Introduction
The cholesterol contained in the diet represents about 1/3 of the total blood cholesterol.
In foods, the cholesterol content is assessed as a whole, regardless of whether it is esterified, not esterified or bound to a lipoprotein; on the contrary, in our organism what most influences the state of health is its METABOLISM, that is the quantity and the chemical nature of the cholesterol transport lipoproteins.
Lipoproteins
What They Are, Functions, Blood Values
Lipoproteins are divided into the following types:
- Chylomicrons;
- Very Low Density Lipoprotein (VLDL);
- Intermediate Density Lipoprotein (IDL o remnant);
- LDL (Low Density Lipoprotein);
- High Density Lipoprotein (HDL);
HDL lipoproteins are responsible for transporting cholesterol from the periphery to the liver, performing an atherosclerotic protective function; on the contrary, LDLs transport cholesterol from the liver to the tissues and their permanence in the blood favors the storage of fats in the arteries, predisposing to atherosclerosis.
I blood limits of the lipoproteins are the following:
- Total cholesterol <200 mg / dL;
- LDL < 129 mg/dL;
- Human HDL> 40 mg / dL;
- HDL donna >50 mg/dL;
- OPTIMUM LDL / HDL RATIO ≤ 3.
Regardless of genetics and family history, a subject who has elevated total cholesterol or a non-optimal LDL / HDL ratio, must necessarily intervene quickly on the diet before starting a drug therapy.
Diet and Cholesterol
Cholesterol is a lipid contained in foods of animal origin; the foods that contain the most belong to the category:
- Of eggs (371mg / 100g);
- Dairy products, especially butter (250mg / 100g), cream of milk (43mg / dL) and aged cheeses (fontina 82mg / 100g, Parmesan 91mg / 100g, etc.);
- Of fatty meats and sausages (Lamb 70-80mg / 100g, Salami 80-100mg / 100g) and some offal (bovine liver 191mg / 100g).
Importance of Saturated and Unsaturated Fats
In addition to the amount of total cholesterol, saturated fats and hydrogenated (trans-) fats contribute decisively to the increase in total (and LDL) cholesterolemia. This occurs due to their negative influence on the expression of LDL uptake receptors, which consequently tend to accumulate.
On the contrary, the prevalence in the diet of unsaturated-polyunsaturated fatty acids (but also monounsaturated omega 9 / oleic acid) favors the removal of LDL and increases the fraction of HDL.
- This translates into the need to:
- Limit the consumption of animal fats (such as butter, lard, cuts of meat higher in fat, and cheeses);
- Minimize the consumption of hydrogenated vegetable fats (contained in many margarines and products that contain them, such as pastry);
- Prefer the use of raw vegetable seasonings, such as olive oil (palm and palm kernel oil to be avoided), and consume at least three portions of fish a week.
Absorption of Cholesterol and Bile Salts
One of the individual factors that significantly affects cholesterolemia is the ratio of cholesterol excreted with the bile to that absorbed / reabsorbed by the intestine.
Dietary cholesterol is contained in fatty foods of animal origin; food lipids, to be digested and absorbed, must be emulsified by the bile. The emulsifying agent of bile is composed largely of cholesterol deriving from the bloodstream. In the digestive tract, a part of this lipid emulsion (alimentary + biliary) is reabsorbed and the cholesterol with it; the intestinal ability to reabsorb cholesterol determines one of the subjective factors that affect cholesterolemia.
Importance of Fiber and Phytosterols
This process can also be modified with nutrition; some dietary components, such as soluble dietary fiber (mainly contained in vegetables and fruit), phytosterols (plant sterols) and lecithin (mainly contained in legumes), have the ability to gel the feces and bind cholesterol (together with acids fats) hindering their absorption / reabsorption.
- This means that fruit, vegetables and / or legumes must also be associated with each meal containing cholesterol in order to reduce intestinal uptake.
Subjects who undergo a diet hypocholesterolemic They MUST anyway ensure the intake of fiber, lecithin e phytosterols, since, if it is true that bile represents a route of excretion of circulating cholesterol (most of which is produced by the liver), by hindering its reabsorption it is possible to further reduce the levels of total cholesterol.
Importance of Antioxidants
We remind you that the oxidation of LDL, caused by the excess of free radicals (smoke, alcohol, pollutants, etc.) and / or by the lack of antioxidants (diet lacking in vitamins, polyphenols, etc.) and / or by chronic metabolic inflammation (at which also contribute to type 2 diabetes with the relative blood protein glycation), cause a worsening of cholesterol metabolism increasing the risk of atherosclerosis.
This results in the need to maintain a high intake of antioxidants in the diet, thanks to the frequent consumption of fresh fruit and vegetables, possibly in season, limiting sugary fruit especially in the presence of overweight or diabetes.
