Continuing with one of the topics covered previously, macronutrients explained in greater detail, in the following post we will discuss lipids or fats, explaining their complexity, composition and characteristics in a simple and understandable way.
Lipids are water-insoluble compounds that are needed to carry out a large number of structural and physiological functions in the body.
Lipids with fatty acids or saponifiable lipids:
Simple lipids:
Fatty acids are compounds generally made up of oxygen, hydrogen and carbon. They are characterized by being insoluble in water.
Depending on the chains they form, we can classify fatty acids into 4 different types:
- Short-chain fatty acids
- Medium-chain fatty acids
- Long-chain fatty acids
- Very-long-chain fatty acids
In addition, we can classify fatty acids into two types: saturated and unsaturated.
Saturated: these are mainly found in foods of animal origin. Structurally, this type of fatty acid does not contain double bonds.
Unsaturated:
- Monounsaturated: they contain a single double bond.
- Polyunsaturated: they alternate a group with a double bond with a group without a double bond.
- Trans: they come from the fat present in meat and milk. Their structure is similar to that of saturated fatty acids.
Essential fatty acids:
These are fatty acids that cannot be synthesized by the body and therefore must be consumed through food or supplementation. They are very important because they are used to carry out a large number of functions.
Among this type of fatty acid, the most relevant is linoleic acid. In addition, linolenic and arachidonic acids are also particularly relevant.
Functions of fatty acids:
Fatty acids are necessary for the regulation of the endocrine and nervous systems. At the metabolic level, fatty acids contain a large amount of energy in the form of ATP, which can be used by the body as fuel in different situations.
– Short- and medium-chain fatty acids can enter cells without difficulty to be used as fuel. However, for this process to be carried out by long-chain fatty acids, a molecule called carnitine must be present. You have probably heard of or consumed an L Carnitine-based supplement during periods of fat loss with the aim of facilitating these processes. This is why it is believed that it may be helpful.
Triglycerides:
This is the name given to fatty acids that esterify glycerol. Their synthesis takes place mainly in the intestinal mucosa, liver and adipose tissue.
Functions:
- They have a protective effect on the different organs and the skeleton (adipose tissue).
- Thermal effect. They protect the body from temperature variations and help maintain body heat.
- Storage of essential fatty acids.
- Storage of fat-soluble vitamins: A,D,E,K.
- Source of energy when necessary.
Complex lipids:
One characteristic of complex lipids is that they have the ability to emulsify fats during digestion.
Complex lipids can be classified into two types: glycerolipids and sphingolipids.
Glycerolipids:
They contain a molecule of glycerin. This classification includes most of the complex lipids present in cells, esterifications by fatty acids and phosphoglycerolipids (regulatory capacity in the body). They perform structural functions, such as maintaining cell membranes.
Sphingolipids:
They do not contain a molecule of glycerin, but contain sphingosine, an amino alcohol. The main food sources from which we can obtain this type of lipid are eggs, organ meats and brains.
Unsaponifiable lipids or lipids without fatty acids:
Sterols
They are present in different cell membranes. The most relevant one is cholesterol.
Cholesterol:
In a future post, we will take a closer look at cholesterol and its characteristics. There are mainly two types of cholesterol:
- HDL: the so-called “good cholesterol.” It acts as a cardiovascular protector.
- LDL: the so-called “bad cholesterol.” It has pathological effects on health.
Bile acids
Bile acids are produced in the liver. Their main function is to act as emulsifiers. In other words, they facilitate the absorption of fats. Subsequently, they are reabsorbed in the small intestine, another proportion in the large intestine, and the remaining product, after undergoing certain alterations, is excreted. Once they have performed their functions, they can return to the liver to be reused.
