Macronutrients

See also: Zone diet, the three macronutrients

What are macronutrients? What are their functions?

Macronutrients are food principles that must be introduced in large quantities, as they represent the most important energy source for the body. This category includes carbohydrates (or glucides), fats (more correctly lipids) and proteins (or proteins).

Some authors include ethyl alcohol in the macronutrients group; in reality, despite the high calorific value, this substance cannot be considered as such, as it is superfluous for metabolic purposes and devoid of any nutritional value. The attribution of the adjective "macronutrient" to water makes more sense, 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 an abstainer, the macronutrients together cover 100% of the total caloric intake and, broadly, about 90% of the dry food weight. In reference to carbohydrates only, an adult individual consumes about a hundred kilos per year.

All three macronutrients supply the body with energy, but in different amounts and with different biochemical modalities.

Proteins, which have a mainly plastic function, provide the body with materials for the growth, maintenance and reconstruction of cellular structures. Their calorific value is 4 Kcal per gram. Even carbohydrates - which supply energy directly available - 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); for this reason, 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 who would like to deepen the topic.

Macronutrient percentages in a balanced diet

macronutrients,

link to the main articles

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

PROTEIN

Vegetable proteins

Protein requirement

Amino Acids

Essential amino acids

Branched amino acids

Leucine

isoleucine

Lysine

Phenylalanine

Arginine

Taurine

Glutamine

LIPID

Fat requirement

Fat functions

SATURATED FATS

MONOINSATURED GREASES

POLINSATURI FATS

Fatty acids

Essential fatty acids

DHA

Oleic acid

Erucic acid

CARBS

Starch

Cellulose

Dietary fiber

Maltodextrin

dextrins

Fructose

Dextrose

Maltose

galactose

Lactose

PROTEIN

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

LIPID

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

Essential:

ω-6: 5.0-10% of daily calories

ω-3: 0.6-1.2% of daily calories

CARBS

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

NOTES: cholesterol should be taken in the minimum quantity compatible with a correct diet; in the healthy adult 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 fats, which should not exceed 7-10% of daily calories.

As for the distribution of the various types of fat, there are no well-defined standards. In general, nutritionists recommend compliance with proportions that are around 50% monounsaturated, 25-30% saturated and 20-25% polyunsaturated.

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

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

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

Fat digestion

Protein digestion

Carbohydrate digestion