Nutrients

Food contains six types of nutrients. Simple nutrients are absorbed through the walls of the digestive tract. Complex nutrients undergo chemical digestion to break down into smaller molecules that are then absorbed through the digestive tract.

Carbohydrates are nutrients found in fruit, vegetables, cereals, pasta, legumes and dairy products, among others.

Carbohydrates are made up of single or double units called sugars. Glucose is the most common sugar and the one most used by the body.

Carbohydrates are generally divided into two categories: simple carbohydrates and complex carbohydrates.

• Simple carbohydrates, also known as sugars, are made up of one or two units. They are characterized by their sweet taste and are the main source of energy used by cells. They are found in fruit, vegetables and dairy products, among other things. Fructose, glucose and lactose are examples of simple carbohydrates.

• Complex carbohydrates are made up of several simple carbohydrates. They do not have a sweet taste. They are found in cereals, pasta and legumes, among others. Starch and cellulose are examples of complex carbohydrates.

Lipids are nutrients that make up the fat in food. They can be of animal or vegetable origin. They are found in meat, vegetable oils, nuts and dairy products, among others.

During digestion, lipids are broken down into glycerol molecules and fatty acids so that they can be absorbed by the body.

Fatty acids can be used by the body to produce energy, while glycerol molecules are used to store energy by forming fat under the skin, in the muscles, and around certain organs. Glycerol molecules are also used to build cell membranes.

Lipids are the body's main energy reserve. They also play a protective role: the fat accumulated under the skin prevents heat loss and the fat covering certain organs, such as the heart and kidneys, helps hold them in place and protect them from shocks.

Proteins are nutrients that are found in many types of animal and plant-based foods.

A protein molecule is a long chain of amino acids. Digestion allows the amino acids to separate and be absorbed by the body.

Once absorbed, amino acids are used by the body to produce new proteins specific to its own needs. Each type of protein is a unique assembly of several amino acids, which gives it a particular shape and function.

The main functions performed by proteins in the body are shown in the following table.

Water is essential to the body's survival. Making up about 60% of the body’s mass, it is the most abundant substance in the human body. Water makes up the majority of the food humans eat, but it is most abundant in juices, fruit and vegetables. 

Water is the solvent for various solutions in the body, such as blood, lymph, sweat, urine and cytoplasm. The main functions of water in the body are described in the following table.

Vitamins are essential molecules used by the body to function properly, even though the quantities required are very small. Daily requirements for each vitamin vary between 0.000006 and 0.001 g. Because these quantities are so small, the microgram (µg) is generally used to express the quantities of vitamins on the nutrition label.

||1\ \text{µg}=0.000001\ \text{g}||

There are 13 different types of vitamins in the human body, including vitamins A, B, C, D, E and K. They are classified according to their properties and functions. The following table shows some of the functions of each type of vitamin.

Minerals are simple chemical elements that make up certain tissues and regulate a number of essential chemical reactions in the body. Although the human body's daily mineral requirements are very low, it is essential to meet them through diet. Fruit, vegetables, meat and nuts, dairy products and fish are all sources of different minerals. The following table shows some of the functions of the main essential minerals.