See also: good cholesterol and bad cholesterol
Introduction
Fats and / or lipids: functions
Lipids, commonly (and from a chemical point of view improperly) also defined as fats, are macromolecules useful for the human organism; they represent a more heterogeneous group than proteins and carbohydrates, therefore, their classification and related functional analysis are at least complex .
Basics of classification of fats
According to the Lehlinger classification, fats can be classified into simple and complex on the basis of the assumption that they constitute one or more molecules:
- Simple or NOT saponifiable: aliphatic alcohols, sterols (mainly cholesterol and phytosterols), tocopherols (vit E), terpenic alcohols, triterpene dialcohols, hydrocarbons (toxic).
- Complex or saponifiable: tri-, di-, mono-acylglycerols; phospholipids, fatty acids, sterol esters; waxes are composed of 2 fatty acids + ethylene glycol ... not like fats which are composed of glycerin + 3 fatty acids.
Functions of fats: sometimes good and sometimes bad
Trying to make the article less scientific and more "palatable", below we will analyze individually (but without going into details) all types of dietary fats / lipids; in particular, we will try to describe their "functional impact on" the organism. distinguishing good from bad fats.
Simple fats: are they good or bad?
Aliphatic alcohols, terpene alcohols and triterpene dialcohols
They are organic compounds (similar to fatty acids) naturally present in foods which, by determining the basic structure of essential oils, give the typical "aroma" to foods (eg: menthol, citronellol ...). They are MINOR lipid compounds to consider on average GOOD FATS.
NB. The most known alcohols in nutrition are METHANOL and ETHANOL, two molecules naturally LOW present (or present only in trace amounts) in food. The first is a TOXIC fuel for the organism (therefore a BAD molecule), while the second is a less toxic product (even if dose-dependent) present in fermented and distilled drinks.
Sterols:
They are chemical compounds deriving from sterol (chemically defined as a polycyclic compound formed by four rings). They differ in zoosterols (present in animal organisms: cholesterol, steroid hormones and vitamin D) e phytosterols (present in plant organisms: the best known are campesterol, sitosterol and stigmasterol).
- Food zoosterols are naturally present in foods of animal origin; the most important are the cholesterol (considered a BAD FAT because its excess in the blood is responsible for the "increase in mortality from cardiovascular diseases) and the various forms of vitamin D or calciferol (considered a GOOD FAT as it acts as an ESSENTIAL vitamin or provitamin for bone calcification and the prevention of osteoporosis).
- Food phytosterols (and similarly stanols and policosanols) are contained above all in some seasoning oils, legumes, vegetables and fruit; they represent a range of molecules with different functions, including: antioxidant, antitumor, hypocholesterolemic, estrogen-like; it would be essential to dedicate a "whole chapter to their functions but, what is certain, is that they are considered absolutely GOOD FAT.
Tocopherols:
Also known by the name of vit. E. They are a group of ESSENTIAL molecules (contained in vegetable oils and vegetables) as they perform the antioxidant and antithrombotic fluidifying functions of the blood. They are absolutely to be included among the GOOD FATS.
Hydrocarbons:
They are organic compounds without the functional group. They include two categories of molecules (aliphatic and aromatic), different both from the chemical and physical-structural point of view; in this regard, it is however essential to remember that: "in violent cooking at very high temperatures, the carbonization of some macronutrients gives rise to the formation of polynuclear aromatic hydrocarbons, also called polycyclic aromatics (such as the "ANTHRACENE), and all" acrolein. These, in addition to being polluting agents, have a highly toxic, irritating and CARCINOGENIC effect ".
Polycyclic aromatic hydrocarbons and acrolein are volatile lipid derivatives considered ABSOLUTELY BAD FATS (to be avoided or consumed in the minimum quantity possible).
Complex fats: are they good or bad?
Fatty acids and tri-, di-, mono-acylglycerols (glycerol esters or triglycerides):
They are lipids useful for energy supply; fatty acids provide 9kcal / g and should represent between 25 and 30% of the calories in the diet. There is an essential difference in the quality of fatty acids, which in the first analysis can be differentiated into SATURED and Unsaturated;
- SATURATES (mainly deriving from animal-type foods) are commonly defined as BAD FATS because, while providing the same calories as the others, they tend to raise circulating LDL cholesterol, favoring the onset of cardiovascular diseases.
- The UNSATURED (mainly deriving from vegetable type foods), on the contrary, are very useful in the preservation and cooking of foods (monounsaturated, mainly contained in "extra virgin olive oil"), and also include a category of molecules, some of which are essential ( polyunsaturated, mainly contained in seasoning oils, dried fruit, blue fish and fish oil). These essential fatty acids (AGE or PUFA) belong to the omega3 family (contained above all in blue fish, in the oil of fish, krill oil and some vegetable oils) and omega6 (contained above all in vegetable oils and dried fruit), and have very important functions for the organism.
- Ultimately, monounsaturated fatty acids can be considered GOOD FATs provided they are provided in an appropriate measure, quantities beyond which, like SATURATED and NON-essential polyunsaturated fatty acids, they contribute to the "increase in body weight due to adipose deposits; while ESSENTIAL polyunsaturated fatty acids, if introduced in the right reciprocal ratio (omega3: omega6 = 1: 3 or more in favor of omega3), they are considered absolutely GOOD FATS.
NB. There is a category of INDUSTRIALLY MANIPULATED lipids defined HYDROGENATED FATS; these, although originally unsaturated, are industrially subjected to hydrogenation to acquire the physical properties of SATURES. From a metabolic point of view they behave exactly like saturated fatty acids BUT sometimes they contain a significant amount of TRANS fatty acids, UNWANTED molecules (naturally present only in trace amounts in food). Hydrogenated fats, and especially trans molecules, like saturates or worse, are considered ABSOLUTELY BAD FATS (to be avoided or consumed in the minimum possible quantity).
Phospholipids:
They are esters of glycerol associated with fatty acids and a phosphate group; they are mainly contained in offal (brain) and represent fundamental molecules above all for the constitution "of the polar liquid mosaic", typical of cell membranes, and the structuring of the myelin sheaths of the nervous system. The organism is also able to produce them autonomously, therefore, from a food point of view they are considered GOOD FATS but not for this ESSENTIAL.
Esters of sterols: See above: Sterols.
Waxes:
They are not important lipids from a nutritional point of view but are sometimes used as additives (carnauba wax and beeswax). In nutrition, the most famous wax is the bloom, a natural protective film of the berries; on the contrary, the beeswax is separated from honey and therefore is not a significant food component. Waxes are not a BAD FAT but neither are a GOOD or ESSENTIAL FAT.
