Macronutrients (III)

Lipids are a group 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, as well as in the seeds and fruits of certain plants.

Fundamental components of lipids or fats

Lipids or fats include:

• Triglycerides.

• Phospholipids.

• Sterols.

Triglycerides

They are formed by a molecule of Glycerol and three molecules of fatty acids. The differences in quality between lipids depend fundamentally on the fatty acid composition of each one. There are three main types of fatty acids: saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids.

Saturated fatty acids (SCFA)

They are solid at room temperature. They are solid at room temperature and predominate in foods of animal origin: lard, butter, meats and fatty dairy products. They are also contained in coconut and palm oils.

Monounsaturated fatty acids (MUFA)

They are liquid at room temperature. They are liquid at room temperature and are manufactured only by plants. MFAs predominate in olive oil and nuts.

Polyunsaturated fatty acids (PUFA)

These are liquids at room temperature and are manufactured by plants and some types of fish. Within this group are oils of the omega-3 and omega-6 series.

Omega-3 polyunsaturated fatty acids are found in the tissues of certain fatty fish and in some vegetable sources such as nuts.

Omega-6 polyunsaturated fatty acids are found in most vegetable oils, nuts and avocado.

Phospholipids

Phospholipids are a type of phosphorus-containing lipid whose most important function is to form cell membranes and act as biological detergents. Phospholipids are found in eggs, milk, fish, soybeans, sunflower and rapeseed.

Sterols

Among the sterols, cholesterol stands out, since it is the precursor in the synthesis of vitamin D and sex hormones; it is also involved in metabolic processes and is an important component of cell membranes. Cholesterol is contained in organ meats, egg yolks, cream, butter and fatty meats.

What are hydrogenated fats or "trans fats"?

They are artificial fats obtained through industrial processes where unsaturated oils become saturated and therefore solidified. Some margarines and partially hydrogenated oils may contain hydrogenated fats.

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

Why should we include lipids in our diet?

• They participate in the formation and maintenance of various structural components of the organism. For example: cholesterol, phospholipids and glycolipids form the lipid bilayers of cell membranes.

• They constitute a concentrated source of energy.

• They protect and coat different parts of the body. For example: fats protect the hair and skin.

• They intervene as regulators in some cellular processes. For example: In the synthesis of steroid hormones and bile salts.

• They provide certain essential acids. For example: linoleic acid and alpha-linolenic acid.

• They transport and participate in the absorption of fat-soluble vitamins (A, D, E, and K).

• They are involved in the regulation of the blood concentration of lipids and lipoproteins.

Important: Restrictions of lipids or fats in the diet of children can bring serious disorders for their physical and intellectual development and their general health.

What are the healthiest fats and why?

The healthiest fats are monounsaturated and polyunsaturated fats:

• Moderate consumption of monounsaturated fats help lower blood levels of "bad cholesterol" (LDL) and increase "good cholesterol" (HDL). They also protect against oxidation and lower blood pressure. Monounsaturated fats are found in olive oil and nuts.

• Moderate consumption of polyunsaturated fats of the omega-3 and omega-6 types reduce blood pressure, prevent arrhythmias and prevent the formation of blood thrombi.

• Omega-3 polyunsaturated fatty acids are found in the tissues of oily fish such as salmon, sardines, anchovies, tuna, mackerel, etcetera. It is also contained in walnuts, flaxseed, olive, canola and soybean oils.

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

Less healthy fats

Saturated fats are considered less healthy because when consumed in quantities higher than recommended, they increase the "bad cholesterol in blood" indexes, increase the risk of developing heart and cerebrovascular diseases; in addition, they favor the increase of body weight and obesity, disorders that contribute to the appearance of other chronic diseases.

The following foods are rich in saturated fats: lard, butter, fatty meats, sausages, fatty dairy products, coconut and palm oils, and so on.

Harmful fats

Hydrogenated fats or trans fats are considered harmful for the following reasons:

• They reduce the levels of "good cholesterol" in the blood and increase "bad cholesterol", accelerating the development of atherosclerosis.

• They increase the risk of type 2 diabetes mellitus.

• They increase the risk of myocardial infarction.

These fats are sometimes used in the preparation of puff pastry, cakes, cookies, industrial bakery, etc.

How much fat should be consumed daily?

In preschoolers from 2-3 years of age it is recommended that fat should represent between 30 and 35% of the total energy provided by the diet, and from 4 years of age onwards between 25 and 35%.

It is recommended that the total lipid intake be obtained from the different types of fats in the following proportions:

• That 15% should come from monounsaturated fatty acids, contained in olive oil and nuts.

• That 10% comes from polyunsaturated fatty acids, preferably omega-3, contained in blue fish, soybean, walnut or rapeseed oils.

• The remaining 10% should come from saturated fatty acids, preferably from whole milk, fish, eggs and lean meats.

• Less than 300 mg of cholesterol per day should be consumed.

• Avoid consumption of trans fats.