Nutrients: Essential Substances for Life

Introduction

Humans are heterotrophs, meaning they cannot create their own organic matter. They obtain energy by ingesting substances from other organisms.

Food: Substances from other living things that are ingested.

Nutrients: Simple molecules contained in foods, necessary for life.

Eating: Conscious, voluntary process by which foods are taken from the outside environment.

Nutrition: Complex, unconscious, and mostly involuntary process by which foods are transformed into nutrients.

Carbohydrates (Glucides)

Energy-providing nutrients.

Monosaccharides

Formed only by one molecule.

• Examples: Glucose (cane sugar), fructose (fruit sugar)

Disaccharides

Formed by two molecules.

• Examples: Sucrose (cane sugar), lactose (sugar of milk)

Mono and disaccharides are sweets, soluble in water, and crystalline.

Polysaccharides

Lots of molecules of glucose (even thousands).

• Examples: Starch (almidón), long chain of glucose, glycogen, and cellulose (=long chains of glucose)

Lipids (Fats)

Main Functions

• Produce and store energy
• Structural function: Form the cell membranes
• Regulatory function: Made up of some kinds of vitamins and hormones

Two Types

Saturated

They are solids at room temperature. Most of them have animal origin.

• Examples: Butter, coconut, palm oils, cold meat, milk, and eggs

Unsaturated

Liquids at room temperature. Mostly vegetal origin. Name as oils.

• Examples: Olive oils, nuts, seeds, and fishes

Proteins

They are formed by chains of molecules called amino acids.

Functions

• Structural function: Made up the muscles, the collagen, nails, hair...
• Transport substances: Examples: Hemoglobin...
• Defensive: Form the antibodies
• Regulatory: Form hormones, enzymes...

Food rich in proteins: meat, fish, milk, egg, and legumes... Are only 20 amino acids, and 9 are essential because we cannot make them up in our body.

Water (Inorganic)

Essential for life, mostly component of living matter.

Functions

• It is the medium where the biological processes happen (chemical reaction)
• Dissolves many substances (Universal solvent)
• Maintain the body temperature, and its the basic component of the organic fluids (blood, urine...).

Mineral Salts (Inorganic Nutrients)

The are found in foods we usually eat. The most important are: calcium, sodium, phosphorus, iron, iodine, potassium...

Functions

• Structural: Make up structures like bones and teeth
• Regulatory: Regulate vital processes, for example:

• Na, K: Necessary to transmit the nerve impulse
• Ca: To muscular contraction
• Fe: Form the hemoglobin