What is lipids?
Lipids are one of the three macro nutrients (= nutrient that provides energy ) essential for the proper functioning of our body, alongside carbohydrates and proteins .
In everyday language, we often tend to speak of “fat” and it is not for nothing since “lipid” comes from the Greek “Lipos” which means “fat”. Lipids are therefore fats – essential for our body (e.g our brain is made up of at least 50% lipids). They have a very negative image linked to the role they perform in the appearance of pathology such as cardiovascular disease, obesity, cerebrovascular diseases, etc.
The fundamental roles of lipids
# 1 An important source of energy for our organization
Lipids play a very important role in our body because they provide energy to our body. One gram of fat provides 9 kilo calories , more than double what protein and carbohydrates provide.
Another difference with proteins and carbohydrates: lipids are stored in our body in considerable quantities (in the form of ” triglycerides”) . These reserves can provide energy to our body during a long-term effort, during an extended fast or between two meals.
# 2 A significant intake of essential fatty acids
# 3 Transport of fat soluble vitamins
But the role of lipids does not stop there: they are essential for our body because they allow the transport of fat soluble vitamins (A, D, E and K). Without this, our body could not be supplied with fat-soluble vitamins, which would expose us to serious deficiencies …
# 4 A significant structural role
Lipids are one of the components of the structure of our body’s cells: they form the membranes of our cells.
# 5. … and hormonal
Lipids also participate in the synthesis of certain substances such as hormones .
From a biochemical point of view, there are 3 types of fatty acids :
- Saturated fatty acids: although they can bring energy to our body, they should nevertheless be consumed in moderation (no more than 25% of daily lipid intake ). Indeed, also called “bad fats”, they increase the bad cholesterol as well as the risk of coronary mortality.
- Monounsaturated fatty acids: unlike saturated fatty acids, they have a beneficial effect on cholesterol . They also reduce the risk of cardiovascular disease and hypertension, they should represent 65% of daily fat intake . The main form of monounsaturated fatty acid is oleic acid (omega 9).
- The polyunsaturated fatty acids that can be made by the body from two precursor fatty acids. These precursor fatty acids are called essential fatty acids (or essential) because the body does not know how to make them, so we must bring them by food.
- There may also be mentioned trans fatty acids, which are chemically transformed acids in the laboratory, created by the agri-food industry. They increase the lipid per oxidation (= formation of free radicals responsible for premature aging and cellular damage in the body) and promote the deposition of lipids on the internal walls of the vessels .Essential fatty acids It is also possible to classify fatty acids from a physiological point of view . Thus, we can distinguish:
- the essential fatty acids necessary for the development and the good functioning of the human body, but which our body does not know how to manufacture ;
- conditionally indispensable fatty acids , essential for the normal growth and physiological functions of the cells but which can be made from their precursor if it is provided by the diet.
- Non-essential fatty acids (“non-essential”) that our body knows how to synthesize.
All the essential and conditionally indispensable fatty acids constitute the essential fatty acids . There are two main families of essential fatty acids:
- omega 6 polyunsaturated fatty acids , the essential precursor of which is Linoleic acid .
- omega 3 polyunsaturated fatty acids , the essential precursor of which is alpha-linolenic acid .
Among the lipids, there are also steroid which are distinguished from cholesterol (of animal origin) and steroid (of plant origin):
– Cholesterol can have two sources. The one from food represents only a tiny part of our contributions , the majority of our contributions being produced by our liver . It is precisely an excessive or insufficient production of cholesterol by our liver that makes it harmful (risks of increased cardiovascular accidents).
– and phytosterol , of plant origin: has positive benefits on our health, since it limits the absorption of cholesterol of animal origin . It therefore has an important role in the prevention of pathology such as cardiovascular diseases.
Recommended nutritional intake in lipids
In a suitable diet , lipids should represent 35 to 40 % of the (total energy intake) every day. It would be particularly important in infants (children from 0 to 2 years), where it would be essential for the development of the central nervous system and psycho motor development . Lipid intake should also not be neglected in pregnant and lactating women , for the sake of the baby’s development.