Calories of food

Foods or foods are defined as edible products of various nature and origin that man must take to obtain the energy (calories) and nutritional principles necessary to ensure the normal performance of physiological functions.

Nutritional principles: Classification and functions in the organism

The nutritional principles are the chemical, organic and inorganic constituents, which are found more or less in all foods but in different quantities from one to the other. A food can be said to be complete when it contains all the food principles harmoniously distributed. With the exception of breast milk, there are no complete foods for babies and this is why our body needs a varied and balanced diet.

The various nutritional principles present in foods can be divided into:

Organic: proteins, lipids, glycides, vitamins
Inorganic: water, mineral salts, oxygen

and in:

Macronutrients: proteins, lipids, carbohydrates, can be used by the body only after digestion which transforms them into simple and easily assimilable compounds.
Micronutrients (vitamins and essential mineral salts) introduced in small quantities, are not modified by digestion or absorption and are essential for the regular completion of vital processes (for example, enzymatic reactions)

The functions of the nutritional principles are numerous:

ENERGY FUNCTION: to supply energetic material for the production of heat, work or other forms of energy (proteins, carbohydrates, lipids)
CONSTRUCTIVE and repairing FUNCTION: provide plastic material for the growth and repair of tissues (proteins and minerals)
REGULATING, balancing, protective FUNCTION: providing "regulating" material making metabolic reactions possible (minerals and vitamins)

FUNCTION NUTRITIONAL PRINCIPLES FOOD OR FOOD ENERGETICS Carbohydrates sugars honey, sugar and derivatives, ripe sugary fruit (grapes, figs, bananas) polisaccardi cereals and derivatives (bread, crackers, flours, pasta, rice, etc.), potatoes, floury vegetable foods (chestnuts) Lipids butter, lard, lard, vegetable oils, animal fats, oily fruit (walnuts, almonds), cheeses and fatty meats Proteins meat in general, fish, legumes, dried fruit, eggs

PLASTIC

CONSTRUCTIVE

Mineral salts

Football milk, legumes, cheeses, fish, eggs, rocket, spinach Phosphorus fish, meats, cheeses, eggs, legumes, cheeses, whole grains Iron meat in general, eggs, legumes, fish, dried fruit Iodine sea fish, algae, vegetables grown in iodine-rich soils Proteins meat in general, fish, legumes, dried fruit, eggs

PROTECTOR

REGULATOR

Vitamins A (retinol) red and yellow vegetables, offal, fish liver oil, egg yolk B1 (thiamine) whole grains, legumes, pork B2 (riboflavin) milk, cheese, dairy products, offal and eggs (ubiquitous distribution) PP (nicotinamide) cereals, especially not very refined, dried legumes, meats, eggs, fishery products and offal C (ascorbic acid) Fruit (citrus fruits, pineapple, kiwi, strawberries, cherries, etc.), vegetable tubers (potatoes) and some fresh vegetables (broccoli and similar) D3 (cholecalciferol) liver, fish oils, some marine fish (herring, salmon, sardine), butter, milk, eggs

Foods can instead be classified into seven groups:

Group Foods Nutrients provided To be preferred 1 meats, fish, eggs high quality proteins, iron some B vitamins white meats and fish, without completely excluding eggs and red meats from the diet 2 milk and derivatives calcium, high quality proteins some B vitamins carbohydrates, skimmed milk and low-fat cheeses (ricotta, cottage cheese, lean mozzarella) 3 cereals, tubers and derivatives poor quality proteins, vitamins del
group B whole grains (one or two servings a day) 4 legumes medium quality proteins, iron, some B vitamins at least two to three servings a week 5 Seasoning oils and fats fat vegetable oils (raw not fried) 6 and 7 vegetables and fruit vitamins (especially A and C), minerals, fiber vary at most, at least four portions a day

Energy content of foods

To quantify the energy content of a food, the Kilocaloria (in Italy) or the KiloJoule (one calorie equals 4.186 joules) is used.

The calorific value of a food depends on its composition in nutritional principles:

MACRONUTRIENTS

each gram of carbohydrates provides an average of four kilocalories

each gram of fat provides nine kilocalories on average

each gram of protein provides an average of four kilocalories

MICRONUTRIENTS

they do not provide energy but are equally essential (regulating function)

For this reason, animal fats and oils are by far the richest foods in calories (high lipid percentage); vegetables, on the other hand, provide very few calories (they contain a minimal percentage of carbohydrates while the protein and fat content is often negligible). The consumption of vegetables, by virtue of their high content in fiber, vitamins and mineral salts, is often encouraged without any quantitative or qualitative imposition (each person chooses the vegetables he prefers, taking care to alternate them).

The calories of food "