Understanding Dietary Fats
It is important to talk about dietary fats as their intake impacts cholesterol levels. Fats are one of the nutrients that provide energy to our body and consumed through foods. The fat we consume comes from two sources:
1- Visible fat used for cooking or seasoning some foods (salads, vegetables, bread) like olive oil, or one that is around meat or chicken skin, which can be added and removed.
2- Invisible fat that is contained “naturally” in foods (meats, nuts, dairy products) or added during processing (prepared foods, appetizers or snacks, pastries).
Different types of dietary fat
Chemically speaking, fats are organic compounds composed of carbon, hydrogen, and oxygen. Their main function is to provide energy – 9 calories per gram of fat consumed, twice the calories provided by carbohydrates and proteins (each of these nutrients provide 4 calories per gram). Fats are composed of triglyceride molecules in turn formed by fatty acids. Fatty acids are classified based on the presence of double bonds in their molecule, resulting in different types of fat:
Unsaturated fats (double bonds) – the “Good”
These are found in plant foods such as vegetable oils (olive, corn or sunflower oil). Also in nuts (walnuts, almonds, peanuts…) and seeds (sesame, sunflower, flaxseed). Coconut oil or palm oil, although plant oils contain saturated fatty acids, rather than unsaturated fatty acids.
These fats are liquid at room temperature. Depending on the number of double bonds present, they are classified as:
• Monounsaturated (one double bond)
The most representative are the oleic acid found mainly in olive oil and other vegetable fats and seed oils (sunflower oil, rapeseed oil). They are also found in walnuts, almonds, and avocados. Replacing saturated fats with unsaturated fats in the diet helps maintain normal blood cholesterol levels.
• Polyunsaturated (two or more double bonds)
Polyunsaturated fats are essential for our body because it can not synthesize them, and must be supplied through the diet to regulate metabolic processes of the cardiovascular, immune and pulmonary systems, among others. They are present in foods of plant and animal origin. There are two families within these:
– Omega 3: within this group are linolenic acid, eicosapentaenoic acid (EPA) and the very present docosahexaenoic acid (DHA) in fatty fish. Omega 3 fatty acids are found in soybean oil, rapeseed oil, nuts (walnuts), fatty fish like salmon, herring, tuna, mackerel, anchovies, sardines, etc. Linolenic acid intake helps maintain your cholesterol at healthy levels. The beneficial effect is obtained with a daily intake of 3 g of this fatty acid.
– Omega 6: within this group is the linoleic acid present in the soybean oil, corn oil, sunflower oil and nuts (walnuts, etc.). The beneficial effect on your cholesterol is obtained with a daily intake of 10 grams of linoleic acid.
Saturated fats (no double bonds) – the “Gray”
These are usually the most present in our diet as they are found in animal foods such as meat, sausages, milk and dairy products (cheese, ice cream). These are fats that solidify at room temperature. They can also be found in vegetable oils such as coconut oil or palm oil (used in industrial bakery, salty snacks, and processed products). The high consumption of saturated fat can promote increased levels of LDL cholesterol commonly known as the “bad” cholesterol. However, scientific studies have not been able to prove that saturated fats increase heart disease risk. Nevertheless, it has been established that replacing them with unsaturated fats decrease heart disease risk. In short, you do not have to avoid saturated fats. You are recommended to limit them.
Trans fats – the “Bad”
These fats are produced through a chemical process called hydrogenation. This procedure is employed to enhance flavor and change the texture of foodstuffs, prolonging their shelf life at low cost. However, hydrogenation causes a portion of polyunsaturated fats to transform into saturated fats, becoming solid fats. They are found in fried foods, snacks, baked goods (cakes, muffins, scones, biscuits, cookies), some dairy products and processed foods.”Partly hydrogenated oil” is also the term used to list trans fats on food labels, so don’t get tricked when it is written “Trans Fat 0g”.
Consumption of trans fatty acids causes a more negative effect than saturated fat in the body because it really increases levels of LDL cholesterol, triglycerides and also reduces HDL cholesterol (good cholesterol) levels, highly increasing the risk of coronary heart disease. On contrary to saturated fats, the link between trans fats and heart disease has been scientifically established, and researchers alert that they are harmful even in the small intake. If just 2% of your day-to-day calories come from trans fats, your heart diseases risk increase up to 25%. And that is not all, you are also subjected to strokes, insulin resistance, diabetes, hypertension and other chronic diseases.