Understanding Nutrients: Types, Functions, and Importance
Types of Nutrients
• INORGANIC NUTRIENTS – Water – Minerals
• ORGANIC NUTRIENTS – Carbohydrates – Lipids – Proteins – Vitamins
Food and nutrients:
Food provides us with the nutrients necessary for our bodies to grow and carry out vital functions. These nutrients include biomolecules (sugars, lipids, vitamins, proteins) as well as minerals and water.
Sugars (Carbohydrates)
These are energy-giving substances found in many foods that we eat on a daily basis.
There are two groups:
- Simple sugars: have a sweet flavor and are crystalline and soluble in water. Monosaccharides and disaccharides belong to this group.
- Complex sugars: are neither sweet nor crystalline but are made up of many simple sugar molecules joined together. The most important glucido is starch (amylose).
Lipids
These are a variety of very different substances, which are insoluble in water and have an oily appearance. These are different groups within lipids:
- Fats: are high-energy-giving molecules which, because of their chemical composition, are classified into:
- Saturated fats: usually from animals
- Unsaturated fats: almost always from vegetables and usually liquids, which is why they are called oils.
- Membrane lipids: make up the membranes of cells and cell organelles.
- Regulatory lipids: include some vitamins and hormones.
Proteins
- They are made of basic units called amino acids.
- There are 20 different types of amino acids.
- There are 8 essential amino acids that our body cannot synthesize, and therefore we have to add them to our diet.
- These nutrients are the most important structural molecules. They are formed by single molecules called amino acids, joining together to make proteins. The body uses amino acids, which it can obtain from protein-rich food. In our diet, we can have animal or plant proteins. The animal proteins have a higher nutritive value for us.
Think of examples of food rich in:
- Animal proteins: meat, fish, cheese, eggs, milk.
- Plant proteins: leguminous plants (beans, green beans, peas), cereals, bread.
Minerals
These are inorganic substances that have different functions in our body. Some are structural, making up an important part of our bones and teeth, and others allow organs to function correctly and intervene in the regulation of cell metabolism.
Minerals are present in variable quantities in all our food, especially in fruit and vegetables, and some of them are in the water we drink.
Common salt is vital for our development, although the sodium it contains can contribute to water retention in our body.
Water
Water is the most abundant molecule in our bodies (it makes up about 63% of our body mass).
It acts as a solvent for most of the other nutrients, which is vital for the body to carry out metabolic reactions. One of the functions of water is to act as a carrier for substances between different parts of the body. It is also used to regulate temperature.
We need to consume 2.5 liters of water every day. We eliminate it through urine, breathing, sweat, and feces.
Vitamins
These are substances of different chemical compositions, which are vital for the correct functioning of the body. They are needed in very small quantities, but their absence causes different disorders and illnesses. Vitamins are destroyed easily by heat, so they are only found in raw foods.
Vitamins can be classified as follows:
Liposoluble vitamins and hydrosoluble vitamins
Nutritional Needs
We need food to satisfy three types of needs: energetic, structural, and functional and regulatory.
Energetic Needs
To maintain the activity of all our cells, tissues, and organs and do some physical activity, our bodies need energy.
We obtain the energy we need from energy-giving nutrients (sugars and fats), and when these are lacking, also from proteins. This process happens as a result of respiration, which is a combination of chemical (metabolic) reactions that take place in cells.
Different nutrients have different calorific values:
- One gram of fat: 9 kcals
- One gram of sugars: 3.75 kcals
- One gram of protein: 4 kcals
Even when our bodies are resting, they need a minimal amount of energy. This is called the basal metabolic rate and is the energy required to keep our vital functions going: breathing, blood flow, etc.
Calculate:
Men: 66.5 + (13.7 x body mass in kg) + (5 x height in cm) – (6.7 x age in years)
Women: 55 + (9.5 x body mass in kg) + (4.8 x height in cm) – (4.7 x age in years)
Structural Needs
As well as providing energy-giving nutrients, food also provides the body with essential substances to build and repair biological structures.
The most important structural nutrients are proteins, but some lipids also have this function.
Functional and Regulatory Needs
Our bodies need other kinds of nutrients, like vitamins and some minerals, in order to function properly. These ensure that metabolic reactions happen effectively, organs function normally, and all parts of our body work well together. Although our bodies need less of these types of nutrients than the other types, they are still essential.
Food Preservation and Hygiene
The main methods of preserving food are:
Cold, heat, drying, vacuum packing, irradiation, fermentation, smoking, and the use of preservatives.
Additives: are natural or artificial chemical products that are added to food for different purposes, for example: preservatives, colorings, sweeteners, etc.