Types of fats (good and bad) and their functions

Lipids are organic biomolecules generally composed of carbon and hydrogen and, to a lesser extent, also oxygen. However, sometimes they can contain phosphorus, nitrogen and sulfur.

The world of lipids can be confusing terrain, as the terms lipids, fats, fatty acids, or triglycerides can be used interchangeably although they do not mean the same thing. In this article, we will focus on fats and their nutritional importance, so we will not go into detail about other important functions of lipids, such as: structural or transport function.

Simple and complex lipids

The group of lipids includes many organic compounds that basically share two essential characteristics: they are insoluble in water and soluble in organic solvents. Traditionally sand generally distinguish between simple lipids (esters of fatty acids with alcohols) and complex lipids.

The most important simple lipids are triglycerides, which are often referred to as fats because they are stored in adipose tissue and are the main constituents of vegetable oils and animal fats, and their function is primarily energetic, but also insulating. Triglycerides are largely composed of fatty acids, for example palmic acid. Complex lipids, on the other hand, generally fulfill structural and functional missions.

The fact that the properties of all these substances are different makes their metabolism very different as well.

    Functions of lipids

    In general, the functions of lipids are:

    • energy: For each gram of fat provide 9 kcal. If the fat intake exceeds the daily requirement, it is stored directly in fatty tissue as triglycerides.
    • Of construction: Certain lipids such as cholesterol are part of cell membranes and are precursors of hormonal steroids, bile acids and vitamin D.
    • transport: They carry fat soluble vitamins (A, D, E, K and carotenoids).
    • They increase appetite: They enrich the taste of food

    In addition, lipids provide essential fatty acids to the body

    Essential and non-essential fatty acids

    Fatty acids, like amino acids, can be divided into essential and non-essential fatty acids. The difference between these is that we have to eat the essential elements of the diet and the non-essential elements can be produced by the body. Although the essentials are classified into families such as omega 3 fatty acids, the best known are, for example, linoleic acid or alpha-linolenic acid.

    • You can read more about essential amino acids in our article: “The 20 Types of Proteins and Their Functions in the Body”

    Saturated, unsaturated or trans fats (or fatty acids)

    Fatty acids, depending on their chemical structure, can also be classified in different ways:

    saturated fats

    All foods that contain fat are made up of different types of fat, but the amounts of each type usually differ depending on the food. For example, pork is high in saturated fat, while almonds are high in unsaturated fat (also called healthy fats).

    The fatty acids in these fats they do not have double bonds in their chain and are generally solid at room temperature. The body cannot take full advantage of this type of fat, so it ends up accumulating in the arteries which can lead to serious health problems. This is why different organizations specializing in this subject warn that the consumption of this type of fat should be moderate.

    Saturated fat increases cholesterol more than any other type of fat (except trans fat, which we will see later), so excessive consumption can increase cholesterol biosynthesis and has a thrombogenic effect. It is found in foods of animal origin such as meat, sausages, milk and its derivatives (cheese, ice cream).

    unsaturated fats

    Unsaturated fats they are known as healthy fats because they increase good cholesterolThey stabilize the heart rate, relieve inflammation and also provide other beneficial functions for our body. This type of fat is mainly found in plant foods and fish.

    It is possible to distinguish two types:

    • monounsaturated fat: This type of fat is found for example in olive oil, and the most famous monounsaturated fatty acid is oleic acid. They are generally liquid at room temperature and have a single double bond in their structure.
    • polyunsaturated: They are found in foods of plant origin, fish and seafood. They have two or more double bonds in their structure and are essential. They are classified into groups such as omega-6 (linoleic and arachidonic acid) or omega-3 (linolenic acid, eicosapentaenoic acid or docosahexaenoic acid).

    trans fats

    While saturated fat is harmful to the body in the long run, trans fats (processed fats) found in hydrogenated oils and some processed foods are even worse. Technological processes, such as hydrogenation, petroleum refining, etc., causes chemical transformation in some fatty acids, which makes it harmful to our body.

    Health professionals have long warned that diets high in trans fats increase beta-amyloid in the brain, which is associated with Alzheimer’s disease. In addition, the journal Neurology published research which found that this type of fat is associated with brain contraction and an increased risk of stroke.

      Other fat classifications:

      In addition to the above, fats can be classified differently:

      According to its origin

      Fats can also be classified according to the source from which they are obtained and can be of plant or animal origin. Examples of animal fats are those found in eggs or beef; while those of plant origin are, for example, those found in nuts or olives.

      According to its shape

      Depending on their form, they can be solid or liquid. Liquids are known as oils and solids simply as fats. This difference can be seen with the naked eye, although it is true that the consistency of fats can vary and have a gelatinous texture reminiscent of liquids.

      This classification of fats can be done with the naked eye.

      According to its visibility

      Finally, fat can be classified as visible or invisible. Visible fat is, for example, that found in a piece of loin, so it is possible to remove it and not consume it. In contrast, invisible fat is, for example, that found in milk.

      Bibliographical references:

      • Coleman, RA, Lee, DP (2004). Triacylglycerol synthetic enzymes and their regulation. Progress in lipid research. 43 (2): 134-176.
      • Eyster, KM (2007). Membrane and lipids as full participants in signal transduction: transduction of lipid signals for the non-lipid biochemist. Progress in physiological education. 31 (1): pages 5 to 16.
      • Parodi, AJ, Leloir, LF (1979). The role of lipid intermediates in the glycosylation of proteins in eukaryotic cells. Biochimica and Biophysica Acta. 559 (1): 1-37.
      • Mashaghi, S., Jadidi, T., Koenderink. G., Mashaghi, A. (2013). Lipid nanotechnology. International Journal of Molecular Sciences. 14 (2): 4242-482.
      • Mozaffarian, D .; Katan, MB; Ascherio, A .; Stampfer, MJ; Willett, WC (2006). Trans fatty acids and cardiovascular disease. New England Journal of Medicine. 354 (15): pages 1601 to 1613.
      • Yam D, Friedman J, Bott-Kanner G, Genin I, Shinitzky M and Klainman E. (2002). Omega-3 fatty acids reduce hyperlipidemia, hyperinsulinemia and hypertension in cardiovascular patients. Journal of Clinical and Basic Cardiology 5 (3): 229-231.

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