Food

Protein

Protein is made up of amino acids. Specifically, eight of these are eight called essential amino acids. They cannot be synthesised by the body and must be supplied daily in the diet.

Therefore, a balanced diet should have:

• 50% animal protein or of high biological value (so called because it contains all the essential amino acids).
• 50% vegetable protein: legumes, cereals and dried fruit. To increase the biological value of these proteins, cereals and legumes can be combined in the same meals, as their amino acids are complementary.

Carbohydrates

Their main function is as a source of energy, they are the principal source of fuel for cells in the body. They are subdivided into:

• Simple carbohydrates: which are digested and absorbed rapidly, quickly raising blood glucose (blood sugar). Simple sugars are found in pastries, desserts, sugar, sugary drinks, juices, dried fruit and derivatives.
• Complex carbohydrates: require more time to be digested, so their absorption and passage into the blood occurs more slowly and gradually. Complex carbohydrates are found in legumes, tubers, bread, rice, pasta, cereals and vegetables and to a lesser extent in vegetables.

Eating complex carbohydrates every day  is recommended, limiting simple sugars to less than 10%.

Dietary Fibre

This is a heterogeneous group of substances, some soluble and others insoluble, the majority are carbohydrates. Fibre is not assimilated by the body.

Its main functions in the body are:

• To produce the sensation of satiety.
• To reduce the absorption of cholesterol and slow the absorption of glucose.
• To stimulate and regulate bowel function.
• To reduce the absorption of toxic substances.

Foods highest in fibre are legumes, cereals and whole grains, unpeeled fruits and vegetables.

Fats and Lipids

These are essential nutrients because they provide energy, essential fatty acids (that the body cannot synthesise) and liposoluble vitamins. Fats found in foods consist mainly of triglycerides and, to a lesser extent, of other complex fats such as cholesterol, phospholipids, etc.

Triglycerides are composed of fatty acids:

• Saturated fatty acids are found in animal fats and coconut and palm fats, used frequently by the baking industry. They raise levels of LDL-cholesterol levels (the “bad” one for good health) in the blood, and in excess they are harmful to the body.
• Monounsaturated fatty acids, found in olive oil, raise HDL cholesterol, the “good” one for good health.
• Polyunsaturated fatty acids are found in oily fish or fats from marine animals (omega 3) and seed oils such as sunflower, corn and soy (omega 6).
• Trans fatty acids, found in margarine and the hydrogenated fats used in the fabrication of pastries and desserts as well as potato crisps. They raise levels of LDL-cholesterol and triglycerides, and lower the HDL-cholesterol, the “good” cholesterol

Cholesterol is found in animal fats: egg yolk, milk, organ meats, seafood, etc. Its consumption increases the total blood content of cholesterol and LDL-cholesterol (“bad”) and should therefore be limited.

Phospholipids are key elements in the formation of cell membranes.

Vitamins

Vitamins have important regulatory functions in many processes in the body, but must be consumed in small quantities.

• Water-soluble vitamins are found in vegetable foods, with the exception of B12, which is only found in food of animal origin.
• Fatty foods are often good sources of fat soluble vitamins.

A varied and balanced diet usually covers dietary intake requirements throughout the different stages of life.

Minerals

These can be classified according to the needs of the body:

• Macrominerals: calcium, phosphorus, magnesium, sodium, potassium, chloride and sulphur. Recommended intake for each is greater than 100 mg/day.
• Trace Minerals: iron, zinc, iodine, etc. Recommended intake is less than 100 mg/day.

They play a part in the regulation of different metabolic functions: regulation of water balance, nerve function, maintenance of osmotic pressure, and enzyme constituents.

Some minerals also play an important role in the formation and maintenance of teeth and bones.

Vegetables and dried fruit are good sources of minerals, which should be supplied by a balanced diet.