are random, but the fittest are “chosen” by natural selection to transmit their genes. Anyway, after knowing this information you will surely suspect why, from an evolutionary point of view, a piece of fruit with its colors and sweetness is so striking.

Functions of glucose in our body

With this exciting co-evolutionary story out of the way, it’s time we explored what glucose actually does in the human body. Glucose is a fuel, because after the ingestion of sugars in the diet, this monosaccharide travels through the bloodstream to the different organs and tissues, in order to  provide energy to the cells  so that they perform their functions correctly.

The energy yield of glucose is 3.75 kilocalories per gram, so it is not surprising that it is an excellent driving mechanism for the individual to carry out their biological tasks correctly. In addition, glucose (either ingested directly or as a metabolic product after digestion of carbohydrate products) is stored as glycogen in the liver, a storage center for an energy-rich compound analogous to starch in plants.

It is for this reason that carbohydrates are considered the  main source of energy in humans  and not fats, despite what many people may think. Complex carbohydrates are transformed into simple sugars such as glucose after digestion, and therefore, the intake of carbohydrate-rich foods is directly related to the individual’s blood glucose levels.

The diabetes problem

Speaking of blood, we cannot finish this space without leaving in the inkwell the disorder that brings a large part of the general population upside down: the terms “hyperglycemia” and “diabetes” surely sound familiar, right?

• To learn more:  “Diabetes: what it is, types, symptoms and causes”

Blood is made up of both red blood cells, white blood cells and platelets (45% of its volume), as well as blood plasma (55% of blood volume). This plasma, in turn, is made up of 92% water, 7% vital proteins and 1% mineral salts, sugars, fats, hormones and vitamins. As can be deduced, the blood glucose concentration corresponds to a part of this remaining 1%.

Thus, a “normal” blood glucose concentration is considered to be 70 to 100 milligrams per deciliter, a value thatmay increase slightlyafter ingestion of certain foods. We are facing a minuscule figure if we take into account that an adult human being has an average of 4.5-5.5 liters of blood inside his body.

Unfortunately, a blood glucose concentration greater than 200 milligrams per deciliter, however small it may be, can have devastating long-term effects on the patient: from permanent nerve damage tocardiovascular disease, an extensive series of complications in diabetic patients without treatment shows that any alteration of the homeostatic balance of the human being can be paid dearly.

Insulin is a hormone responsible for regulating blood glucose levels, as it “unblocks” the cells so that the monosaccharide can enter them and they use it as fuel. Unfortunately, diabetic patients either do not produce enough insulin or this hormone does not act as well as it should, which promotes an abnormal rise in blood glucose levels. This disorder is becoming increasingly important on a global scale, with an estimated 1 in 11 adults having some form of diabetes.