Macronutrients

See also: Zone diet, the three macronutrients

What are macronutrients? What are their functions?

Macronutrients are food ingredients that must be introduced in large quantities, since they represent the most important energy source for the body. Carbohydrates (or carbohydrates), fats (more correctly lipids) and proteins (or proteins) belong to this category. .

Some authors also include ethyl alcohol in the group of macronutrients; in reality, despite the high caloric value, this substance cannot be considered as such, as it is superfluous for metabolic purposes and devoid of any nutritional value. More sensible is the attribution of the adjective "macronutrient" to water, which however, having a zero caloric value, should simply be considered a food.

Whatever the nutritional plan undertaken, the three macronutrients must always appear in percentage and qualitatively correct quantities.

In the diet of a teetotaler, the macronutrients together cover 100% of the total caloric intake and, broadly speaking, about 90% of the dry dietary weight. In reference to carbohydrates alone, an adult individual consumes a hundred of them. pounds per year.

All three macronutrients provide energy to the body, but in different quantities and with different biochemical modalities.

The proteins, which have a mainly plastic function, supply the organism with the materials for the growth, maintenance and reconstruction of cellular structures. Their calorific value is 4 Kcal per gram. Carbohydrates - which supply directly available energy - also supply the organism. they have a calorific value of 4 Kcal per gram. Lipids, on the other hand, release their energy more slowly, but contain it in concentrations more than double (9 Kcal per gram), which is why they are particularly important during rest and fasting.

Below we summarize schematically the main guidelines for a healthy diet, referring to the various links those wishing to deepen the topic.

Percentages of macronutrients in a balanced diet

MACRONUTRIENTS,

links to the main articles

ACCEPTABLE ALLOCATION OF MACRONUTRIENTS in adults (National Academy of Sciences. Institute of Medicine. Food and Nutrition Board)

PROTEIN

Vegetable proteins

Protein requirement

Amino acids

Essential amino acids

Branched chain amino acids

Leucine

Isoleucine

Lysine

Phenylalanine

Arginine

Taurine

Glutamine

LIPIDS

Fat requirement

Functions of fats

SATURATED FATS

MONOUNSATURATED FATS

POLYUNSATURATED FATS

Fatty acids

Essential fatty acids

DHA
Oleic acid

Erucic acid

CARBOHYDRATES

Starch

Cellulose

Dietary fiber

Maltodextrin

Dextrin

Fructose

Dextrose

Maltose

Galactose

Lactose

PROTEIN

10-35% of daily calories, 10-20% according to Italian guidelines

LIPIDS

20-35% of daily calories, 25-35% according to Italian guidelines

Essentials:

ω-6: 5.0-10% of daily calories

ω-3: 0.6-1.2% of daily calories

CARBOHYDRATES

45-65% of daily calories, 50-60% according to Italian guidelines

NOTES: cholesterol must be taken in the minimum quantity compatible with a correct diet; however, in healthy adults it is advisable not to exceed 300 mg / day. The same goes for trans fats - whose acceptable limit is 5 grams / day - and for saturated ones, which should not exceed 7-10% of the daily calories.

As for the breakdown of the various types of fats, there are no well-defined standards. Generally, nutritionists recommend respecting proportions that are around 50% monounsaturated, 25-30% saturated and 20-25% polyunsaturated.

The adequate intake of dietary fiber is between 25 and 35 grams per day.

The caloric contribution from sugars should not exceed 12% (Italian guidelines) - 25% (American guidelines) of the total calories. In any case, they should be consumed sparingly.

Macronutrients cannot be used as such, but require prior digestion: