Definition of indicators lipid profile blood is necessary for the diagnosis, treatment and prevention of cardiovascular diseases. The most important mechanism for the development of such a pathology is the formation of atherosclerotic plaques on the inner wall of blood vessels. Plaques are accumulations of fat-containing compounds (cholesterol and triglycerides) and fibrin. The higher the concentration of lipids in the blood, the probable occurrence atherosclerosis. Therefore, it is necessary to systematically take a blood test for lipids (lipid profile), this will help to identify abnormalities in a timely manner. fat metabolism from the norm.
Lipidogram - a study that determines the level of lipids of various fractions
Atherosclerosis is dangerous due to the high probability of complications - stroke, myocardial infarction, gangrene lower limbs. These diseases often result in disability of the patient, and in some cases, death.
The role of lipids
Functions of lipids:
- Structural. Glycolipids, phospholipids, cholesterol are the most important components of cell membranes.
- Thermal insulation and protective. Excess fat is deposited in subcutaneous fat, reducing heat loss and protecting internal organs. If necessary, the lipid supply is used by the body to obtain energy and simple compounds.
- Regulatory. Cholesterol is necessary for the synthesis of adrenal steroid hormones, sex hormones, vitamin D, bile acids, is part of the myelin sheaths of the brain, and is needed for the normal functioning of serotonin receptors.
Lipidogram
A lipidogram can be prescribed by a doctor both if an existing pathology is suspected and for preventive purposes, for example, during a medical examination. It includes several indicators that allow you to fully assess the state of fat metabolism in the body.
Lipid profile indicators:
- Total cholesterol (TC). This the most important indicator The lipid spectrum of the blood includes free cholesterol, as well as cholesterol contained in lipoproteins and associated with fatty acids. A significant portion of cholesterol is synthesized by the liver, intestines, and gonads; only 1/5 of the TC comes from food. With normally functioning mechanisms of lipid metabolism, a slight deficiency or excess of cholesterol supplied from food is compensated by an increase or decrease in its synthesis in the body. Therefore, hypercholesterolemia is most often caused not by excess cholesterol intake from foods, but by a failure of the fat metabolism process.
- High density lipoproteins (HDL). This indicator has an inverse relationship with the likelihood of developing atherosclerosis - increased level HDL is considered an antiatherogenic factor. HDL transports cholesterol to the liver, where it is utilized. Women have higher HDL levels than men.
- Low density lipoproteins (LDL). LDL carries cholesterol from the liver to tissues, otherwise known as “bad” cholesterol. This is due to the fact that LDL is capable of forming atherosclerotic plaques, narrowing the lumen of blood vessels.
This is what an LDL particle looks like
- Very low density lipoproteins (VLDL). The main function of this group of particles, heterogeneous in size and composition, is the transport of triglycerides from the liver to tissues. A high concentration of VLDL in the blood leads to clouding of the serum (chylosis), and the possibility of the appearance of atherosclerotic plaques also increases, especially in patients with diabetes mellitus and kidney pathologies.
- Triglycerides (TG). Like cholesterol, triglycerides are transported through the bloodstream as part of lipoproteins. Therefore, an increase in the concentration of TG in the blood is always accompanied by an increase in cholesterol levels. Triglycerides are considered the main source of energy for cells.
- Atherogenic coefficient. It allows you to assess the risk of developing vascular pathology and is a kind of summary of the lipid profile. To determine the indicator, you need to know the value of TC and HDL.
Atherogenic coefficient = (TC - HDL)/HDL
Optimal blood lipid profile values
| Floor | Indicator, mmol/l | |||||
| OH | HDL | LDL | VLDL | TG | CA | |
| Male | 3,21 — 6,32 | 0,78 — 1,63 | 1,71 — 4,27 | 0,26 — 1,4 | 0,5 — 2,81 | 2,2 — 3,5 |
| Female | 3,16 — 5,75 | 0,85 — 2,15 | 1,48 — 4,25 | 0,41 — 1,63 | ||
It should be taken into account that the value of the measured indicators may vary depending on the units of measurement and the analysis methodology. Normal values also vary depending on the age of the patient; the above indicators are averaged for persons 20 - 30 years old. The level of cholesterol and LDL in men after 30 years tends to increase. In women, indicators increase sharply with the onset of menopause, this is due to the cessation of the antiatherogenic activity of the ovaries. The interpretation of the lipid profile must be carried out by a specialist, taking into account the individual characteristics of the person.
A study of blood lipid levels can be prescribed by a doctor to diagnose dyslipidemia, assess the likelihood of developing atherosclerosis, in some chronic diseases (diabetes mellitus, kidney and liver diseases, thyroid gland), and also as a screening study for early detection persons with lipid profile deviations from the norm.
The doctor gives the patient a referral for a lipid profile
Preparing for the study
Lipid profile values can fluctuate not only depending on the gender and age of the subject, but also on the impact on the body of various external and internal factors. To minimize the likelihood of an unreliable result, you must adhere to several rules:
- You should donate blood strictly in the morning on an empty stomach; in the evening of the previous day, a light dietary dinner is recommended.
- Do not smoke or drink alcohol the night before the test.
- Avoid 2-3 days before donating blood stressful situations and intense physical activity.
- Stop using all medications and dietary supplements except those that are vital.
Methodology
There are several methods laboratory evaluation lipid profile. IN medical laboratories analysis can be carried out manually or using automatic analyzers. The advantage of an automated measurement system is the minimal risk of erroneous results, the speed of obtaining analysis, high accuracy research.
The analysis requires the patient's venous blood serum. Blood is drawn into a vacuum tube using a syringe or vacutainer. To avoid clot formation, the blood tube should be inverted several times and then centrifuged to obtain serum. The sample can be stored in the refrigerator for 5 days.
Taking blood for lipid profile
Nowadays, blood lipids can be measured without leaving home. To do this, you need to purchase a portable biochemical analyzer that allows you to assess the level of total cholesterol in the blood or several indicators at once in a matter of minutes. A drop is needed for research capillary blood, it is applied to the test strip. Test strip is saturated special composition, for each indicator it is different. The results are read automatically after inserting the strip into the device. Thanks to the small size of the analyzer and the ability to operate on batteries, it is convenient to use at home and take with you on a trip. Therefore, persons with a predisposition to cardiovascular diseases It is recommended to have it at home.
Interpretation of results
The most ideal result of the analysis for the patient will be a laboratory conclusion that there are no deviations from the norm. In this case, a person does not have to worry about the state of his circulatory system - the risk of atherosclerosis is practically absent.
Unfortunately, this is not always the case. Sometimes the doctor, after reviewing the laboratory data, makes a conclusion about the presence of hypercholesterolemia. What it is? Hypercholesterolemia is an increase in the concentration of total cholesterol in the blood above normal values, and there is a high risk of developing atherosclerosis and related diseases. This condition may be due to a number of reasons:
- Heredity. Science knows cases of familial hypercholesterolemia (FH), in such a situation the defective gene responsible for lipid metabolism is inherited. Patients experience constantly elevated levels of TC and LDL; the disease is especially severe in the homozygous form of FH. Such patients have an early onset of coronary artery disease (at the age of 5-10 years); in the absence of proper treatment, the prognosis is unfavorable and in most cases ends in death before reaching 30 years of age.
- Chronic diseases. Elevated cholesterol levels occur with diabetes mellitus, hypothyroidism, kidney and liver pathologies, is caused by lipid metabolism disorders due to these diseases.
For patients suffering from diabetes, it is important to constantly monitor cholesterol levels
- Poor nutrition. Long-term abuse of fast food, fatty, salty foods leads to obesity, and, as a rule, there is a deviation in lipid levels from the norm.
- Bad habits. Alcoholism and smoking lead to disruptions in the mechanism of fat metabolism, as a result of which lipid profile indicators increase.
With hypercholesterolemia, it is necessary to adhere to a diet with limited fat and salt, but in no case should you completely abandon all foods rich in cholesterol. Only mayonnaise, fast food and all products containing trans fats should be excluded from the diet. But eggs, cheese, meat, sour cream must be present on the table, you just need to choose products with a lower percentage of fat content. Also important in the diet is the presence of greens, vegetables, cereals, nuts, and seafood. The vitamins and minerals they contain perfectly help stabilize lipid metabolism.
An important condition for normalizing cholesterol is also giving up bad habits. Constant physical activity is also beneficial for the body.
In case if healthy image life in combination with diet did not lead to a decrease in cholesterol, it is necessary to prescribe appropriate drug treatment.
Drug treatment of hypercholesterolemia includes the prescription of statins
Sometimes specialists are faced with a decrease in cholesterol levels - hypocholesterolemia. Most often, this condition is caused by insufficient intake of cholesterol from food. Fat deficiency is especially dangerous for children; in such a situation, there will be a lag in physical and mental development, cholesterol is vital for a growing body. In adults, hypocholesteremia leads to disturbances in the emotional state due to disruptions in work nervous system, problems with reproductive function, decreased immunity, etc.
Changes in the blood lipid profile inevitably affect the functioning of the entire body as a whole, so it is important to systematically monitor fat metabolism indicators for timely treatment and prevention.
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The site provides background information for informational purposes only. Diagnosis and treatment of diseases must be carried out under the supervision of a specialist. All drugs have contraindications. Consultation with a specialist is required!
Lipids in nutrition
Along with proteins and carbohydrates, lipids are the main nutritional elements that make up a significant part of food. The intake of lipids into the body from food has a significant impact on human health in general. Insufficient or excessive consumption of these substances can lead to the development of various pathologies. Most people eat a fairly varied diet, and their body gets all the necessary lipids. It should be noted that some of these substances are synthesized by the liver, which partly compensates for their lack in food. However, there are also essential lipids, or rather their components are polyunsaturated fatty acids. If they do not enter the body with food, over time this will inevitably lead to certain disorders.
Most of the lipids in food are used by the body to produce energy. This is why when fasting a person loses weight and becomes weaker. Deprived of energy, the body begins to consume lipid reserves from subcutaneous fat.
Thus, lipids play a very important role in healthy human nutrition. However, for some diseases or disorders, their quantity should be strictly limited. Patients usually learn about this from their attending physician ( usually a gastroenterologist or nutritionist).
Energy value of lipids and their role in diet
The energy value of any food is calculated in calories. A food product can be broken down according to its composition into proteins, carbohydrates and lipids, which together make up the bulk. Each of these substances breaks down in the body, releasing a certain amount of energy. Proteins and carbohydrates are digested more easily, but the breakdown of 1 g of these substances releases about 4 Kcal ( kilocalories) energy. Fats are more difficult to digest, but the breakdown of 1 g releases about 9 kcal. Thus, energy value lipids is the highest.In terms of energy release, triglycerides play the largest role. Saturated acids, included in these substances, are absorbed by the body by 30–40%. Monounsaturated and polyunsaturated fatty acids are completely absorbed by a healthy body. Adequate lipid intake allows carbohydrates and proteins to be used for other purposes.
Plant and animal lipids
All lipids entering the body with food can be divided into animal substances and plant origin. From a chemical point of view, the lipids that make up these two groups differ in their composition and structure. This is explained by differences in the functioning of cells in plants and animals.Examples of plant and animal lipid sources
Each lipid source has certain advantages and disadvantages. For example, animal fats contain cholesterol, which is not found in plant foods. In addition, animal products contain more lipids and are more energy efficient to consume. At the same time, excess animal fat increases the risk of developing a number of diseases associated with lipid metabolism in the body ( atherosclerosis, cholelithiasis, etc.). Plant foods contain fewer lipids, but the body cannot synthesize them on its own. Even a small amount of seafood, citrus fruits or nuts supplies enough polyunsaturated fatty acids, which are vital for humans. At the same time, a small proportion of lipids in plants cannot fully cover the body’s energy costs. That is why, to maintain health, it is recommended to make your diet as varied as possible.
What is the body's daily requirement for lipids?
Lipids are the main suppliers of energy to the body, but their excess can be harmful to health. First of all, this concerns saturated fatty acids, most of which are deposited in the body and often lead to obesity. The optimal solution is to maintain the required proportions between proteins, fats and carbohydrates. The body must receive the same number of calories that it expends during the day. This is why lipid intake rates may vary.The body's need for lipids can be influenced by the following factors:
- Body weight. Overweight people have to expend more energy. If they are not going to lose weight, then the need for calories and, accordingly, lipids will be slightly higher. If they want to lose weight, then, first of all, they need to limit fatty foods.
- Loads during the day. People doing heavy lifting physical work, or athletes need a lot of energy. If the average person has 1500 - 2500 calories, then for miners or loaders the norm can reach 4500 - 5000 calories per day. Of course, the need for lipids also increases.
- Nature of nutrition. Every country and every people has its own food traditions. When calculating the optimal diet, you need to take into account exactly what foods a person usually consumes. For some peoples, fatty foods are a kind of tradition, while others, on the contrary, are vegetarians, and their lipid intake is kept to a minimum.
- Presence of concomitant pathologies. For a number of disorders, lipid intake should be limited. First of all, we are talking about diseases of the liver and gall bladder, since these organs are responsible for the digestion and absorption of lipids.
- The age of the person. IN childhood Metabolism is faster and the body requires more energy for normal growth and development. In addition, children usually do not have serious problems with the gastrointestinal tract, and they digest any food well. It should also be taken into account that infants receive an optimal set of lipids through breast milk. Thus, age greatly influences the rate of fat intake.
- Floor. It is believed that on average a man consumes more energy than a woman, so the norm of fat in men's diet is slightly higher. However, in pregnant women, the need for lipids increases.
It is difficult for a person to make the necessary calculations on his own and take into account all the factors to select the optimal diet. To do this, it is better to consult a nutritionist or food hygiene specialist. After a short survey and clarification of the nature of nutrition, they will be able to create an optimal daily diet that the patient will adhere to in the future. They can also recommend specific foods that contain essential lipids.
Which foods mainly contain lipids ( milk, meat, etc.)?
Almost all food products contain lipids in varying quantities. However, in general, animal products are richer in these substances. In plants, the mass fraction of lipids is minimal, but the fatty acids included in such lipids are most important for the body.The amount of lipids in a particular product is usually indicated on the product packaging in the section “ the nutritional value" Most manufacturers are required to inform consumers about mass fraction proteins, carbohydrates and fats. In self-prepared food, the amount of lipids can be calculated using special tables for nutritionists, which indicate all the main products and dishes.
Mass fraction of lipids in staple foods
In most products of plant origin ( vegetables, fruits, herbs, root vegetables) the mass fraction of fats is no more than 1 – 2%. The exceptions are citrus fruits, where the proportion of lipids is slightly higher, and vegetable oils, which are a concentrate of lipids.
Are there essential lipids, and what are their most important sources?
The structural unit of lipids is fatty acids. Most of these acids can be synthesized by the body ( mainly by liver cells) from other substances. However, there are a number of fatty acids that the body cannot produce on its own. Thus, lipids containing these acids are essential.Most of the essential lipids are found in foods of plant origin. These are monounsaturated and polyunsaturated fatty acids. Body cells cannot synthesize these compounds, since the metabolism of animals is very different from that of plants.
Essential fatty acids and their main dietary sources
For a long time, the above fatty acids were equated in importance to vitamins for the body. Sufficient consumption of these substances strengthens the immune system, accelerates cell regeneration, and reduces inflammatory processes, promotes the conduction of nerve impulses.
What does a lack or excess of lipids in the diet lead to?
Both deficiency and excess of lipids in the diet can seriously affect the health of the body. IN in this case It's not a one-time thing large quantity fat ( although this may cause certain consequences), but about the systematic abuse of fatty foods or prolonged fasting. At first, the body is quite capable of successfully adapting to a new diet. For example, if there is a lack of lipids in food, the most important substances for the body will still be synthesized by the body’s own cells, and energy needs will be covered by the breakdown of fat reserves. If there is an excess of lipids in the diet, a significant part will not be absorbed in the intestines and will leave the body with fecal matter, and some of the lipids that enter the blood will be transformed into adipose tissue. However, these adaptation mechanisms are temporary. Moreover, they only work well in healthy body.Possible consequences of lipid imbalance in the diet
Blood and plasma lipids
A significant portion of lipids are present in the blood in various forms. Most often these are compounds of lipids with other chemicals. For example, triglycerides and cholesterol are transported primarily as lipoproteins. The levels of various lipids in the blood can be determined using biochemical blood tests. This makes it possible to identify a number of disorders and suspect corresponding pathologies. Triglycerides
Triglycerides perform mainly energy function. They enter the body with food, are absorbed in the intestines and are carried throughout the body through the blood in the form of various compounds. The normal level is considered to be 0.41 - 1.8 mmol/l, but it can fluctuate within significant limits. For example, after consuming a large amount fatty foods The level of triglycerides in the blood may increase 2–3 times.Free fatty acids
Free fatty acids enter the blood as a result of the breakdown of triglycerides. Normally, they are deposited in adipose tissue. Modern research showed a relationship between the level of free fatty acids in the blood and some pathological processes. For example, in people with high concentration fatty acids ( on an empty stomach) insulin is produced worse, so the risk of developing diabetes is higher. The normal content of fatty acids in the blood of an adult is 0.28 – 0.89 mmol/l. In children, the normal limits are wider ( up to 1.10 mmol/l).Cholesterol
Cholesterol is one of the most important lipids in the human body. It is part of many cellular components and other substances, influencing a variety of processes. An excess or deficiency of this substance or disruption of its absorption by the body can lead to the development of serious diseases.In the human body, cholesterol performs the following functions:
- imparts rigidity to cell membranes;
- takes part in the synthesis of steroid hormones;
- is part of bile;
- participates in the absorption of vitamin D;
- regulates the permeability of the walls of certain cells.
Lipoproteins ( lipoproteins) and their factions ( low density, high density, etc.)
The term lipoproteins or lipoproteins refers to a group of complex protein compounds that transport lipids in the blood. Some lipoproteins are fixed in cell membranes and perform a number of functions related to cell metabolism.All blood lipoproteins are divided into several classes, each of which has its own characteristics. The main criterion by which lipoproteins are distinguished is their density. According to this indicator, all these substances are divided into 5 groups.
There are the following classes ( factions) lipoproteins:
- High density. HDL) take part in the transfer of lipids from body tissues to the liver. From a medical point of view, they are considered useful because, due to their small size, they can pass through the walls of blood vessels and “cleanse” them of lipid deposits. Thus, high level HDL reduces the risk of developing atherosclerosis.
- Low density. LDL) transport cholesterol and other lipids from the liver ( places of their synthesis) to tissues. From a medical point of view, this fraction of lipoproteins is harmful, since it is LDL that promotes the deposition of lipids on the walls of blood vessels with the formation of atherosclerotic plaques. High LDL levels greatly increase the risk of developing atherosclerosis.
- Average ( intermediate) density. Intermediate density lipoproteins ( BOB) do not have significant diagnostic value, since they are an intermediate product of lipid metabolism in the liver. They also transport lipids from the liver to other tissues.
- Very low density. VLDL) transport lipids from the liver to tissues. They also increase the risk of developing atherosclerosis, but play a minor role in this process ( after LDL).
- Chylomicrons. Chylomicrons are significantly larger than other lipoproteins. They form in the walls small intestine and transport lipids supplied with food to other organs and tissues. In the development of various pathological processes these substances do not play a significant role.
Lipid analysis
Currently there are many laboratory tests, with which you can determine various lipids in the blood. Typically, venous blood is taken for this purpose. The patient is sent for analysis by the attending physician. The most important lipids ( total cholesterol, triglycerides) is determined in a biochemical blood test. If the patient needs a more detailed examination, the doctor indicates which lipids need to be determined. The analysis itself usually lasts several hours. Most laboratories provide results the next day. What is a lipid profile?
A lipidogram is a set of laboratory blood tests aimed at determining the level of lipids in the blood. This is the most useful research for patients with various lipid metabolism disorders, as well as for patients with atherosclerosis. Some indicators included in the lipid profile are also determined in a biochemical blood test, but in some cases this may not be enough to make an accurate diagnosis. A lipidogram is prescribed by the attending physician, based on the patient’s symptoms and complaints. This analysis is carried out by almost any biochemical laboratory.The lipidogram includes tests to determine the following blood lipids:
- Cholesterol. This indicator does not always depend on lifestyle and nutrition. A significant part of the cholesterol in the blood is the so-called endogenous cholesterol, which is produced by the body itself.
- Triglycerides. Triglyceride levels usually rise or fall in proportion to cholesterol levels. It may also increase after eating.
- Low density lipoproteins ( LDL). The accumulation of these compounds in the blood greatly increases the risk of developing atherosclerosis.
- High density lipoproteins ( HDL). These compounds are able to “clean” blood vessels from excess cholesterol and are beneficial for the body. Low HDL levels indicate that the body does not absorb fat well.
- Very low density lipoproteins ( VLDL). They have a secondary diagnostic value, but their increase along with an increase in LDL levels usually indicates atherosclerosis.
Before donating blood for a lipid profile, you should follow several simple rules. They will help avoid significant fluctuations in blood lipid levels and make the results more reliable.
Before taking the test, patients should consider the following recommendations:
- You can eat in the evening before the test, but you should not overeat fatty foods. It is better to stick to your usual diet.
- The day before the test, it is necessary to exclude various types of loads ( both physical and emotional), as they can lead to the breakdown of fat reserves in the body and increase blood lipid levels.
- In the morning, immediately before donating blood, you should not smoke.
- Regular use of a number of drugs also affects the level of lipids in the blood ( contraceptive drugs, hormonal drugs and etc.). It is not necessary to cancel them, but this fact must be taken into account when interpreting the results.
Normal blood lipid levels
The limits of the norm are somewhat different for all people. It depends on gender, age, availability chronic pathologies and a number of other indicators. However, there are certain limits, exceeding which clearly indicates the presence of problems. The table below shows generally accepted normal limits for various blood lipids.The limits of the norm are relative, and the patient himself cannot always draw the right conclusions when interpreting the results of the analysis. When reviewing the results, the attending physician will definitely take into account that during pregnancy the normal limits expand, as well as during fasting. Therefore, there is no need to panic if there are some deviations from the norm. In any case, the final conclusion must be made by the attending physician.
Diseases associated with lipid metabolism
There are quite a few diseases that are, to one degree or another, related to lipid metabolism in the body. Some of these pathologies cause an increase or decrease in various lipids in the blood, which is reflected in the tests. Other pathologies are a consequence of lipid imbalance. Lipid metabolism disorders ( dyslipidemia)
Excess or lack of lipids in the diet can lead to a variety of pathologies. In a healthy body that normally absorbs all incoming substances, this imbalance does not affect metabolic processes as much. For example, excess lipids do not always lead to obesity. To do this, a person must also have genetic predisposition, endocrine disorders, or he must lead sedentary lifestyle life. In other words, the amount of lipids in the diet in most cases is only one of many factors influencing the occurrence of pathology.Lipid imbalance can lead to the following pathologies:
- atherosclerosis ( as a result - aneurysms, coronary heart disease, hypertension or other problems with the cardiovascular system);
- skin problems;
- problems with the nervous system;
- a number of pathologies gastrointestinal tract (pancreatitis, cholelithiasis, etc.).
Causes of high and low lipid levels
The most common cause of elevated lipid levels in a blood test is errors made during blood donation. Patients do not donate blood on an empty stomach, which is why lipid levels do not have time to normalize, and the doctor may mistakenly suspect some problems. However, there are many pathologies that cause disturbances in blood lipids, regardless of nutrition.Pathological conditions associated with changes in the amount of lipids in the blood are called dyslipidemia. They are also divided into several types. If the level of triglycerides in the blood is elevated, they speak of hypertriglyceridemia ( synonym – hyperlipemia). If cholesterol levels increase, they speak of hypercholesterolemia.
Also, all dyslipidemias by origin are divided into the following groups:
- Primary. Primary dyslipidemias generally mean genetic diseases and deviations. As a rule, they are manifested by an excess or deficiency of any enzymes, which disrupts lipid metabolism. As a result, the amount of these substances in the blood decreases or increases.
- Secondary. Secondary dyslipidemias mean pathological conditions, in which the increase in blood lipids is a consequence of some other pathology. Thus, it is necessary to treat, first of all, this particular pathology, then the lipid level will gradually stabilize.
There are five main types of primary hyperlipoproteinemia ( elevated lipoprotein levels):
- Hyperchylomicronemia. With this disease, the level of triglycerides in the blood increases, while the level of other lipids usually remains within normal limits. Patients may experience paroxysmal abdominal pain, but without muscle tension abdominals. Xanthomas may appear on the skin ( formation of brown or yellowish color ). The disease does not lead to the development of atherosclerosis.
- Familial hyper-beta lipoproteinemia. With this pathology, the amount of beta-lipoproteins, and sometimes pre-beta-lipoproteins, increases. The analysis showed significantly higher cholesterol levels. Triglyceride levels may be normal or slightly elevated. Patients also develop xanthomatosis ( xanthomas on the skin). The risk of atherosclerosis increases significantly. With this disease, myocardial infarction is possible even at a young age.
- Familial hypercholesterolemia with hyperlipemia. The levels of both cholesterol and triglycerides in the blood are significantly elevated. Xanthomas are large and appear after 20–25 years. Increased risk of developing atherosclerosis.
- Hyper-pre-beta lipoproteinemia. In this case, the level of triglycerides increases, and the level of cholesterol remains within normal limits. The disease is often combined with diabetes, gout or obesity.
There are also secondary ( symptomatic) hyperlipoproteinemia in the following diseases:
- Diabetes. In this case, the excess lipids in the blood are explained by the transformation of excess carbohydrates.
- Acute pancreatitis. With this disease, the absorption of lipids is disrupted, and their level in the blood increases due to the breakdown of adipose tissue.
- Hypothyroidism. The disease is caused by a lack of thyroid hormones, which also regulate lipid metabolism in the body.
- Intrahepatic cholestasis and other liver pathologies. The liver takes part in the synthesis of most lipids, necessary for the body. With various hepatitis, bile outflow disorders and other pathologies of the liver and bile ducts, the level of lipids in the blood may increase.
- Nephrotic syndrome. This syndrome develops when the glomerular apparatus of the kidneys is damaged. Patients experience severe renal edema. The level of proteins in the blood drops, and the level of cholesterol increases significantly.
- Porphyria. Porphyria is a disease with a hereditary predisposition. In patients, the metabolism of a number of substances is disrupted, as a result of which porphyrins accumulate in the blood. In parallel, lipid levels may increase ( sometimes significantly).
- Some autoimmune diseases. In autoimmune diseases, antibodies produced by the body attack its own cells. In most cases, chronic inflammatory processes develop, which are associated with increased lipid levels.
- Gout. With gout, the metabolism of uric acid in the body is disrupted, and it accumulates in the form of salts. This is partly reflected in lipid metabolism, although their level in this case is slightly increased.
- Alcohol abuse. Alcohol abuse leads to pathologies of the liver and gastrointestinal tract. A number of enzymes may be activated that increase blood lipid levels.
- Taking certain medications. An increase in lipid levels can result, for example, from long-term use of oral contraceptives ( contraception ). Most often about this side effect mentioned in the instructions for the corresponding drug. Before taking the test, you should not take such drugs, or you should warn the treating physician about this so that he can correctly interpret the test results.
Also, increased levels of lipoproteins in the blood can be observed during pregnancy. This increase is usually minor. If lipid levels increase 2 to 3 times higher than normal, the likelihood of pregnancy should be considered in combination with other pathologies that cause increased lipid levels.
What diseases of the digestive system are associated with lipid metabolism?
A healthy digestive system is key good absorption lipids and other nutrients. A significant imbalance of lipids in food over a long period of time can lead to the development of certain gastric pathologies. One of the most common problems in cardiology is atherosclerosis. This disease occurs due to the deposition of lipids in blood vessels ( mainly in arteries). As a result of this process, the lumen of the vessel narrows and blood flow becomes difficult. Depending on which arteries are affected by atherosclerotic plaques, patients may experience various symptoms. The most common type is high blood pressure, ischemic disease hearts ( sometimes myocardial infarction), the appearance of aneurysms.Atherogenic lipids are those substances that lead to the development of atherosclerosis. It should be noted that the division of lipids into atherogenic and non-atherogenic is very arbitrary. In addition to the chemical nature of substances, the development of this disease Many other factors also contribute.
Atherogenic lipids more often lead to the development of atherosclerosis in the following cases:
- heavy smoking;
- heredity;
- diabetes;
- overweight ( obesity);
- sedentary lifestyle ( physical inactivity) and etc.
One of the biggest myths of modern humanity is the harmfulness of fats. Fat has become enemy number one. People spend dollars, rubles, euros, etc. to buy low-fat cookies, low-fat cola, tablets that can interfere with the absorption of fats, tablets that dissolve fats. People are on all sorts of fat-free diets.
But... In countries that are prosperous in all respects, the number of people suffering from obesity is steadily growing. The number of people suffering from cardiovascular diseases and diabetes mellitus, that is, diseases largely associated with excess weight, is growing. The war on fat continues...
So what's wrong?
Fact 1: Fats are good for you
The first and main mistake is to assume that all fats are the same; giving up all fats is a good thing. However, the education of the population is quite high, now many people know that unsaturated fats (mainly vegetable fats) are healthy. And the harmful ones are saturated ones (mainly animals).
Let's figure this out.
Saturated fats are structural components of cell membranes and participate in the biochemistry of the body. Therefore, completely abandoning them will lead to irreversible changes in health. Another thing is that their consumption must correspond age indicators. Children and adolescents need them in sufficient quantity, their consumption can be reduced with age.
Unsaturated fats - reduce the level of “bad” cholesterol, are necessary for the body to absorb certain vitamins (fat-soluble), and participate in metabolism. That is, the body also needs these fats.
A quick observation: saturated fats are solid, unsaturated fats are liquid.
According to physiological indicators for the average person, the ratio of saturated - unsaturated fats should be 1\3:2\3. Eating healthy fats is essential!
Trans fats are definitely harmful. They are also found in nature (for example, in natural milk), but for the most part they are formed from other (vegetable) fats, through hydrogenation (a method of processing fats to give them a solid form).
Fact 2: Body fat is not the result of eating fat.
What?! Of course, if you simply increase your fat intake without reducing other foods, you excess weight dial. The basis of maintaining a normal weight is balance. You should burn as many calories as you consume.
But diets with sharp restriction calorie intake can also lead to sudden weight gain after withdrawal. Why? The body received a command: hunger. This means we need to accumulate fats in reserve. Therefore, all food is processed and goes to the “depot” - fat deposits. At the same time, you may faint from hunger. Processed carbohydrates are stored in fat reserves.
Studies show that if a person is on a low-calorie, low-fat diet, then the few kilograms lost with great difficulty come back, even if you continue to “sit” on this diet.
In addition, people who consume low amounts of fat are prone to obesity.
And observations of patients in the USA revealed a picture that a decrease in the amount of fat from 40% (which is considered normal) to 33% in the diet is accompanied by an increase in overweight people.
Remember that unsaturated fats are involved in metabolism. The protein: fat: carbohydrate ratio for an adult should be approximately 14%: 33%: 53%.
Conclusion: An increase in unsaturated fats in food while maintaining the same calorie content will not lead to weight gain, but will contribute to improved health through metabolism.
Lipids- very diverse in their own way chemical structure substances characterized by varying solubility in organic solvents and, as a rule, insoluble in water. They play an important role in life processes. Being one of the main components of biological membranes, lipids affect their permeability, participate in the transmission of nerve impulses, and the creation of intercellular contacts.
Other functions of lipids are the formation of an energy reserve, the creation of protective water-repellent and thermally insulating covers in animals and plants, and the protection of organs and tissues from mechanical stress.
CLASSIFICATION OF LIPIDS
Depending on their chemical composition, lipids are divided into several classes.
- Simple lipids include substances whose molecules consist only of fatty acid (or aldehyde) residues and alcohols. These include
- fats (triglycerides and other neutral glycerides)
- waxes
- Complex lipids
- orthophosphoric acid derivatives (phospholipids)
- lipids containing sugar residues (glycolipids)
- sterols
- steroids
IN this section Lipid chemistry will be discussed only to the extent necessary to understand lipid metabolism.
If an animal or plant tissue treated with one or more (usually sequentially) organic solvents, for example chloroform, benzene or petroleum ether, then some of the material goes into solution. The components of such a soluble fraction (extract) are called lipids. The lipid fraction contains substances various types, most of which are presented in the diagram. Note that due to the heterogeneity of the components included in the lipid fraction, the term “lipid fraction” cannot be considered as a structural characteristic; it is only a working laboratory name for the fraction obtained during the extraction of biological material with low-polarity solvents. However, most lipids have some common structural features, determining their important biological properties and similar solubility.
Fatty acid
Fatty acids - aliphatic carboxylic acids- in the body they can be in a free state (trace amounts in cells and tissues) or act as building blocks for most classes of lipids. Over 70 different fatty acids have been isolated from the cells and tissues of living organisms.
Fatty acids found in natural lipids contain an even number of carbon atoms and have predominantly straight carbon chains. Below are the formulas for the most commonly found naturally occurring fatty acids.
Natural fatty acids, although somewhat arbitrarily, can be divided into three groups:
- saturated fatty acids [show]
- monounsaturated fatty acids [show]
Monounsaturated (with one double bond) fatty acids:
- polyunsaturated fatty acids [show]
Polyunsaturated (with two or more double bonds) fatty acids:
In addition to these main three groups, there is also a group of so-called unusual natural fatty acids [show] .
Fatty acids that make up the lipids of animals and higher plants have many common properties. As already noted, almost all natural fatty acids contain an even number of carbon atoms, most often 16 or 18. Unsaturated fatty acids in animals and humans involved in the construction of lipids usually contain a double bond between the 9th and 10th carbons; additional double bonds, such as usually occur in the area between the 10th carbon and the methyl end of the chain. The counting starts from the carboxyl group: the C-atom closest to the COOH group is designated as α, the one next to it is designated as β, and the terminal carbon atom in the hydrocarbon radical is designated as ω.
The peculiarity of the double bonds of natural unsaturated fatty acids is that they are always separated by two simple bonds, that is, there is always at least one methylene group between them (-CH=CH-CH 2 -CH=CH-). Such double bonds are referred to as “isolated.” Natural unsaturated fatty acids have a cis configuration and trans configurations are extremely rare. It is believed that in unsaturated fatty acids with several double bonds, the cis configuration gives the hydrocarbon chain a bent and shortened appearance, which has biological meaning(especially considering that many lipids are part of membranes). In microbial cells, unsaturated fatty acids usually contain one double bond.
Long chain fatty acids are practically insoluble in water. Their sodium and potassium salts (soaps) form micelles in water. In the latter, the negatively charged carboxyl groups of fatty acids face the aqueous phase, and the nonpolar hydrocarbon chains are hidden inside the micellar structure. Such micelles have a total negative charge and remain suspended in solution due to mutual repulsion (Fig. 95).
Neutral fats (or glycerides)
Neutral fats are esters of glycerol and fatty acids. If all three hydroxyl groups of glycerol are esterified with fatty acids, then such a compound is called a triglyceride (triacylglycerol), if two are esterified, a diglyceride (diacylglycerol) and, finally, if one group is esterified, a monoglyceride (monoacylglycerol).
Neutral fats are found in the body either in the form of protoplasmic fat, which is structural component cells, or in the form of spare, reserve fat. The role of these two forms of fat in the body is not the same. Protoplasmic fat has a constant chemical composition and is contained in tissues in a certain amount, which does not change even with morbid obesity, while the amount of reserve fat undergoes large fluctuations.
The bulk of natural neutral fats are triglycerides. The fatty acids in triglycerides can be saturated or unsaturated. The most common fatty acids are palmitic, stearic and oleic acids. If all three acid radicals belong to the same fatty acid, then such triglycerides are called simple (for example, tripalmitin, tristearin, triolein, etc.), but if they belong to different fatty acids, then they are mixed. The names of mixed triglycerides are derived from the fatty acids they contain; in this case, the numbers 1, 2 and 3 indicate the connection of the fatty acid residue with the corresponding alcohol group in the glycerol molecule (for example, 1-oleo-2-palmitostearin).
The fatty acids that make up triglycerides practically determine them physicochemical characteristics. Thus, the melting point of triglycerides increases with increasing number and length of saturated fatty acid residues. In contrast, the higher the content of unsaturated or short-chain fatty acids, the lower the melting point. Animal fats (lard) usually contain a significant amount of saturated fatty acids (palmitic, stearic, etc.), due to which they room temperature hard. Fats, which contain many mono- and polyunsaturated acids, are liquid at ordinary temperatures and are called oils. Thus, in hemp oil, 95% of all fatty acids are oleic, linoleic and linolenic acids, and only 5% are stearic and palmitic acid. Note that human fat, which melts at 15°C (it is liquid at body temperature), contains 70% oleic acid.
Glycerides are capable of entering into all chemical reactions characteristic of esters. Highest value has a saponification reaction, as a result of which glycerol and fatty acids are formed from triglycerides. Saponification of fat can occur either through enzymatic hydrolysis or through the action of acids or alkalis.
Alkaline breakdown of fat under the action of caustic soda or caustic potassium is carried out during the industrial production of soap. Let us remember that soap is sodium or potassium salts of higher fatty acids.
The following indicators are often used to characterize natural fats:
- iodine number - the number of grams of iodine that is in certain conditions binds 100 g of fat; given number characterizes the degree of unsaturation of fatty acids present in fats, the iodine number of beef fat is 32-47, lamb fat 35-46, pork fat 46-66;
- acid number - the number of milligrams of potassium hydroxide required to neutralize 1 g of fat. This number indicates the amount of free fatty acids present in the fat;
- saponification number - the number of milligrams of potassium hydroxide used to neutralize all fatty acids (both those included in triglycerides and free ones) contained in 1 g of fat. This number depends on the relative molecular weight of the fatty acids that make up the fat. The saponification number for the main animal fats (beef, lamb, pork) is almost the same.
Waxes are esters of higher fatty acids and higher monohydric or dihydric alcohols with the number of carbon atoms from 20 to 70. Their general formulas are presented in the diagram, where R, R" and R" are possible radicals.
Waxes can be part of the fat covering the skin, wool, and feathers. In plants, 80% of all lipids that form a film on the surface of leaves and trunks are waxes. Waxes are also known to be normal metabolites of certain microorganisms.
Natural waxes (eg. beeswax, spermaceti, lanolin) usually contain, in addition to the mentioned esters, a certain amount of free higher fatty acids, alcohols and hydrocarbons with a number of carbon atoms of 21-35.
Phospholipids
This class of complex lipids includes glycerophospholipids and sphingolipids.
Glycerophospholipids are derivatives of phosphatidic acid: they contain glycerol, fatty acids, phosphoric acid and usually nitrogen-containing compounds. General formula glycerophospholipids are presented in the diagram, where R 1 and R 2 are radicals of higher fatty acids, and R 3 is a radical of a nitrogenous compound.
A characteristic feature of all glycerophospholipids is that one part of their molecule (radicals R 1 and R 2) exhibits pronounced hydrophobicity, while the other part is hydrophilic due to the negative charge of the phosphoric acid residue and the positive charge of the R 3 radical.
Of all lipids, glycerophospholipids have the most pronounced polar properties. When glycerophospholipids are placed in water, only a small part of them passes into the true solution, while the bulk of the “dissolved” lipid is in water systems in the form of micelles. There are several groups (subclasses) of glycerophospholipids.
- [show]
.
- Phosphatidylserines [show]
.
In the phosphatidylserine molecule, the nitrogenous compound is the amino acid residue serine.
Phosphatidylserines are much less widespread than phosphatidylcholines and phosphatidylethanolamines, and their importance is determined mainly by the fact that they participate in the synthesis of phosphatidylethanolamines.
- Plasmalogens (acetal phosphatides) [show]
.
They differ from the glycerophospholipids discussed above in that instead of one higher fatty acid residue, they contain a fatty acid aldehyde residue, which is linked to the hydroxyl group of glycerol by an unsaturated ester bond:
Thus, plasmalogen, upon hydrolysis, breaks down into glycerol, higher fatty acid aldehyde, fatty acid, phosphoric acid, choline or ethanolamine.
[show]
.
Unlike triglycerides, in the phosphatidylcholine molecule, one of the three hydroxyl groups of glycerol is associated not with fatty acid, but with phosphoric acid. In addition, phosphoric acid, in turn, is connected by an ester bond to the nitrogenous base [HO-CH 2 -CH 2 -N+=(CH 3) 3 ] - choline. Thus, the phosphatidylcholine molecule contains glycerol, higher fatty acids, phosphoric acid and choline
[show] .
The main difference between phosphatidylcholines and phosphatidylethanolamines is that the latter contain the nitrogenous base ethanolamine (HO-CH 2 -CH 2 -NH 3 +) instead of choline.
Of the glycerophospholipids in the body of animals and higher plants, phosphatidylcholines and phosphatidylethanolamines are found in the largest quantities. These two groups of glycerophospholipids are metabolically related to each other and are the main lipid components of cell membranes.
The R3 radical in this group of glycerophospholipids is the six-carbon sugar alcohol - inositol:
Phosphatidylinositols are quite widespread in nature. They are found in animals, plants and microbes. In animals, they are found in the brain, liver and lungs.
[show] . 
It should be noted that free phosphatidic acid occurs in nature, although in relatively small quantities compared to other glycerophospholipids.
Cardiolylin belongs to glycerophospholipids, more precisely to polyglycerol phosphates. The backbone of the cardiolipin molecule includes three glycerol residues connected to each other by two phosphodiester bridges through positions 1 and 3; the hydroxyl groups of the two outer glycerol residues are esterified with fatty acids. Cardiolipin is part of mitochondrial membranes. In table 29 summarizes data on the structure of the main glycerophospholipids.
Among the fatty acids that make up glycerophospholipids, both saturated and unsaturated fatty acids are found (usually stearic, palmitic, oleic and linoleic).
It has also been established that most phosphatidylcholines and phosphatidylethanolamines contain one saturated higher fatty acid, esterified in position 1 (at the 1st carbon atom of glycerol), and one unsaturated higher fatty acid, esterified in position 2. Hydrolysis of phosphatidylcholines and phosphatidylethanolamines with the participation of special enzymes contained , for example, in cobra venom, which belong to phospholipases A 2, leads to the cleavage of unsaturated fatty acids and the formation of lysophosphatidylcholines or lysophosphatidylethanolamines, which have a strong hemolytic effect.
Sphingolipids
Glycolipids
Complex lipids containing carbohydrate groups in the molecule (usually a D-galactose residue). Glycolipids play an essential role in the functioning of biological membranes. They are found primarily in brain tissue, but are also found in blood cells and other tissues. There are three main groups of glycolipids:
- cerebrosides
- sulfatides
- gangliosides
Cerebrosides contain neither phosphoric acid nor choline. They contain a hexose (usually D-galactose), which is linked by an ester bond to the hydroxyl group of the amino alcohol sphingosine. In addition, Cerebroside contains a fatty acid. Among these fatty acids, the most common are lignoceric, nervonic and cerebronic acids, i.e. fatty acids having 24 carbon atoms. The structure of cerebrosides can be represented by a diagram. Cerebrosides can also be classified as sphingolipids, since they contain the alcohol sphingosine.
The most studied representatives of cerebrosides are nervon, containing nervonic acid, cerebron, which includes cerebronic acid, and kerazin, containing lignocyric acid. The content of cerebrosides in membranes is especially high nerve cells(in the myelin sheath).
Sulfatides differ from cerebrosides in that they contain a sulfuric acid residue in the molecule. In other words, the sulfatide is a cerebroside sulfate in which the sulfate is esterified at the third carbon atom of the hexose. In the mammalian brain, sulfatides, like n cerebrosides, are found in the white matter. However, their content in the brain is much lower than that of cerebrosides.
When hydrolyzing gangliosides, one can detect higher fatty acid, sphingosine alcohol, D-glucose and D-galactose, as well as amino sugar derivatives: N-acetylglucosamine and N-acetylneuraminic acid. The latter is synthesized in the body from glucosamine.
Structurally, gangliosides are largely similar to cerebrosides, the only difference being that instead of a single galactose residue they contain a complex oligosaccharide. One of the simplest gangliosides is hematoside, isolated from the stroma of erythrocytes (scheme)
Unlike cerebrosides and sulfatides, gangliosides are found predominantly in the gray matter of the brain and are concentrated in the plasma membranes of nerve and glial cells.
All the lipids discussed above are usually called saponified, since their hydrolysis produces soaps. However, there are lipids that do not hydrolyze to release fatty acids. These lipids include steroids.
Steroids are compounds widespread in nature. They are derivatives of a core containing three fused cyclohexane rings and one cyclopentane ring. Steroids include numerous substances of a hormonal nature, as well as cholesterol, bile acids and other connections.
In the human body, the first place among steroids is occupied by sterols. The most important representative of sterols is cholesterol:
It contains an alcohol hydroxyl group at C3 and a branched aliphatic chain of eight carbon atoms at C17. The hydroxyl group at C 3 can be esterified with higher fatty acid; in this case, cholesterol esters (cholesterides) are formed:
Cholesterol plays a role as a key intermediate in the synthesis of many other compounds. The plasma membranes of many animal cells are rich in cholesterol; it is found in significantly less quantity in mitochondrial membranes and in the endoplasmic reticulum. Note that there is no cholesterol in plants. Plants have other sterols, collectively known as phytosterols.
07.04.2009
Fats make up approximately 44 percent of the diet. Recommendations on a proper diet advise that this figure should not exceed 30 percent of total calories, and 25 percent would be even better.
Your fat intake should lean towards polyunsaturated and monounsaturated fats with maximum number saturated fat no more than 10 percent or less of that total 25 percent fat.
* To reduce the fat content when preparing an omelet, remove the yolk of every second egg, this will reduce fat and cholesterol levels, and you will not even feel the difference.
*Cottonseed oil is 25 percent saturated fat and is not the best to use.
* Soybean oil changes taste when long-term storage, due to changes in the levels of linolenic acid it contains.
* Sixty-four percent of the calories from caviar come from fat.
*Butter absorbs refrigerator odors, so it should be stored in a closed container.
* Butter can be stored in the refrigerator for only two weeks. If you need to preserve it for a longer period, store it in the freezer.
*Eight ounces of potato chips equals consuming 12 to 20 teaspoons of fat.
*Try using water instead of fat in some recipes. It is true that fats make dressings, etc., the taste becomes smooth, but if you mix water with flour, with corn starch (corn meal) or potato starch, it will save you from extra calories.
* Oils should be stored in dark containers and stored in a dark, cool place to reduce the risk of rancidity.
* When carob is made into candy, fat is added for texture, making the fat level close to that of real chocolate. In fact, the cocoa butter used in chocolate production is 60 percent saturated fat, while the fat in carob candies is, in most cases, 85 percent saturated fat.
* Using non-stick cookware and sprays vegetable oils will reduce fat consumption.
* Never eat mayonnaise-based salad dressing or salad unless you are sure it has been refrigerated until you are ready to eat it. Neglecting this is responsible for thousands of cases of food poisoning every year.
* Fish-related oils are more beneficial than meat-related oils. Fish contains a high percentage of omega fatty acids.
* Any margarine containing coconut or Palm oil will have very high levels of saturated fat. Labels now call them tropical oils (tropical plant oils).
* New fat substitutes continue to appear in our products. Don't forget that they are still synthetic and not a natural product. They should not be seen as a panacea for replacing fat in our diet.
* The best butter is made from AA sweet cream.
*An ounce of sunflower seeds contains 160 calories and is not considered a dietary snack.
* A burrito topped with sour cream and guacamole (a sauce made from mashed avacado, tomatoes, spices and mayonnaise) can contain up to 1,000 calories and 59 percent fat.
* Research has shown that stearic acid, a saturated fat, has little effect on raising cholesterol levels.
*The new reduced-fat peanut butter has the same number of calories per serving as regular peanut butter, approximately 190 calories per serving, and has been added with sweeteners instead of fat.
* When you store some oils in the refrigerator, they may become cloudy (not clear, light cloudy), this is due to the formation of harmless crystals. Manufacturers sometimes refrigerate oils before releasing them for sale and remove these crystals in a process called “winterizing.” Now these oils will remain clear when cooled.
* Pork fat has large crystals, whereas butter small size. This is highly dependent on the texture of the fat and can be controlled during processing. The size of the crystals can be changed by shaking (shaking) the oil while it cools.
* Studies have shown that people on a diet miss fat more than sweets.
* People on a diet with high content fats are more prone to colon cancer, prostate cancer or breast cancer. Future research may show that this also has an effect harmful effect on the immune system.
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