The nutritional balance
In the light of modern knowledge, we know that the human body, to grow, maintain and carry out its activities, has specifically the nutrients in food.
Ultimately, in the foods of our daily groceries, they contain special molecules called nutrients for the role they play.
Nutrients are classified into the following groups: fat, protein, carbohydrates, vitamins, minerals and water. Of these, the first three are energy, with a calorific value of 9 kcal./gr for fat, and 4 kcal./gr for both carbohydrates that for proteins, while the remaining, although not energy, are very important for the functioning of our body.
That said, the words diet food, food and food security balance have meaning if we consider the relationship between food and the human body. This then is formed by cells, and the cell is fueled not by foods as such, but the nutrients they contain. For this reason, the term "healthy" often replaces the more generic and traditional "food", and then, while the terms of diet, balance and food security describe aspects of the human body, in its entirety, and foods, however the terms of diet, nutritional balance and safety are based on a specific relationship, the one between human cells and nutritious food.
This report can only be understood well with in-depth studies of molecular biology and cytology.
For a simple approach, let us remember the aphorism: "We are what we eat."
This popular saying, which originally was to have a simpler and narrower meaning, now has scientific value!
In simple terms, it means that the nutrients of food, besides giving us the energy we need, the constituents of our bodies are. For some hints about it, read about it in Appendix the role of DNA in the process of protein synthesis.
Ultimately, there is a complete food (milk lacks iron, no this), and, on the other hand, no food is absolutely essential, because you can always find one or more foods that provide the same range of nutrients.
So, as we have already said about the food balance, a proper diet, select and dispense food meal so that during the day is not the case the absence or shortage of a necessary nutrient.
In the "Food Balance" We've talked about energy needs and representation of total daily calories in the three-derived protein percentages, glucose and lipid.
That said, the problems are two:
A. You must know what and how many nutrients is made every food we eat
B. You must know how many and what nutrients are needed in the body various physiological conditions, namely the energy needs.
The answer to the first question is provided by the "food composition tables", published in Italy by 'INRAN (National Institute of Research on Food and Nutrition). These tables provide information on the chemical composition of foods and their energy value (% of each nutrient contained in the food in question, and energy value is expressed in Kcal / gr. That in KJ / gr.), And their extract, sufficiently significantly, it is given in Appendix to these Notes.
Regarding the relationship between the human organism and cell nutrients, we recall at this point that the constituents of the human body are as follows: 60-70% water, about 15- 17% fat, 15-19% protein, just 1% of carbohydrates (because "burn" very easily), about 4% of mineral salts, and small but important amounts of vitamins. We find that the same groups that were formed nutritious food.
Ultimately, at the molecular level, the nutrients of food, and the constituents of the human body are the same: different is only their composition, not their nature. Obviously, the nutrients contained in food are partially processed in the constituents of the human body and in part are, as a result of complex digestive and metabolic processes, "burned" to produce energy.
Finally, they said essential nutrients are those that the body is unable to synthesize, and which must therefore be necessarily introduced with food; they are water, all the mineral salts, a good part of the vitamins, nine of the 26 amino acids that make up proteins, and two unsaturated fatty acids, linoleic acid, also known as omega 3, and linolenic acid, also called omega 6.
Food composition tables
For the second problem, the solution is supplied from the use by nutritional experts, from the table of L.A.R.N., namely the "levels recommended intake of energy and nutrients for the Italian population". The RDAs are recommendations of 'INRAN about the amount of energy and specific nutrients, which the Italian population, broken down by age groups and in both sexes, should be introduced to maintain a good state of health. Ultimately, L.A.R.N. They represent an excellent support to the solution of the energy needs of a person.
Relations between human cell and metabolism of nutrients
Finally, we give below some mention of the relationships between human cell and metabolism of nutrients.
The cell is one of the most complex things Universe. A didactic image is provided in the Appendix.
After the phases of digestion and assimilation of food, it follows the metabolic process of nutrients by the cell. During the process of digestion, nutrients are extracted from foods, processed enzymatically and by different routes, depending on the case of carbohydrates, proteins and fats into simpler molecules, directly usable by cells. The residual undigested food, especially fibers, they pass into the colon, which has the function to expel them.
The digestion of carbohydrates and proteins occurs in the stomach and intestines, that of fat, however, exclusively in the intestine, by specific enzymes.
Enzymes are highly selective biochemical catalysts, which greatly accelerate the processing speed of the molecules. For selectivity, it is meant that each enzyme accelerates the processing speed for more than a single, specific nutrient.
Thus, for example, different species of amylase transform the macromolecule starch carbohydrate (a polysaccharide), in disaccharides lactose, sucrose and maltose, which in turn are cleaved by the enzyme lactase, sucrase, and maltase in the monosaccharides glucose, fructose and galactose, directly usable by the cells.
Similarly, the proteins are divided over the constituent amino acids, the enzymes pepsin, trypsin, chymotrypsin, and others.
The fats, finally, composed of triglycerides, by means of the enzyme lipase, and with the aid of bile salts, are transformed into glycerol and fats, both saturated acids, or unsaturated, also usable directly from the cells. Whatever the road traveled, however, the ultimate goal is the same: to transform the large molecules contained in food into smaller molecules, can be directly used by the cells.
Such cells are structured in different types of organs and tissues, which use the final nutrient according to the needs of each of them, which are not the same. For example, brain cells use glucose produced by the liver, while the muscles use glucose from the processing of carbohydrates for short and intense efforts, and mostly fatty acids from the body's fat reserves for the long-term work. Nutrients not used are converted into fat, and put on reserve; so when we eat too much we increase the weight!
We finally got to the point to describe in what way, certainly fascinating, the cell uses this variety of simple molecules, which include the nutrients that are needed.
The metabolic reactions are very numerous, but fortunately most of them are attributable to a few basic mechanisms, the interpretation of which allows to enunciate these general principles: All cells in the same manner transform the chemical energy of the nutrients into energy usable by the body human to do work. The various organs and the fundamental structures of the human body are synthesized in the same way, namely with common mechanisms, starting from simple nutrients used by the cells. The cells are renewed with the same mechanisms.
When fully operational, in the body there is a certain balance (equilibrium orthostatic). For example, the blood sugar level is included in a certain range, and so the concentrations of important ions such as Na +, K +, and still others. Meals tend to break this equilibrium. Speakers then two signaling systems, that of neurotransmitters, and endocrine, that indicate how and where to distribute the nutrients produced by the cells.
Finally, it should be borne in mind that for DNA work is carried out protein synthesis. In the genetic code of DNA it is already written "how" and "when" the proteins must be synthesized starting from their constituents, amino acids, also called "the building blocks of life." The so-synthesized proteins are then transported and distributed where they are needed for the maintenance and body growth of the human body.