The nutrients They are all the substances that a living being needs to carry out its metabolism. Metabolism is the physicochemical processes that occur at the cellular level and allow substances obtained from the outside to be changed into chemically different substances that the body needs for its growth and survival. Each species needs specific nutrients for its metabolism.
The oxygen it is an indispensable element of metabolic processes in aerobic organisms such as animals and humans. We do not usually consider oxygen a nutrient, however, it is considered that way from the point of view of botany and ecology, since it is the necessary substance so that all other nutrients can deliver their energy to organisms.
They are called essential nutrients to those that cannot be manufactured by the human body, that is, it is necessary that we consume them with meals.
The nutrients described below are usually mixed and combined in food, in various proportions, and are rarely found in its pure state.
Examples of nutrients
Protein
Also called protids, they are molecules made up of chains of amino acids.
Proteins are classified into:
- Holoprotein (holopeptide or simple protein). It has a unique amino acid sequence. Among the holoproteins are nucleic acids, that is, elements that make up DNA.
- Heteroproteins (conjugated proteins). They are molecules that have a protein and a non-protein part, which is called the prosthetic group. Depending on which prosthetic group is, they are classified into:
- Phosphoproetins. Prosthetic group: phosphoric acid. They are enzymes, like the different types of casein.
- Glycoproteins. Prosthetic group: glucid (sugar). They can also be enzymes but also hormones and fulfill other functions. Immunoglobulin is a glycoprotein.
- Lipoprotein. Prosthetic group: lipid. They are in the membranes of the mitochondria.
- Nucreoproteins. Prosthetic group: nucleic acid. They are ribosomes or chromosomes.
- Chromoproteins. Prosthetic group: various metals, such as iron. They serve as oxygen stores (myoglobin), in the transfer of electrons (cytochromes) and various pigments (hemoglobin, rhodopsin).
- Derived proteins. They are those that are formed from the denaturation of the previous proteins.
Protein characteristics
- Acidity stabilizers. It can behave as both acids and bases, since they can take or remove electrons. That is why proteins make it easier to maintain the pH that the body needs, modifying as necessary.
- Electropheresis. They have electrolytic capacity.
- Specific. Each protein has a specific function. That is why one cannot replace the other.
- Stable. They are molecules that remain stable in aqueous media.
- Soluble. Its solubility is achieved through polarity.
Proteins are used in
- Muscles. They stimulate the muscles to contract.
- Antibodies. They are part of the immune system.
- Energy. Although it is not their usual use, in the absence of carbohydrates they can be used for energy (4 kilocalories per gram of protein)
- Fabrics. They form support tissues by integrating fibers, for example collagen. They are the raw material of the muscles.
Where are they found?
Proteins are found in large quantities in meats, eggs and dairy. They are also present but to a lesser extent in dried fruits, cereals and vegetables.
Carbohydrates
Carbohydrates, carbohydrates or carbohydrates are biomolecules made up of carbon, hydrogen and oxygen. In the bodies of living things, carbohydrates fulfill structural and energy storage functions.
As food, they are a readily available source of energy (unlike fats, which also contain energy but require longer processes to release it). Each gram of carbohydrate provides 4 kilocalories (energy).
Classification of carbohydrates (according to their structure)
- Monosaccharides. Formed by a single molecule.
- Disaccharides. Formed by two monosaccharide molecules, joined by a covalent bond (glycosidic bond).
- Oligosaccharides. Made up of between three and nine monosaccharide molecules. They are usually bound to proteins, thus forming glycoproteins.
- Polysaccharides. Formed by chains of ten or more monosaccharides. The chains may or may not be branched. In organisms, they fulfill structure and storage functions.
Where are they found?
Carbohydrates are found in a higher proportion in foods based on flours (glycogen) and vegetables (starch).
Lipids
Contrary to what we usually believe, fats and oils they are not necessarily harmful to the body. On the contrary, there are oils that are essential for the proper functioning of our body.
Lipids that are in solid state at room temperature and are of animal origin are called “fat”, while “oil” is called lipids that are in liquid state at room temperature, and that are mostly of vegetable origin.
Lipid characteristics
- Insoluble in water: that is why water and substances such as oil do not mix.
- Soluble in organic solvents: fats can dissolve in benzene, ether, chloroform, alcohol and other organic substances. For this reason, when cleaning kitchens, alcohol is used to remove grease from surfaces.
- They have a lower density than water: o small oil bubbles float in liquids such as soups and broths.
- They are mostly slippery and shiny on the surface.
Lipids offer a reliable and storable source of energy. For every gram of fat you get 9 kilocalories, more than double what you get from a gram of protein or carbohydrates.
In addition, lipids can be used by the body to create tissues that insulate from the cold, protect organs, participate in the absorption of vitamins and the synthesis of hormones, form cell membranes and wrap nervous tissue.
Where are they found?
Fat or lipids are especially concentrated in vegetable oils (they are 100% lipids), butter, achuras (viscera) and bacon.
Vitamins
Vitamins are necessary to catalyze physiological processes in which they intervene directly or indirectly. Vitamins are not used for get power. They are involved in the formation of enzymes.
Compared to other nutrients, the necessary amounts of vitamins are minimal, and are measured in milligrams. However, these small doses are essential to avoid serious vitamin deficiency diseases (hypovitaminosis).
Among the vitamins are:
- Vitamin A (retinol). Fat soluble. It participates in vision, the immune system, the maintenance of epithelial cells, and growth from embryonic stage to adulthood.
- Vitamin B. Water soluble. It is a vitamin complex that includes substances such as Thiamine (B1), Riboflavin (B2), Niacin (B3) among others. This complex collaborates in multiple functions, such as growth, the breakdown of other nutrients, the creation of new cells, etc. They are found in eggs, dairy, green leafy vegetables, fish, chicken, and beef.
- Vitamin C (ascorbic acid). Water soluble. It participates in multiple metabolic reactions and prevents scurvy disease. Although humans cannot synthesize it (it is an essential nutrient), most plants and animals can, so it is easy to include it in the daily diet through fresh food (not packaged or dried).
- Vitamin D (calciferol). Fat soluble. Prevents rickets. Regulates the passage of calcium to the bones. It is found in milk and eggs.
- Vitamin E (tocopherol). Fat soluble. They work as antioxidants, protecting fatty acids from the body.
- Vitamin K (anti-hemorrhagic vitamin). Fat soluble. They participate in blood clotting and generate red blood cells.
Mineral salts
Salts are ionic chemical compounds (made of anions and cations). Mineral salts are inorganic salts. These are not used to obtain energy.
Salts are found associated with other molecules in the human body, such as phosphoproteins and phospholipids.
Features
- Structural. Calcium, phosphorus, magnesium and fluoride are part of the structure of bones and teeth.
- Cell hydration. Salts participate in osmosis, that is, the process by which the difference in salt concentration produces the transit of water through a membrane. In this case, it is the cell membrane. Salts can cause water to enter or leave cells when necessary.
- Metabolic. Chromium enables insulin to function, selenium prevents lipid oxidation, and sodium enables glucose to be utilized.
- Immunological. Zinc, selenium and copper participate in the immune system.
Food: Mineral salts can be found in a variety of foods:
- Calcium. In milk and its derivatives, in nuts and legumes.
- Match. In meat, fish, milk and legumes.
- Iron. In red meat, legumes and nuts.
- Fluorine. In the sea fish.
- Iodine. In fish and iodized salt.
- Zinc. In meat, fish, eggs, whole grains and flours, legumes.
- Magnesium. In meat, some vegetables, legumes and vegetables, in fruits and milk.
- Potassium. In meat, dairy, fruits and some vegetables.