Fats or lipids in the diet

Undoubtedly, fats or lipids give food aromas, textures and flavors tempting for everyone; this makes some people abuse their consumption, incorporating to the body large amounts of calories that if they are not used in physical activities, will be stored as fat, increasing the risk of being overweight and obesity, disorders that are closely related to many chronic diseases.

On the other hand, some individuals mistakenly consider that lipids only contribute calories to the diet; and obsessed with weight and figure, reduce their consumption below the established minimum limits; putting their health at risk, since lipids, besides being a concentrated source of energy and constitute a protective element of the organism, perform other functions such as transporting vitamins A, D, E and K.

In this presentation you will learn about the components of lipids, the role they play in the diet and the foods that contain them in greater proportions.

What are fats or lipids?

Fats or lipids are a set of organic molecules, made up of carbon, hydrogen and oxygen that can also contain phosphorus, sulfur and nitrogen. They are not soluble in water and are found in animal tissues (known as fats), as well as in the seeds and fruits of certain plants (mostly known as oils).

Are "lipids", "fats" and "oils" the same thing?

We would first like to clarify that the terms "fats" and "lipids" are used synonymously to designate all fatty substances (not soluble in water, solid or liquid), which can be found mainly in the adipose tissues of animals, as well as in the seeds or fruits of certain plants. For example lard, butter, margarine; and olive, sunflower, soybean, etc. oils.

However, the term "fats" is often used to designate only those fats that are solid at room temperature, e.g. lard, butter, coconut fat, palm fat and margarine. And the term "oils" to designate only fats that are liquid at room temperature, such as olive oil, and sunflower, corn, soybean, peanut and fish oils.

Thus, the term "lipids" always includes all fatty substances, whether solid or liquid.

Key components of lipids or fats

Lipids or fats include:

• Triglycerides.

• Phospholipids.

• Sterols.

Triglycerides

Triglycerides are the main component of body fat in humans, other animals and vegetable fat. They are made up of one molecule of glycerol and three molecules of fatty acids. The differences between fats depend mainly on the fatty acid composition of each one.

There are three fundamental types of fatty acids:

• Saturated fatty acids (SFA): They are those that in their chemical structure have only single bonds between carbon atoms; this gives them great stability and the characteristic of being solid at room temperature. Saturated fatty acids predominate in foods of animal origin, such as fatty meats, sausages, butter and whole cheeses, etc. They are also found in large quantities in coconut and palm oils, which are widely used in industrial pastries and baked goods.

  Studies show that saturated fats, when consumed in higher than recommended amounts, are the dietary factor that most increases the levels of bad cholesterol in the blood, thus increasing the risk of coronary heart disease.

• Monounsaturated fatty acids (MFA): They are those that in their chemical structure have only one double carbon bond. This structure causes them to be in a liquid state at room temperature. These acids are called oils and are manufactured only by plants.

  Monounsaturated fatty acids are found in olive oil and nuts. Moderate consumption of monounsaturated fatty acids helps lower bad cholesterol (LDL) levels in the blood and increase good cholesterol (HDL). They also protect against oxidation and lower blood pressure.

• Polyunsaturated fatty acids (PUFA): These are those that have two or more double carbon bonds in their chemical structure. Their structure causes them to be in a liquid state at room temperature. Within this group are the oils known as omega-3 and omega-6.

  The omega-3 polyunsaturated fatty acids are found in the tissues of certain oily blue fish such as salmon, sardines, anchovies, tuna, mackerel, etcetera. It is also contained in some vegetable sources such as walnuts, flaxseed, canola and soybean oils. Moderate consumption of omega-3 fatty acids reduces blood pressure, prevents arrhythmias and avoids the formation of blood thrombi.

  Omega-6 polyunsaturated fatty acids are found in most vegetable oils (sunflower, corn, soybean, etc.); walnuts and avocado.

Phospholipids

Phospholipids are compounds that follow triglycerides in nutritional importance. They are a type of phosphorus-containing lipids and their most important function is to form the membranes of our cells and act as biological detergents. It has been shown to be present in venous blood, human brain tissue and bile.

It is found in sufficient quantities in eggs, milk, fish, soybeans, sunflower and rapeseed.

Sterols

Sterols are the next most nutritionally important lipid component to phospholipids. One of the most important sterols is cholesterol, as it is the precursor in the synthesis of substances such as vitamin D and sex hormones; it is also involved in numerous metabolic processes and is an important component of cell membranes.

Cholesterol can be obtained only in foods of animal origin. Cholesterol is rich in liver, offal, egg yolk, cream, butter, highly processed cheeses and fatty meats.

Cholesterol is essential for life, however, when its levels in the blood are too high or too low, they can be harmful to health. In the next presentation, we will go into more detail on this subject.

What are hydrogenated fats or "trans" fatty acids?

They are artificial fats that are obtained through industrial processes where unsaturated oils become saturated and therefore solidified. They are manufactured to obtain fats that are easier to handle and have a longer shelf life.

Some margarines and partially hydrogenated oils may contain hydrogenated fats. These fats are used in the manufacture of puff pastry dough, pastries, cookies, industrial bakery products, potato chips, snacks and popcorn.

The very frequent consumption of trans fatty acids is associated with an increased risk of myocardial infarction, atherosclerosis and diabetes.