Fats (also known as lipids) are complex organic compounds that are generally synthesized by plant cells.
In the diet, lipids are mostly found in the form of visible fats (lard, butter, margarine, oil, and others) or in the form of invisible fats which are an integral part of the plant and animal tissue, such as: meat, egg yolk, sunflowers, corn, walnuts and peanuts. Animal secretions (e.g. milk and cheese) are also considered as invisible fats, as well as ingredients that are used to prepare food, such as pasta, sauces, dressings, mayonnaise, meat products and others.
Lipids are composed of fatty acids, and they are of particular importance for human consumption. That’s why we will mostly discuss about them from now on.
Fatty acids according to the chemical structure, are divided into:
Saturated fatty acids may have a different number of carbon atoms, but saturated fatty acids most commonly used in the human nutrition have 8-18 carbon atoms (palmitic and stearic). Palmitic and stearic acids usually originate from animal foods (meat).
Unsaturated fatty acids are divided into:
In terms of chemical structure, the only difference between monounsaturated and polyunsaturated fatty acid is that monounsaturated fatty acids have just one double bond in their chain and polyunsaturated have two or more double bonds in their chain. Saturated fatty acids do not have any double bonds in their chain.
It is important to know that polyunsaturated fatty acids are essential, which means that they must enter the body through food because the body cannot create them on its own. Therefore, these fatty acids are considered "good" and are recommended for regular daily intake, but of course in limited quantities.
A special form of polyunsaturated fatty acids, which are referred to as n-3 polyunsaturated fatty acids are present in fish in large amounts and these fatty acids have a high nutritional value and are beneficial to the organism. They originate from the fish that feeds on plankton. Therefore, these n-3 fatty acids are significantly more consisted in salt water fish. Fish oil has a high biological and nutritional value because of the extraordinary content of essential and protective fatty acids, vitamin A and vitamin D which is why it is recommended for all ages.
Cold pressed oils also have high biological value and are recommended for all ages. Olive oil is very appreciated because it contains a high level of oleic acid, which belongs to the group of monounsaturated fatty acids. Other oils like corn and sesame oil are also recommended. Grape seed oil is recommended for high heat deep frying, while for salads it is best to use olive oil.
Children, teenagers, and adolescents can use food with both animal and vegetable fats, while the elderly should use mainly food with vegetable fats.
Butter and margarine should be avoided because they contain mostly saturated fatty acids and a really large number of calories.
Digestion of fats begins in the mouth, and it ends in the small intestine under the influence of an enzyme called intestinal lipases. The absorption and utilization of fat in the body is almost always complete. When fats enter your body through food, they are used for the synthesis of numerous molecules that your body needs. However, if you are eating more lipids than you need, the excess fats will be stored in adipocytes (fat cells) in fat tissue.
An interesting fact is that adipocytes (fat cells) can store unlimited amounts of fat. These fats can be used as main energy source in the case you lack carbs. You should know that carbohydrates are the primary source of energy and that your body uses fats only when you spend carbohydrates obtained from food. So, bear in mind that if you want to lose fat it is also important to reduce your intake of carbohydrates.
Fats are an important part of human nutrition and must be taken every day in moderate amounts because they are essential to our body to build new molecules but also to provide energy. The excess fats are deposited in fat cells, and they can store unlimited amounts of fat. It is necessary to limit fat intake to 20-30 % of total daily food intake, while saturated fatty acids should be limited to not more than 10 % of the total food intake.