Value of food

The value of food can be divided into two sub-groups, namely the biological and energy value of food. Energy and biological values are nutritional value, it means the proportion of food to meet the nutritional needs of the human body. For example carrots have a high biological but low energy value. By contrast, a sweet lollipop has a high energy but low biological value (the so-called empty energy).

The energy value of food is the amount of energy that is released by burning nutrients (proteins, fats, carbohydrates) during digestion. The amount of energy that an organism can release from food is a physiologically usable energy value. It is given in units of Joule (J), calories (cal) – older but still used in practice (1 cal = 4,18 J).

Examples: 8 000 kJ = 1 900 kcal
                 1 600 kJ = 380 kcal

Caloric content:
• Fat: 1 gram = 9 Calories

• Protein: 1 gram = 4 Calories

• Carbohydrates: 1 gram = 4 Calories

Table of nutritional values of foodstuffs
100 g food Proteins/g Fats/g Carbohydrates/g kJ
Meat and meat products
beef meat 20,8 7,8 0 668
pork meat – lean 17,3 18,2 0 992
calf 21,8 3 0,5 508
chicken 22,5 3,2 0 521
goose 16 33 0 1533
carp 16 4,2 0 445
fish fillet 16,5 0,4 0 311
sardines in oil 21,2 27 0 1407
porkpie 18 24,4 0 1243
sausages 14 27,7 1,2 1319
ham salami 16,3 13,6 0,1 806
Milk and milk products
half-fat milk 3,2 2 4,4 202
cream – 12 % fat 3,2 12 4,2 567
cream – 33 % fat 2,4 33 2,7 1306
yogurt white 5,7 4,5 9,7 424
kefir 3,3 3,6 1,7 218
low fat curd 19,4 0,3 4,8 437
high fat curd 13,7 12 2,8 735
processed cheese 15,9 18 1,2 970
cheese Niva 19,8 26,5 0,8 1344
cheese Brie 20,2 20,2 1,6 1134
cheese Eidam 30,1 15 1,8 1121
butter 0,5 81,1 0,3 3011
mayonnaise 2 80 3 3058
eggs (100 g = 2 pcs) 13 11 0 655
Fats, nuts
ointment 0,3 99,3 0 3756
bacon 2 85,3 0 3259
oil 0 98,2 0 3650
sweet chestnut 2,3 2,7 42,6 857
almonds 18,6 54,1 19,6 2482
walnuts 15 64,4 15,6 2726
poppy seed 19,5 40,8 24,3 2104
Potatoes, vegetables, mushrooms
boiled potatoes 2 0,2 20,1 370
cabbage 3,3 0,6 7,8 193
kohlrabi 2,1 0,2 6,2 139
cauliflower 2,4 0,2 4,9 118
carrot 1,1 0,2 9,1 172

Nutritional value of food must be according to Act no. 152/1995 Codex on foodstuffs visible on the food packaging. In addition, since 2016, the following should be indicated on the packaging:

Pic 105: Nutritional value of the food

The biological value of food represents the content of nutrients, nutritional factors and their mutual relationship in food, which ensure the preservation and development of all physiological functions in the human body.


In the following text we will focus on the importance of macronutrients (carbohydrates, fats, proteins) in human food.

Proteins - polypeptides composed of more than 100 amino acid residues linked by a peptide bond – specifically spatially arranged. Their daily intake should be 0.75g per kg of human weight for 24 hours. In childhood, pregnancy, breastfeeding, high physical activity and convalescence, their intake should be increased to 2.5 g. They perform a wide range of tasks in the body – from tissue construction, through defense of the organism to coding of genetic information. Thanks to their complex structure, they enable them to perform a wide range of tasks in the body, from tissue construction through nutrient transport to encoding genetic information. Important sources of protein are meat (especially beef), eggs, milk and dairy products, but also soya.

Fats – organic compounds composed of glycerol and higher carboxylic acids (so-called fatty acids). Fats make up about 30% of the body‘s energy needs. They are an essential component of each cellular structure (including nerve cells). They are also an important energy reserve of the organism. Without a certain proportion of fat reserves, women would not start a menstrual cycle. They also provide mechanical and thermal protection of the organism. Their presence in the diet is also important because of the solubility of some vitamins (A, D, E, K). The sources of polyunsaturated fatty acids are mainly walnuts, sunflower, sesame, flax and pumpkin seeds and sea fish (salmon, tuna, mackerel).

Carbohydrates – organic compounds that consist of oxygen, hydrogen and carbon. The daily intake of carbohydrates should be in an average of 200-500g. Overall, they represent approximately 0.3-1% of the human body weight. They cover up to 60% of energy needs, with carbohydrate energy being used first. We recognize monosaccharides (glucose, fructose and galactose), oligosaccharides (consisting of 2-10 carbohydrate units, e.g. sucrose, maltose, lactose) and polysaccharides (more than 10 carbohydrate units, e.g. starch). In excess, carbohydrates are stored (eg in the form of glycogen). Monosaccharides and disaccharides (simple carbohydrates) are simple carbohydrates (mono- and disaccharides) that serve as a fast energy source (but they cannot feed a person for a long time – so-called fast carbohydrates). Foods are referred to as sugars and are particularly glucose, fructose and sucrose.


Vitamins are organic substances important for living even we need them (comparing to macronutrients) in minimal amounts. They are not formed in the animal organism (or only inadequately). Their importance in the human body is mainly in terms of energy management and tissue construction. We know about 20 vitamins, of which 15 are important for humans.

A) Fat soluble vitamins – A, D, E, K

B) Water soluble vitamins – e.g. B1 thiamine, B2 riboflavin, H biotin, B12, etc

Basal metabolism

In addition to energy metabolism, we distinguish basal (basic) metabolism, which means the least amount of energy necessary to maintain vital functions (breathing, digestion, regulation of body temperature, etc.) with complete physical and mental peace, without movement, in sleep. It is clear from this that a person needs a certain amount of energy to provide vital functions even in complete peace (e.g. during sleep).

Basal metabolism and its level are influenced by factors such as:

  • Gender – men have higher BM (+ 5–7%).
  • Age – decreases with age (decrease by approx. 2% in 10 years), child between 6 and 12 years of age uses 50% of energy for basal metabolism.
  • Body surface – the direct proportion of the body surface to the level of metabolism; also associated with thermoregulation / heat loss.
  • Hormonal status, for example during stress the hormone adrenaline increases metabolism.

The total energy expenditure of an average adult over a day, including basal metabolism, can be illustrated as follows:

Pic 106: Total energy expenditure of an average adult over a day

As can be seen from the graph, most of the energy is consumed during the day for basal metabolism. The second highest value of energy consumption is related to movement, i. physical activity that consumes 25-30% of energy. Part of the energy (approx. 8%) is used for the “production” of heat within the framework of thermoregulation (during the winter period one tends to take more caloric meals or increase their amount). Approximately 7% is accounted for specific-dynamic effect of food, which represents the energy spent on processes such as digestion, absorption of nutrients, their transport and utilization in cells.