Scopriamo i CARBOIDRATI: cosa sono e a cosa servono

Let's discover CARBOHYDRATES: what they are and what they are for

Carbohydrates represent a vast group of substances that play an important energetic and functional role for our body. They fall into the group of macronutrients as our body needs them in significant quantities every day and they are organic compounds made up of carbon, hydrogen and oxygen in a 1:2:1 ratio, with the general formula C n (H 2 O) n .

Based on the organization and chemical structure we can divide them into:

  • Monosaccharides : the simplest units made up of a monomer, examples include glucose, fructose, galactose, mannose;
  • Disaccharides: they are formed by the bond between two monosaccharides such as lactose, maltose, sucrose;
  • Oligosaccharides : they are made up of a number between 3 and 9 monosaccharide units; for example maltodextrins, FOS and GOS;
  • Polysaccharides : they are composed of long chains of 10 or more monosaccharide units, sometimes branched. Examples are starch and glycogen.

These molecules can also be distinguished in relation to the size of the molecule into:

  • Complex carbohydrates : essentially represented by starch and fibre. The first (a compound made up of the union of many glucose molecules) is present in good quantities especially in cereals, dried legumes and potatoes. Dietary fiber is found in almost all plant products.
  • Simple carbohydrates : instead consist of one or two molecules and are mostly sweet in taste, hence the common term "sugars". The most important are sucrose, which is obtained from beetroot or sugar cane, glucose and fructose contained in fruit and honey and lactose contained in milk.

But what is the role of CHO in the diet?

The Italian Society of Human Nutrition (SINU) with its LARN recommends in a balanced diet the intake of approximately 45-60% of calories from carbohydrates, and of these at least three quarters preferably in the form of complex carbohydrates and no more than remaining quarter in the form of simple carbohydrates.

In particular, they recommend that we limit sugar consumption to < 15% of the daily energy intake, including in this category the sugars naturally present in milk, fruit and vegetables and added sugars.

The importance of carbohydrates in the diet derives from the fact that they are absorbed and used by the body easily and without producing metabolic waste, ensuring the cells of all tissues are supplied with glucose and therefore energy. Starch requires some digestive work to be transformed into glucose, and for this reason it is absorbed more slowly than simple carbohydrates which are digested and absorbed more easily. The simultaneous presence of the two types of carbohydrates (simple and complex) in the indicated proportions ensures the body a constant and more prolonged supply of energy over time, such as to avoid sudden changes in the blood glucose level (glycaemia). However, it is important to keep in mind that a food, generally also containing other nutrients such as proteins, fats and fibre, will have a different glycemic index depending on its composition precisely due to the influence that these nutrients have on the glycemic response, determining a variation both on speed rather than intensity.

What is the energy value?

First of all, energy value means the quantity of kcal supplied by one gram of nutrient; for glucose the energy value is equal to 3.75 kcal per gram, for starch it is approximately 4.18 kcal per gram and for dietary fiber approximately 2 kcal per gram. Conventionally, however, an average value of 4 kcal per gram of nutrient is indicated for carbohydrates in general.

Lastly, as we have said, carbohydrates are digested, absorbed and used by our body mainly for energy purposes. Based on the ability of our intestine to digest them we can distinguish the available carbohydrates , this category includes starch and sugars which are digested and absorbed at the intestinal level and thus become usable for metabolic processes; from those that are not available and dietary fibre , which instead reach the colon undigested and here, by our intestinal microbiota, they are partially digested, representing a suitable substrate for the maintenance and development of the microbiota itself.

In the next article we will discover the food sources of this macronutrient and the characteristics that distinguish them!

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