Lipids and cardiovascular diseases
The excess LDL present in the plasma infiltrates under the arteries, they are modified (oxidized) and begin the atherosclerotic process, a veritable antechamber of cardiovascular diseases.
Fibrinolysis protects us from these dangerous events; for this reason an excess of triglycerides in the blood, making this defense mechanism less efficient, significantly increases the risk of developing cardiovascular diseases.
Saturated dietary fatty acids increase cholesterol levels, so they are atherogenic. It is useful to remember, in this regard, that saturated fatty acids do not all have the same atherogenic power. The most dangerous ones are the palmitic (C16: 0), the myristic (C14: 0), while the lauric (C12: 0) seems to increase the total cholesterol levels above all by raising the HDL fraction (positive aspect). Stearic acid (C18: 0), on the other hand, although saturated, is not very atherogenic since the organism desaturates rapidly forming oleic acid.
Even medium chain fatty acids seem to have no atherogenic power.
Saturated fatty acids are found mainly in dairy products, eggs, meat and some vegetable oils (coconut and palm). The latter are abundantly used by the food industries, especially in the preparation of confectionery and bakery products.
Saturated fatty acids can be obtained artificially, through industrial processes based on the hydrogenation of vegetable oils (as happens, for example, in the production of margarine). These fatty acids are called trans because, unlike naturally occurring cis fatty acids, the two hydrogens bound to the carbons involved in the double bond are arranged on opposite planes.
Trans fatty acids are harmful to health, as they increase bad LDL cholesterol levels and reduce those of good HDL cholesterol.
Trans fatty acids are present in numerous food products of industrial origin, where from the end of 2014 they are compulsorily indicated on the label with the expression « totally or partially hydrogenated fat ». However, even if not hydrogenated, vegetable fats are generally prepared with tropical oils, rich in saturated fatty acids and therefore far from being considered healthy.
Functions of the main unsaturated fatty acids
Omega-6 polyunsaturated fatty acids lower cholesterol, reducing plasma LDL levels. This benefit, however, is partly mitigated by the fact that the same omega-6 fatty acids also slightly reduce the "good" HDL cholesterol.
Oleic acid (olive oil), on the other hand, reduces LDL cholesterol levels (albeit to a lesser extent than omega-6) without affecting the HDL-cholesterol percentage. This fatty acid, although not as essential as the other two, is therefore very important for our well-being. Oleic acid is found in numerous seasonings of vegetable origin and especially in olive oil which, also for this reason, represents one of the best condiments to use in the kitchen.
Omega-3 polyunsaturated fatty acids lower plasma triglyceride levels, interfering with their hepatic incorporation into VLDL. For this reason they have an important antithrombotic action (we remind, in fact, that high levels of triglycerides in the blood reduce the fibrinolysis process, which is responsible for the dissolution of intravasal clots; for this reason, hypertriglyceridemia is accompanied by an increased risk of cardiovascular diseases) .
All this explains why every day, through TV and newspapers, doctors and nutritionists emphasize the importance of regular consumption of foods rich in omega-three (fish and flaxseed), in order to control blood cholesterol levels, triglycerides and, together with them, the risk of cardiovascular diseases.
NOTE : To obtain benefits from the correction of the food lipids consumed, it is necessary to replace the omega-6 and omega-3 to saturated and hydrogenated fats; their contribution, therefore, must not be additive but substitute. Furthermore, it is essential to respect the overall caloric constraint: a diet that is too rich in fats and calories, even if composed of lipids of excellent quality, in fact risks nullifying the protective effect of the latter on cardiovascular risk.
Lipids and cancer
High fat consumption increases the incidence of various cancers (breast, colon, prostate and pancreas). Scholars, for some time, have in fact noticed that the incidence of tumors increases in groups of populations that pass from a low-fat diet to a hyperlipidic one. This fact was found especially in the Japanese who, after moving to the United States and having adopted the typical hyperlipidic diet of this country, suffered a greater incidence of tumors.
Lipids are believed to be promoters and non-initiators of the tumor process. In other words, a high-fat diet would not start the tumor, but would stimulate the proliferation of existing cancer cells.
The amount of lipids consumed, rather than quality, would have the greatest impact on tumor incidence.
Lipids and obesity
It is established that a high fat intake predisposes to obesity for several reasons:
lipids are more energetic than other nutrients.
Taking too much fat does not increase their oxidation, unlike carbohydrates which, if consumed in excess, promote, within certain limits, an increase in the body's ability to oxidize them.
Lipids are the nutrients with the lowest thermogenic effect (each time we eat, the energy expenditure increases; this increase is maximum for proteins - 30% of the protein caloric intake -, intermediate for carbohydrates - 7% - and very low for lipids - 2-3% of the energy consumed -)
Lipids and immune function
Nutritional deficiencies lower the immune system. However, even those who consume excess fat run the same risks as a malnourished individual. Although it may seem a paradox, even dietary excess (lipid species) therefore causes a lower immune response.
How many lipids do you take daily?
It is agreed that the ideal amount of lipids in the diet is 25-35% of the total caloric intake. For what has been said so far, it is advisable not to exceed the upper limit, but also not to fall below the minimum value, both because it would meet nutritional deficiencies, and because the diet would become so unsatisfactory as to be abandoned easily.
As for cholesterol, it is advised not to take more than 300 mg a day. In the presence of cardiovascular diseases or high family predisposition to these diseases, the cholesterol intake should be more contained.
