Foods rich in fats or lipids are all those foods which, from a chemical and nutritional standpoint, are distinguished by their high intake of triglycerides and / or cholesterol.
Triglycerides and cholesterol
Fats are substances soluble in organic solvents and not very soluble in water; it is difficult to define the functional unit of fats, as they represent a fairly heterogeneous group of all different molecules.
Classification of main fats
Containing glycerol: Neutral fats (monoglycerides, di-glycerides and triacylglycerols or triglycerides ), glycerol ethers (glycosylglycerides and phosphoglycerides; phosphatides; phosphatidylglycerols; phosphoinositides)
NOT containing glycerol: sphingolipids (ceramides, sphingomyelins, glycosphingolipids), aliphatic alcohols and waxes, terpenes and steroids ( cholesterol ), fatty acids
- Triglycerides: triglycerides or triacylglycerols are neutral lipids containing fatty acids bound to a glycerol molecule; in nutrition they supply 9 kcal per gram and represent about 25-30% of the energy ration. Their composition in fatty acids represents a characteristic element between a good and a bad diet; in fact, the fatty acids that compose them are usually different from each other (even if on average they contain 16-18 more or less saturated carbon atoms) and their nature distinguishes their peculiarities as well as their nutritional impact.
- Cholesterol: cholesterol is the most abundant steroid in the body and is NOT essential as about 70% of the total is derived from endogenous Acetyl-CoA. It is a fundamental substrate for the synthesis of steroid hormones and vitamin D also represents a structural element of cell membranes; the only way of eliminating cholesterol are feces, in which it is poured through bile salts (compounds responsible for the digestion of food lipids).
- Essential components: among the lipid molecules there are also essential nutrients, that is that the organism is not able to produce independently. These include the polyunsaturated fatty acids of the omega3 and omega6 series, and the LIPOsoluble vitamins: A, D, E, K.
Distinction of foods rich in fat
Among the foods rich in fat it is possible to make a distinction between those rich in triglycerides only, those rich in triglycerides and cholesterol, and those containing considerable amounts of cholesterol but proportionally not as rich in triglycerides.
Foods rich in triglycerides
Foods rich in triglycerides only are mainly seasoning vegetable oils. This food category is distinguished by a triglyceride intake of 99.9% of the total weight and only traces of water. They supply 899kcal per 100g of edible portion respectively but their qualitative composition can vary significantly depending on the extraction food.
The oils differ from each other in the nature of the fatty acids contained which, as anticipated, determines the useful chemical-physical characteristics of the various food preparations. For example, oils rich in monounsaturated and saturated fatty acids (hydrogenated and otherwise) but poor in polyunsaturated fatty acids lend themselves much more than others to frying, as they have a rather high smoke point (PF). This is the case of palm oil (PF 240 ° C) but also of extra virgin olive oil (PF 210 ° C), the latter limitedly used in frying due to decidedly higher costs compared to tropical extracts or of seeds. The same applies to oils useful for preserving foodstuffs in oil; also in this case the content of polyunsaturated fatty acids plays against the food process: as these nutrients are easily peroxidable, they would negatively contribute to the preservation of the product, facilitating their rancidity (lipid peroxidation). Therefore the grapeseed, soy or sunflower oils are not indicated for preservation in oil, while the extra virgin olive oil (also rich in natural antioxidants: vitamin E and polyphenols) stands out once again for its high wholesomeness even in frequent use. On the other hand, when using raw it is possible to range over many products deriving from numerous raw materials, the important thing is that the oil in question is obtained through the COLD PRESSING (such as extra virgin olive oil, soy, of linen etc); this is an absolutely fundamental requirement, as the main nutritional characteristic of the condiment oil is the contribution of essential fatty acids (omega6 and omega3 family) which, being easily thermolabile, could deteriorate following the extraction process (squeezing with hot).
There are also other foods rich in triglycerides but free of cholesterol; among these we remember:
- The olive, a fruit from which it is possible to extract oil
- Avocado, an exotic fruit with a very high SATURO lipid content
- Coconut, an exotic fruit with a very high lipid content of medium chain fatty acids (similar to those of breast milk), from which it is possible to extract oil
- Peanut, a "toasted" legume from which oil can be extracted
- Some achenes better known as nuts: walnuts, almonds, hazelnuts, pecans, etc.
As already stated, foods rich in triglycerides alone are typically of vegetable origin and their importance in the diet varies according to the specific product and its characteristics, or rather according to the type of fatty acids that compose them. We also remember that among all the foods mentioned above, products that are not actually rich in eicosapentaenoic acid (essential fatty acid of the omega3 category - EPA), on the other hand, are very present in various foods of animal origin.
Foods rich in triglycerides and cholesterol
Foods rich in triglycerides and cholesterol are products of animal origin; it should be emphasized that, apart from some special cases, these are also characterized by SATURO type fatty acids, therefore typically hyper-cholesterol-lowering and potentially harmful to the cardiovascular system.
Foods high in fat, especially triglycerides and cholesterol, are ESPECIALLY:
- Some offal or fifth-fourth components: these include the brain (also rich in essential fatty acids and phospholipids) and the liver.
- Cream, mascarpone and aged cheeses (all): obviously, there is a certain variability in the total content of fat that depends on the raw material used for making cheese: goat's milk, buffalo milk, sheep's milk or cow's milk, whole, skimmed or partially skimmed. Some examples of mature cheeses are: Parmigiano Reggiano, Grana Padano, Pecorino (all), Emmenthal, Edamer, whole milk provola, etc.
- Butter, lard, lard, suet, tallow and pork rind.
- White meat WITH SKIN: in itself white meat is recommended in the hypercholesterolemic diet as it is distinguished by an excellent "thinness"; the situation is reversed if it is consumed WITH SKIN, which contains very high portions of both cholesterol and triglycerides.
- Fatty meats, bagged and salted but NOT DEGREASED: all. From bacon to sausage; from ribs to mortadella.
- Some fish and all the eggs of fishery products: some examples are the eel (with the due differences due to the origin, size and season of capture), the tuna belly (although rich in EPA and low in saturated fatty acids ), large specimens of salmon (although very rich in EPA and low in saturated fatty acids), caviar, lumpfish roe, bottarga, sea urchins, flying fish roe (widely used in the preparation of raw Japanese food). NB. The skin of the fish, like that of white meat, contributes significantly to raising the levels of total fat introduced with food.
- Egg yolk: strongly used in pastry preparations such as custard, custard etc.
Foods rich in cholesterol but poor in triglycerides
Surprisingly, some fishery derivatives fall into this category; for the uninitiated, it is correct to say that the population does NOT make sufficient consumption of fish (especially blue fish), but in this category the shellfish and crustaceans do NOT RETURN and, on the contrary, are widely consumed globally. BIVALVI molluscs and crustaceans are distinguished by a notable intake of cholesterol in relation to a not excessive triglyceride content; in particular we mention:
- Mussels and oysters: especially during reproduction these organisms modify their cholesterol content to comply with the hormonal cycle of fertilization
- Shrimps, crabs and all derivatives: including crab meat, crab claws (fried), surimi, prawn tails, peeled shrimp etc.
NB . The list has ONLY mentioned foods rich in fats of which nutritional values are known; however, it can be deduced that also other "similar" products and belonging to the same category / genus (such as scampi with respect to the crustaceans mentioned in the last paragraph) can boast the same chemical-nutritional characteristics and therefore must be treated as such.
Bibliography:
- The molecular bases of nutrition - G. Arienti - Piccin - pag 131
- Levels of Recommended Intake of Nutrients for the Italian Population ( LARN ) - Italian Society of Human Nutrition (SINU)
