Alimentary fiber. Dietary fiber in foods and diet, benefits and harms

Each of us once heard that coarse dietary fibers are extremely useful for our body. In what products they are contained and what significance they have for human health - this information is laid out below. In addition, the article describes the benefits of the above substances for losing weight people.

What is coarse dietary fiber

Entering human body in the form of undigested carbohydrates with plant foods. These are polymers of polysaccharides and their derivatives.

These substances are divided into two large groups:

soft soluble;
coarse insoluble.

Soft dietary fibers include dextrans, agarose, gum, pectins. Coarse fiber is fiber, which is a glucose polymer. Due to some differences in the chain of molecules, it does not break down in the digestive tract.

It should be noted that coarse fibers are not sources of energy. Under the action of microorganisms, they are partially broken down. However, the energy released during this process, is fully used for the needs of bacteria.

Monosaccharides, which are formed during the decomposition of food fibers, are converted into volatile fatty acids: butyric, propionic and acetic. These substances are partially absorbed through the intestinal walls, and only 1% of them enter the human body. Lignin, which contains a lot of foods with coarse dietary fiber, is not absorbed at all. Therefore, very often they are characterized as "ballast substances". But in vain! 'Cause they're playing essential role in the process of digestion.

Coarse dietary fiber: composition

Fiber is made up of glucose molecules. It is often found in nature and is similar to starch. It is known that any plants and trees also consist of cellulose, which, of course, does not split. The same happens in the human body: the stomach cannot extract it, so it does not carry any energy in itself.

This fact contributed to the fact that many scientists of the last century began to prove that the coarse fiber in the products is "ballast" and does not benefit the body. The researchers wanted to "purify" the food of the above substances. As a result, people's health has deteriorated significantly. believe that the decrease in dietary fiber in food in the middle of the 20th century caused the development of many oncological diseases, obesity, heart problems, bowel disease.

The role of fiber in the body

The functions of dietary coarse fibers are quite diverse:

accelerate the synthesis of lipase in adipose tissue;
reduce the rate of absorption of di- and monosaccharides in the intestine;
regulate blood glucose levels;
protect the body from increased;
increase the excretion and binding of bile acids, cholesterol and neutral steroids;
contribute to maintaining body weight in ideal terms;
lower the synthesis of cholesterol and fatty acids in the liver;
control the level of phospholipids in bile;
prevent stone formation in the gallbladder;
provide normal peristalsis of the biliary tract and intestines;
prevent the development of hemorrhoids and constipation.

In addition, fiber has the ability to absorb salts of heavy metals, thereby preventing their absorption into the organs.

Coarse dietary fiber is extremely useful for women's health. Scientists have proven that women who consume enough foods with coarse dietary fiber have a reduced risk of developing ovarian and breast cancer.

Soft and coarse fibers: what products contain

Both soluble and insoluble must be present in the human diet. Indeed, to ensure the normal functioning of the body, we need soft and coarse fibers. What products contain them? This information will be displayed in the following list:

1. Soluble dietary fiber:

cereals (barley, rye, oats);
legumes (beans, lentils, peas, beans);
fruits (prunes, avocados, apple peel, raisins, quince and peach peel).

2. Products containing coarse dietary fiber insoluble:

bran;
cauliflower;
broccoli;
string beans;
fruit peel;
legumes;
nuts, seeds;
buckwheat;
potatoes in "uniforms";
mushrooms.

A small amount of fiber is present in the composition of vegetables such as carrots, pumpkin, onions, parsley, tomato, beets, cucumber, Bell pepper, spinach, dill, zucchini.

It should be noted that heat treatment does not affect the amount of fiber in vegetables at all.

Interestingly, there is food that contains both soft and coarse fibers. What foods contain both types of food above substances? It's primarily beans. Also, soft and coarse dietary fiber is found in the peel of many fruits.

Brief description of products containing coarse dietary fiber

Bran. This product contains about 40% fiber. All bran - and rye, and soy, and oats, and wheat - are an excellent source of coarse fibers.
Buckwheat. This product contains 2 times more fiber than other cereals. If a person eats one glass of buckwheat, he will provide himself with 20% daily allowance coarse food fibers.
Seeds. An excellent source of fiber is flaxseed. A tablespoon of this product contains about 7 g of fiber.

Daily requirement for coarse fibers

A healthy person daily needs about 25-40 g of the above substances to enter his body with food. The daily requirement for each individual is different. It depends on the calorie content of the diet physical activity person, their state of health and weight, as well as other factors.

For children, in comparison with an adult organism, the daily requirement for dietary coarse fibers is slightly lower.

Scientists say: in order to provide the body with these substances in the above amount, ordinary person about 1.5 kg of fresh fruits and vegetables should be eaten per day. Of course, in most cases this number is unbearable. Therefore, experts advise diversifying the diet with other products that contain coarse dietary fiber.

An interesting fact: scientists have studied that a person eats no more than 25 g of the above substances per day, of which 10 g is found in bread and other cereal products, 7 g is in potatoes, 6 g is in other vegetables, 2 g is in fruits .

Fibers are coarse when losing weight

Products containing coarse fiber are extremely beneficial for obese people. If enough fiber enters the human body, then this contributes to the following processes:

the rate of gastric emptying is significantly reduced;
its stretching increases, which helps to create a feeling of fullness and prevents overeating;
appetite is suppressed.

In addition, coarse dietary fiber reduces in adipose tissue. They also have a diuretic effect. This means that fiber helps to remove sodium and water from the body.

Contraindications to the use of coarse dietary fiber

The above substances in some diseases should be used with caution and in moderation. It:

inflammation of the esophagus;
stomach ulcer;
gastritis;
duodenitis.

Experts note that when there is an exacerbation of these diseases, it is generally undesirable to use foods with coarse dietary fiber. Doctors recommend that such people make a special diet, where the above products are present in a minimal amount.

Coarse dietary fibers are not a source of energy, but provide a number of vital processes in the human body, including the acceleration of the passage of food contents through the digestive tract. Deficiency of these substances can lead to serious problems with health, so you need to include them in your diet.

We answer the main questions: what, why and how

Without them, the full functioning of the digestive system is impossible. They help the body cleanse itself. It also boosts immunity and promotes weight loss. Alimentary fiber useful to a lot of people!

We tell you more about these food components and answer the main questions about them.

What is dietary fiber?

This substance plant origin, which are part of fruits, vegetables, cereals and other plants. It does not contain anything useful - vitamins, minerals, protein and other nutrients. Moreover, dietary fiber (they are also fiber) is not even digested and absorbed by the body! Despite this, they are so important that nutritionists put them on a par with proteins, fats and carbohydrates.

Why does the body need dietary fiber?

Fiber performs a number of useful functions.

It is necessary for proper bowel function. Passing through it, fiber “absorbs” and removes toxins - thereby helping the body process and absorb food.
Cellulose- a kind of "food" for intestinal bacteria. When there is not enough fiber, they “starve” and cannot fully synthesize vitamins, amino acids, hormones, micro and macro elements, and much more.
improve intestinal microflora. Hence the improvement of immunity, because it is in the intestines - 80% immune cells organism! Given this, in the cold season, you need to especially lean on vegetables, fruits and grains.
help control appetite and more effective weight loss. Even a small portion of dietary fiber relieves hunger for a long time - which means that it becomes much easier to avoid overeating!
Cellulose lowers blood sugar and cholesterol levels. Development risk cardiovascular disease and diabetes is reduced at times!

What are dietary fibers?

There are two types of dietary fiber: soluble and insoluble.

Soluble, getting into the body, absorb water and increase in volume, turning into a thick and sticky substance. Such a process can be observed, for example, when preparing oatmeal. Swelling, soluble fibers fill the stomach and provide a feeling of satiety. AT in large numbers soluble fibers are found in apples, oranges, carrots, potatoes, oats, barley and beans.

insoluble fiber goes through digestive tract, absorbing less water and therefore almost not changing in volume. It stimulates the intestines, accelerating the elimination of undigested food debris and toxins. Rich in insoluble fiber bran and other types of whole grain, vegetables.

How much dietary fiber do you need per day?

The daily intake of fiber is 25-30 g. However, in a normal diet modern man there is a maximum of 12-15 g of fiber per day, which does not cover even half of the norm!

How to increase your intake of dietary fiber?

Increase your fiber intake gradually over several weeks. Sudden changes will cause discomfort.

Here are some tips on how to add more fiber to your diet:

Eat the fruit with the skin on. If you are preparing a drink from them, it is better to make a smoothie (then the product is crushed completely, with the skin) than juice.
Add vegetables to each of your main meals: breakfast, lunch, and dinner.
There is not a gram of fiber in white flour - it remains in the outer layers of the grains, from which they are cleaned during processing. Therefore, it is necessary to exclude the usual pastries from the diet as much as possible, and instead use whole wheat bread, muesli and bread.
Swap polished white rice for brown or black rice, barley, millet, beans, lentils and other unrefined grains.
A record concentration of fiber is found in bran, which is easy to add to any drinks.
You can also supplement your diet with specialized sources of fiber – for example, start the day with Herbalife Apple Oatmeal Drink, which provides 5 g of quality fiber in one serving, or Herbalife Dietary Fiber Complex, which provides 150% of the recommended intake of soluble dietary fiber.

So, cellulose- the most valuable substance in our diet. Adequate fiber intake will help maintain a healthy digestive system, strengthen immunity and make it easier to achieve your goals. better shape!

December 9, 2015, 18:18 2015-12-09

THE SIGNIFICANCE OF DIETARY FIBER IN THE NUTRITION

To maintain human health you need to feed not only yourself, but also inhabiting the gastrointestinal tract microorganisms.

1. GENERAL INFORMATION ABOUT DIETARY FIBER

According to Guidelines MP 2.3.1.2432-08(Norms of physiological needs for energy and nutrients for various population groups Russian Federation) in the dietary fiber group includes polysaccharides, mainly vegetable, whichto a small extentdigested in the large intestine and have a significant effect onmicrobiocinosis,as well asprocesses of digestion, assimilation and evacuation of food.

Physiological need in dietary fiber for an adult is 20 g / day, for children over 3 years old 10-20 g / day.

As is known, is a large heterogeneous group of polysaccharides that refers to , and this is the very component of food that is currently being talked about so much and which, without noticing it, is daily excluded from the diet.It should be recalled that prebiotics are carbohydrates that are not broken down in the upper gastrointestinal tract (and other foods), and which are a source of nutrition for normal microflora intestines. According to resistance to bacterial fermentation, dietary fibers are divided into fully fermentable, partially fermentable and non-fermentable. The first group includes pectin, gums and mucus, the second - cellulose and hemicellulose, the third group is lignin. Vegetables and fruits are the main sources of the first group of dietary fiber.

The biological effect of dietary fiber on human health is truly unique.

So, they retain water, preventing the formation of fecal stones, thereby affecting the osmotic pressure in the gastrointestinal tract, the electrolyte composition of the intestinal contents and the mass of feces, increasing their volume and weight, ultimately stimulating the motility of the gastrointestinal tract.

Dietary fiber adsorbs bile acids, regulating their distribution in the intestines and reabsorption, which is directly related to the level of steroid losses in the faeces and cholesterol metabolism and the regulation of both bile acids and steroid hormones and cholesterol metabolism. These compounds normalize the habitat of intestinal bacteria, favoring the growth of primarily vital lacto-and. About 50% of dietary fiber from food is used by the microflora of the colon.

Due to the normalization of the gastrointestinal tract, dietary fiber prevents the occurrence and development of cancer of the colon and other parts of the intestine. High absorption properties and antioxidant activity contribute to the removal of endo- and exotoxins from the body. Dietary fiber forms gel-like structures, speeding up gastric emptying and the speed of food passing through gastrointestinal tract. Finally, dietary fiber prevents the occurrence and development of atherosclerosis, hypertension and diabetes.

The predominant localization of dietary fibers in the shell of seeds, peel of fruits and root crops is determined by protective functions that ensure the safety of the fruit and create optimal conditions for grain germination. When it comes to the role of dietary fiber in human health, then, first of all, they remember their ability to protect the body from rectal cancer. For the first time, Burkitt drew attention to this relationship, noting amazing fact extremely low incidence of rectal cancer in the population of most countries in Africa, where the diet is rich in dietary fiber and vitamins. There are other equally impressive facts.

In Los Angeles, non-drinking, non-smoking dairy vegetarians have a 70% lower incidence of colorectal cancer than whites living in similar environmental conditions. The number of cases of colorectal cancer is increasing sharply among Poles and Hungarians, Puerto Ricans and Japanese who came to live in the United States and changed the national diet rich in dietary fiber to the Western one, characterized by a high degree of food purification (from dietary fiber) and a relatively high consumption of fat.

In an effort to cleanse food from unsightly dietary fiber, a person received snow-white flour, light rice, tender stewed vegetables, and sugar. The consequences, as we see, were catastrophic. Here is a typical example. First world war the crew of the fastest German warship-raider successfully piracy in the waters of the Atlantic Ocean. They were strong, young, well-trained sailors of the German fleet. Capturing ships, they took the most valuable refined products (sugar, flour) at that time. As a result, after 8 months of such a life, half of the team fell ill, unable to fulfill their duties. As a result, the raider entered the neutral waters of New York and surrendered.

In nature, the regulation of the processes of splitting and absorption of carbohydrates, the removal of toxic substances from the body is carried out through food fiber, or dietary fiber. With a lack of the latter, conditions are created for the accumulation of sugar in the blood (the development of diabetes), an increase in blood pressure, the accumulation of toxic substances, and the development of rectal cancer.

A large role in the occurrence of rectal cancer is played by high fat intake, which increases the synthesis of cholesterol and bile acids by the liver. In the intestines, they are converted into secondary bile acids, cholesterol derivatives, and other potentially toxic compounds. It is known that these compounds destroy the rectal mucosa, affect the viscosity of cell membranes and the metabolism of prostaglandins. Dietary fiber, not absorbed by the body, contributes to intestinal peristalsis, eliminating congestion and associated toxicosis.

In general, the anticarcinogenic effect of dietary fiber is associated with:

an increase in stool volume (decrease in the residence time of decay products in the intestine, that is, less contact time with carcinogens; dilution of carcinogens)
adsorption (absorption) of bile acids and other potential carcinogens
a decrease in the acidity of feces, which helps to slow down the process of bacterial destruction of food components to carcinogens and deactivation of bile acids
a decrease in the amount of secondary bile acids
enzymatic breakdown of fats into short chain compounds

Modern society is passionate about the saving properties of dietary fiber.

The corresponding dietary supplements are made from grain husks (the most common example is wheat bran), all kinds of cakes (sugar beet, sunflower, amaranth, stakhis), alfalfa, psyllium seeds, and even pine sawdust. And at the same time, they throw away the peel of vegetables and fruits, use highly refined grains in food, rarely including vegetable dishes in the diet. It ignores Commoner's most important environmental law, "Nature knows best," which suggests that plant foods high in dietary fiber are optimal for human health.

The role of dietary fiber in nutrition modern man is especially great due to the fact that we live in an era of global environmental crisis, when, in addition to natural toxic substances formed during the digestion of food (metabolites of cholesterol and bile acids), a huge amount of toxicants enters the body from the outside with food, inhaled air, water. These are pesticides, and heavy metals, and radionuclides. For the removal of such substances from the body, dietary fiber is indispensable. Meanwhile, with a consumption rate of 20-35 g per day, Europeans receive no more than 15 g of dietary fiber with food.

Lack of PV in the diet can lead to a number of pathological conditions, many of which are somehow associated with a violation of the composition of the intestinal microflora. PV deficiency is associated with the development of a number of diseases and conditions, such as colon cancer, irritable bowel syndrome, constipation, cholelithiasis, diabetes, obesity, atherosclerosis, ischemic heart disease, varicose veins and thrombosis of the veins of the lower extremities, etc.

The most important sources of dietary fiber for humans among vegetable crops are legumes, spinach, cabbage.

Studies of the addition of vegetables and fruits to the diet have shown that this dietary modification itself leads to a decrease in the consumption of fats and refined carbohydrates. These data confirm the assumption that the solution to the problem overweight by consuming more vegetables and fruits is a preferred approach than by restricting diet.

vegetable crops are widely used to obtain functional foods with prebiotic properties. It is well known that the intestinal microflora largely determines human health. Prebiotics, such as dietary fiber, oligosaccharides and inulin, are food components that are not degraded in the gastrointestinal tract and provide selective stimulation of growth and activity. beneficial bacteria intestines, such as bifidus and lactobacilli.

The action of prebiotics on human health, therefore, is not direct, but indirectly through the restoration of the intestinal microflora (especially the rectum). Indeed, bifidobacteria stimulate immune system, contribute synthesis of vitamins group B, inhibit growth pathogenic microorganisms lower blood cholesterol levels, restore intestinal microflora after antibiotic therapy. Lactobacilli promote the absorption of lactose in lactose intolerance, prevent constipation and diarrhea, and increase resistance to infections such as salmonellosis. It has been established that the use of prebiotics to increase the content of bifidus and lactobacilli in the intestine is an effective method against ulcerative colitis. A wide range of action of bifidobacteria and lactobacilli determines the success of prebiotics in the treatment of not only the gastrointestinal tract, but in increasing the immunity of the mucous membranes, including the skin and respiratory tract, reducing the risk of cardiovascular diseases and obesity, urogenital infections caused by pathogenic microorganisms by stimulating the growth of lactobacilli. The addition of prebiotics to food improves the organoleptic characteristics of food.

Functional oligosaccharides form an intermediate group between simple sugars and polysaccharides and are dietary fibers and prebiotics. The prebiotic properties of such oligosaccharides (fructooligosaccharides, glucooligosaccharides, isomaltoolygosaccharides, soy oligosaccharides, xylooligosaccharides and maltitol) have been studied the most.

These connections

do not stimulate an increase in blood glucose concentration and insulin secretion;
are low-calorie food components (about 0-3 kcal/g of substrate);
non-carcinogenic;
improve the intestinal microflora, reducing the number of pathogenic bacteria and providing nutrition for bifidus and lactobacilli;
prevent the development of diarrhea and constipation;
improve the absorption of calcium, magnesium, iron and other elements in the intestine.

Obesity and type 2 diabetes are typical diseases of modern Western society. Dietary recommendations for these diseases include increased intake of dietary fiber that controls glucose release (Bennett et al., 2006). Dietary fibers bind bile acids and prevent their reabsorption in the liver, thus inhibiting cholesterol synthesis. Some authors also note that functional oligosaccharides improve the absorption of water and electrolytes in the small intestine, which reduces the incidence of diarrhea and reduces the duration of treatment.

Functional oligosaccharides prevent tumor development in humans (Chen & Fukuda, 2006). Possible Mechanisms their actions in these cases include reducing the chemical absorption of carcinogens by speeding up bowel movements, improving bacterial nutrition, and increasing the production volatile fatty acids, lowering the pH of feces, which contributes to the excretion of carcinogens. Oligosaccharides improve the absorption of zinc, copper, selenium, magnesium and iron, which is extremely important, for example, in osteoporosis, when there is an increase in calcium leaching from the body. Dietary fiber balances calcium intake with diet and fiber type.

Recent studies show that functional oligosaccharides exhibit, antimutagenic , antibacterial properties.

2. FIBER IN A BRIEF

Cell wall components are waste products of the cell. They are released from the cytoplasm and undergo transformations on the surface of the plasmalemma. Primary cell walls contain based on dry matter: 25% cellulose, 25% hemicellulose, 35% pectin and 1-8% structural proteins. However, the numbers fluctuate a lot. Thus, the composition of the cell walls of cereal coleoptiles includes up to 60-70% hemicellulose, 20-25% cellulose, 10% pectin. At the same time, the cell walls of the endosperm contain up to 85% hemicelluloses. There is more cellulose in the secondary cell walls. The skeleton of the cell membrane is made up of intertwined micro- and macrofibrils of cellulose.

Cellulose, or fiber (C 6 H 10 O 5) n, is a long unbranched chain consisting of 3-10 thousand D-glucose residues connected b-1,4-glycosidic bonds. Cellulose molecules are combined into a micelle, micelles are combined into a microfibril, microfibrils are combined into a macrofibril. Macrofibrils, micelles and microfibrils are connected into bundles by hydrogen bonds. The structure of micro- and macrofibrils is heterogeneous. Along with well-organized crystalline areas, there are paracrystalline and amorphous ones.

Micro- and macrofibrils of cellulose in the cell membrane are immersed in an amorphous jelly-like mass - the matrix. The matrix consists of hemicelluloses, pectins and protein. Hemicelluloses, or semi-celluloses, are derivatives of pentoses and hexoses. Of the hemicelluloses, the most important are xyloglucans, which are part of the matrix of the primary cell wall. These are chains of D-glucose residues connected b-1,4-glycosidic bonds, in which side chains extend from the sixth carbon atom of glucose, mainly from D-xylose residues. Residues of galactose and fucose can be attached to xylose. Hemicelluloses are able to bind to cellulose, so they form a shell around cellulose microfibrils, fastening them into a complex chain.

More about dietary fiber:

3. Classification of indigestible carbohydrates (dietary fiber)

Alimentary fiber(indigestible indigestible carbohydrates, fiber, ballast substances) - are substances of various chemical nature (all of them are polymers of monosaccharides and their derivatives) that do not break down into small intestine, but undergo bacterial fermentation in the large intestine.

Dietary fiber enters the human body with plant foods.

The names "fiber" or "dietary fiber" are commonly used, but to a certain extent they are erroneous, since the material denoted by this word does not always have a fibrous structure, and some types of indigestible carbohydrates (pectins and resins) may well dissolve in water. The most correct name for this group of substances is indigestible carbohydrates, however, in the literature, the term "dietary fiber - PV" is most often used.

There are six major types of PV (scheme 1). Chemical analysis showed that these are mainly polysaccharides. But from these positions, the definition of fibers will be insufficient, because other polysaccharides, such as starch, are also present in the diet. It is most accurate to refer to most fiber fractions as non-starch polysaccharides. They can be further divided into cellulose and non-cellulose polysaccharides. The latter include hemicelluloses, pectin, storage polysaccharides like inulin and guar, as well as vegetable gums and mucus. Finally, non-cellulose polysaccharides can be divided into water-soluble and water-insoluble components. Lignin is not a carbohydrate and should be treated as a separate fiber.

Scheme 1. The main types of dietary fiber

According to their physicochemical properties, indigestible carbohydrates are divided into 2 types: soluble in water (they are also called "soft" fibers), and insoluble (they are often called "coarse" fibers).

Soluble dietary fiber absorbs water and forms a gel, lowers cholesterol and blood sugar levels. These "soft" fibers include pectins, gums, dextrans, mucus, and some fractions of hemicellulose.

Insoluble Dietary fibers pass through the gastrointestinal tract almost unchanged, adsorb large amounts of water, and affect intestinal motility. These "coarse" fibers include cellulose, lignin and part of the hemicellulose.

Food components related to dietary fiber:

Cellulose. Cellulose is an unbranched polymer of glucose containing up to 10,000 monomers. Different types of cellulose have different properties and different solubility in water.

Cellulose is widely distributed in plant tissues. It is part of the cell walls and perform a supporting function. Cellulose, like starch and glycogen, is a polymer of glucose. However, due to differences in the spatial arrangement of the oxygen "bridge" connecting glucose residues, starch is easily broken down in the intestine, while cellulose is not attacked by the pancreatic enzyme amylase. Cellulose is one of the most abundant compounds in nature. It accounts for up to 50% of the carbon of all organic compounds in the biosphere.

Fitin. Dietary fiber also includes phytic acid, a substance similar in structure to cellulose. Phytin is found in plant seeds.

Chitin. Chitin is a polysaccharide with a structure similar to cellulose. The cell walls of fungi and the shells of crayfish, crabs and other arthropods are composed of chitin.

Hemicellulose. Hemicellulose is formed by the condensation of pentose and hexose residues, which are associated with residues of arabinose, glucuronic acid and its methyl ester. Various types of hemicelluloses include various pentoses (xylose, arabinose, etc.) and hexoses (fructose, galactose, etc.). Just like cellulose different types hemicelluloses have different physicochemical properties.

Hemicelluloses are cell membrane polysaccharides, a very extensive and diverse class of vegetable carbohydrates. Hemicellulose is able to retain water and bind cations. Hemicellulose predominates in grain products, and it is low in most vegetables and fruits.

Lignin. Lignin is a polymeric residue of wood after its percolation hydrolysis, which is carried out in order to isolate cellulose and hemicellulose.

Lignins are a group of carbohydrate-free cell membrane substances. Lignins are made up of polymers of aromatic alcohols. Lignins impart structural rigidity to the shell plant cell, they envelop cellulose and hemicellulose, are able to inhibit the digestion of the shell by intestinal microorganisms, so the products most saturated with lignin (for example, bran) are poorly digested in the intestine.

Pectin. Pectins are a complex complex of colloidal polysaccharides. Pectin is a polygalacturonic acid in which some of the carboxyl groups are esterified with methyl alcohol residues.

Pectins are substances capable of forming jelly in the presence of organic acids and sugar. This property is widely used in the confectionery industry. Pectins are part of the cellular tissue skeleton of fruits and green parts of plants. The sorbing properties of pectins are important - the ability to bind and remove cholesterol, radionuclides, heavy metals (lead, mercury, strontium, cadmium, etc.) and carcinogens from the body. Pectin substances are found in noticeable quantities in products from which jelly can be cooked. These are plums, black currants, apples and other fruits. They contain about 1% pectin. The same amount of pectin is present in beets.

Protopectins. Protopectins are pectin substances, a group of macromolecular compounds that are part of the cell walls and interstitial substance of higher plants. Protopectins are special insoluble complexes of pectin with cellulose, hemicellulose, and metal ions. During the ripening of fruits and vegetables, as well as during their heat treatment, these complexes are destroyed with the release of free pectin from protopectin, which is the reason for the softening of the fruit.

Gum (gum). Gummi (gums) are branched polymers of glucuronic and galacturonic acids, to which residues of arabinose, mannose, xylose, as well as magnesium and calcium salts are attached.

Gums are complex unstructured polysaccharides that are not part of the cell membrane, soluble in water, with viscosity; they are able to bind heavy metals and cholesterol in the intestine.

Slime. Slimes are branched sulfated arabinoxylans.

Slimes, like pectin and gums, are complex mixtures of heteropolysaccharides. Mucus is widely represented in plants. They are used in the same cases as pectins and gums. In food products, the largest amount of mucus is found in oatmeal and pearl barley and rice. There are a lot of mucus in the seeds of flax and plantain.

Alginates. Alginates are salts of alginic acids, found in large quantities in brown algae, the molecule of which is represented by a polymer of polyuronic acids.

4. The biological role of indigestible carbohydrates (dietary fiber) and their metabolism

4.1. Metabolism of dietary fiber

According to the theory balanced nutrition in the gastrointestinal tract, nutrients are separated into nutrients and ballast. Useful substances are broken down and absorbed, and ballast substances are ejected from the body. However, apparently, in the course of natural evolution, nutrition has been formed in such a way that not only utilizable, but also non-utilizable food components become useful. In particular, this applies to non-disposable ballast substances such as dietary fiber.

Dietary fiber is not a source of energy. In humans, they can only be partially broken down in the large intestine by the action of microorganisms. So cellulose is split by 30-40%, hemicellulose - by 60-84%, pectin substances - by 35%. Almost all of the energy released during this process is used by intestinal bacteria for their own needs. Most of the monosaccharides formed during the decomposition of dietary fiber are converted into volatile fatty acids(propionic, oily and acetic) and gases necessary for the regulation of colon function (hydrogen, methane, etc.).

Scheme 2. Consequences of PV metabolism in the large intestine (Weinshtein S.G., 1994)

These substances can be partially absorbed through the intestinal walls, but only about 1% of the nutrients formed during the breakdown of dietary fiber enter the human body. In energy metabolism, this share is negligible, and usually this energy is neglected when studying energy consumption and calorie content of diets. Lignin, which is quite abundant in the cell membranes of plant products, is not completely broken down and absorbed by the human body.

4.2. Functions of dietary fiber in the human body

Dietary fibers differ in composition and in their properties. Different types of PV perform different functions:

Soluble fibers better remove heavy metals, toxic substances, radioisotopes, cholesterol.

Insoluble fiber retains water better, helping to form a soft elastic mass in the intestines and improve its excretion.

Cellulose absorbs water, helps to remove toxins from the body and regulates glucose levels.

Lignin helps remove cholesterol and bile acids found in the gastrointestinal tract.

Gum and gum arabic dissolve in water, creating a feeling of satiety.

Pectin prevents excess cholesterol and bile acids from entering the bloodstream.

4.3. Biological properties of dietary fiber

PV begin to act even in the mouth: while we chew food rich in fiber, salivation is stimulated, which contributes to the digestion of food. We are forced to chew food with fiber for a long time, and the formed habit of chewing food thoroughly improves the functioning of the stomach and cleans the teeth.

Vegetable fibers play a primary role in the formation of feces. This circumstance, as well as the pronounced irritating effect of cell membranes on the mechanoreceptors of the intestinal mucosa, determine their leading role in stimulating intestinal motility and regulating its motor function.

Ballast substances hold water 5-30 times their own weight. Hemicellulose, cellulose and lignin absorb water by filling empty spaces in their fibrous structure. In unstructured ballast substances (pectin, etc.), water binding occurs by turning into gels. Thus, due to an increase in the mass of feces and a direct irritant effect on the large intestine, the speed of intestinal transit and peristalsis increases, which contributes to the normalization of the stool.

PV reduces the time that food spends in the gastrointestinal tract. long delay fecal masses in the colon causes the accumulation and absorption of carcinogenic compounds, which increases the likelihood of developing tumors not only in the intestinal tract, but also in other organs.

Deficiency of dietary fiber in human nutrition leads to a slowdown in intestinal motility, the development of stasis and dyskinesia; is one of the reasons for the increase intestinal obstruction, appendicitis, hemorrhoids, intestinal polyposis, as well as its cancer lower divisions. There is evidence that the lack of dietary fiber in the diet can provoke colon cancer, and the incidence of colon cancer and dysbacteriosis correlates with the provision of dietary fiber diets.

Dietary fibers have a normalizing effect on the motor function of the biliary tract, stimulating the processes of bile excretion and preventing the development of congestion in the hepatobiliary system. As a result, patients with liver disease and biliary tract must be taken with food increased quantities cell membranes.

Enrichment of the diet with ballast substances reduces the lithogenicity of bile, normalizing the cholate-cholesterol coefficient and lithogenic index by adsorbing cholic acid and inhibiting its microbial transformation into deoxycholic acid, alkalizes bile, enhances the kinetics of the gallbladder, which is especially useful preventive measure in individuals at risk of developing cholelithiasis.

Dietary fiber increases the binding and excretion of bile acids, neutral steroids, including cholesterol, and reduces the absorption of cholesterol and fats in the small intestine. They reduce the synthesis of cholesterol, lipoproteins and fatty acids in the liver, accelerate the synthesis of lipase in adipose tissue, an enzyme that breaks down fat, that is, they have a positive effect on fat metabolism. Fiber helps reduce cholesterol levels, and with it the risk of atherosclerosis. Especially pronounced effect on cholesterol metabolism in pectins, in particular, apple and citrus.

Ballast substances slow down the access of digestive enzymes to carbohydrates. Carbohydrates begin to be absorbed only after the intestinal microorganisms partially destroy the cell membranes. Due to this, the rate of absorption of mono- and disaccharides in the intestine decreases, and this protects the body from sharp increase blood glucose levels and increased insulin synthesis, which stimulates the formation of fats.

Vegetable fibers contribute to the accelerated removal from the body of various foreign substances contained in food products, including carcinogens and various exo- and endotoxins, as well as products of incomplete digestion of nutrients. The fibrous-capillary structure of ballast substances makes them natural enterosorbents.

Due to the absorption capacity, dietary fibers adsorb or dissolve toxins on themselves, thereby reducing the risk of contact of toxins with the intestinal mucosa, the severity of intoxication syndrome and inflammatory-dystrophic changes in the mucous membrane. Dietary fiber reduces the level of free ammonia and other carcinogens formed during putrefaction or fermentation or contained in food. Since plant fibers are not absorbed in the intestines, they are quickly excreted from the body with feces, and at the same time, the compounds sorbed by them are also evacuated from the body.

Due to their ion-exchange properties, dietary fibers remove heavy metal ions (lead, strontium), affect the electrolyte metabolism in the body, and the electrolyte composition of feces.

Microflora. Dietary fiber is the substrate on which bacteria grow. intestinal microflora, and pectins are also nutrients for these bacteria. The normal intestinal microflora includes several hundred species of bacteria. Dietary fiber is used by beneficial intestinal bacteria for their vital functions; as a result of this, the number of bacteria necessary for the body increases, which has a positive effect on the formation stool. At the same time, beneficial bacteria form the substances necessary for the human body (vitamins, amino acids, special fatty acid used by intestinal cells).

Some opportunistic bacteria metabolize nutrients through the biochemical processes of putrefaction and fermentation. Pectins suppress the vital activity of these microorganisms, which contributes to the normalization of the composition of the intestinal microflora. Dietary fibers stimulate the growth of lactobacilli, streptococci and reduce the growth of coliforms, affect the metabolic activity of normal microflora.

From ballast substances, bacteria form short chain fatty acids (SCFA) - (acetic, propionic and oily), which are a source of energy for the intestinal mucosa, protecting it from dystrophic changes, increasing the absorption of vitamin K and magnesium.

Table 1. Some effects of low molecular weight metabolites of microflora

Effect	Metabolites responsible for the effect
Energy supply of the epithelium	Acetic (acetate), butyric (butyrate) acid
Antibacterial effect
Regulation of proliferation and differentiation of the epithelium	Butyric acid (butyrate)
Supply of substrates for gluconeogenesis	Propionic acid (propionate)
Supply of lipogenesis substrates	Acetate, butyrate
Blocking the adhesion of pathogens to the epithelium	propionate, propionic acid
Regulation of intestinal motility	SCFA, salts SCFA, GABA, glutamate
Strengthening local immunity	Butyrate (butyric acid)
Maintenance of ion exchange	SCFA, SCFA salts (mainly acetic acid (acetate), propionic acid (propionate), butyric acid (butyrate)

Indigestible carbohydrates also reduce the bacterial breakdown of the protective intestinal mucus.

Dietary fiber increases synthesis of vitamins B1 , B2 , B6 , RR , folic acid intestinal bacteria.

Dietary fiber is a source of potassium and has a diuretic effect, that is, it helps to remove water and sodium from the body.

Deficiency of dietary fiber in the diet is considered one of the many risk factors for the development of various diseases: irritable bowel syndrome, hypomotor dyskinesia of the colon, functional constipation syndrome, colon and rectal cancer, intestinal diverticulosis, hernia esophageal opening diaphragm, cholelithiasis, atherosclerosis and related diseases, obesity, diabetes mellitus, metabolic syndrome, varicose veins and thrombosis of the veins of the lower extremities and a number of other diseases.

5. Norms of consumption of indigestible polysaccharides

Alimentary fiber nutrients now recognized as an essential component of nutrition.

For a long time, indigestible carbohydrates were considered unnecessary ballast, therefore, in order to increase the nutritional value, special technologies were developed to free food products from ballast substances. Refined food products have become widespread, especially in economically developed countries. In the 20th century, they began to produce and still produce refined products, completely or almost completely freed from dietary fiber: sugar, many confectionery products, fine flour, clarified juices of fruits, berries and vegetables, etc. As a result of this, at present, the majority of the world's population is experiencing a "westernization" of the diet: 60% or more of the daily diet is refined foods, with such nutrition, 10-25 g of dietary fiber per day enters the body. In a typical American diet, the amount of dietary fiber consumed is 12 grams per day. With this diet, the use of dietary fiber is significantly reduced against the background of an increased intake of proteins and animal fats.

In our country, over the past 100 years, the consumption of dietary fiber has decreased by more than two times.

According to nutritionists, almost all inhabitants of the planet suffer from fiber deficiency today. Excessive passion for refined products of the century was the reason for a significant increase in the prevalence of the so-called diseases of civilization: obesity, diabetes, atherosclerosis, diseases of the colon.

The diet of an average statistical modern person includes from 5 to 25 g of HP, on average 12-15 g. The diet of vegetarians of HP contains up to 40 g per day. And our ancestors consumed from 35 to 60 g. The source of HP was mainly nuts, grains and berries. Fruits and vegetables are the main source of HP these days.

AT hygiene requirements safety and nutritional value food products, approved by the Ministry of Health of Russia in 2001, the estimated physiological need for dietary fiber is defined as 30 g / day with an energy value of the diet of 2500 kcal. AT guidelines State Research Institute of Nutrition of the Russian Academy of Medical Sciences from 2008, the physiological need for dietary fiber for an adult is determined at 20 g / day. The American Dietetic Association recommends 25-30 grams of fiber per day. According to WHO recommendations, the accepted norm is the intake of 25-35 g of PV per day with food eaten. Therapeutic dose of PV - no more than 40-45 g per day, maximum daily dose- 60 g per day.

To provide the required amount of dietary fiber, the daily diet of each person should include 200 g of wholemeal bread, 200 g of potatoes, 250 g of vegetables and 250 g of fruit.

Of particular importance is the enrichment of diets with plant fibers in the elderly and in people with a tendency to constipation.

In chronic diseases of the colon, an increase in the amount of dietary fiber in the diet is required.

6. Dietary Sources of Indigestible Carbohydrates (ICs)

CONTENT OF DIETARY FIBER IN PRODUCTS

Dietary fiber is found only in plants. Animal products (meat, milk and dairy products) do not contain dietary fiber.

90% of our diet consists of foods that do not contain HP at all: meat, dairy products, fish, eggs, etc. Only 10% of the daily diet gives a chance to get as much PV as the body needs.

Plant products differ significantly in the quantity and quality composition of dietary fiber contained in them. In different herbal products contains dietary fiber different types. Only with a varied diet, i.e. when introduced into the diet of several types plant food(cereals, whole grain bread, vegetables, fruits, herbs), the body receives both the required amount of dietary fiber and fibers with different mechanisms of action.

The foods with the highest content of cell membranes include: wholemeal bread, millet, legumes (green peas, beans), dried fruits (especially prunes), beets. Significant amounts of cell membranes also contain buckwheat and barley groats, carrots. Largest Quantities pectins are found in apples, plums, black currants and beets. Foods rich in various ballast substances also include: nuts (almonds, peanuts, pistachios), cabbage, apricots, blackberries, coconut, kiwi, parsley, popcorn, seaweed.

A low content of cell membranes are characterized by: rice, potatoes, tomatoes, zucchini.

Table 2. The content of dietary fiber in some vegetables, the edible part of fruits and berries (Weinstein S.G., 1994)

Name	Number of PV in 100 g of the product, g		HP components, %
Name	Wet weight	Dry weight	Cellulose	Hemicellulose	lignin
Vegetables
Cabbage Brussels		35,5
winter cabbage		24,4
white cabbage		27,4
Onion		18,1			Traces
Peas frozen		37,1
green peas		47,6			Traces
Carrot		28,4			Traces
Swede		22,1

I will explain in a very simple way why dietary fiber is good for the body and how it helps in weight loss.

Dietary fiber (fiber) is a type of carbohydrate found in plants. But unlike carbohydrates, which are found in starchy and sugary foods, fiber is almost insoluble. gastric juice in the intestinal tract. Why is it important? Because the body cannot digest fiber, it passes almost unchanged through the stomach, intestines, and is eliminated from the body.

There are two forms of fiber: soluble and insoluble. Studies have shown that soluble fiber lowers cholesterol, which may help prevent heart disease. Insoluble fibers do not dissolve in water, are less susceptible to the fermentation process. Both forms of fibers are important.

Why dietary fiber is good for the body

Do you know everything about the benefits of fiber for our body? What role does dietary fiber play in the digestion process, and why are we always advised to include more fiber in our diet? ?

Fiber - contributes to weight loss and normalization. Swelling in the stomach, promotes rapid saturation, the appearance of a feeling of satiety (eating fewer calories).
Fiber - removes toxins. Passing through the small and large intestines, fiber binds toxins, carcinogens and removes them from the body.
Fiber – Helps control blood sugar levels. Fiber is a complex carbohydrate that, once in the stomach, slows down the absorption of carbohydrates.
Fiber is food for the good bacteria in our gut, so fiber supports a healthy correct work intestines. Increases immunity.
Fiber - lowers the level of cholesterol in the body.

Products containing soluble dietary fiber (per 100 grams):

Beans - 15g
Barley - 15.6g
Peas - 26g
Soy - 9.3 g
Buckwheat porridge - 17g
Lentils - 31g
Oatmeal - 10.6g
Rice - 1.3g
Beetroot - 2g
Apple - 2.4g
Potato - 2.2g
Walnut - 6.7g
Bananas - 2.6g
Celery - 2g
Mushrooms - 1g

Products containing insoluble dietary fiber (per 100 grams):

Barley - 15.6g
Brown rice - 3.5g
Wheat bran - 14g
Whole grain bread - 5g
Tomatoes - 1.2g
Cabbage (white, broccoli, cauliflower) - 2.5g
Carrot - 2.8g
Green beans - 2g
Onion - 1.7g
Raisins - 6g
Artichoke - 8.6g

Dietary fiber in our family's diet

The body should receive 30 - 38 g of fiber per day. Why don't many people pay attention to this? AT natural products very little fiber, technological progress reduces the usefulness of our products that we eat. I add fiber to my diet. Lack of time and a busy work day, do not allow you to eat right amount fiber. We increase the lack of dietary fiber in our family using and, which you can read about on my website.

By adding dietary fiber to your diet, you can feel full faster and longer, this helps to reduce and control weight. If you increase the amount of healthy fiber in your diet, you will significantly improve your health and will be able to easily control your weight.

Why is dietary fiber good for the body? The answer is simple: without these substances digestive system unable to function normally. They remove toxins and toxins from the body, increase resistance to pathogenic bacteria and infection.

In addition, regular consumption of food that contains dietary fiber helps to reduce body weight. This article will reveal all the necessary information about dietary fiber that every person needs to know.

The value of dietary fiber for the body

To begin with, it is necessary to explain what dietary fiber is?

In other words, it is fiber, which is a substance of plant origin. It is found in vegetables, fruits and grains. It does not contain minerals, vitamins, proteins and other nutritional components.

Dietary fiber, getting into the intestines, is not dissolved by gastric juice. They are eliminated from the body in an almost unchanged form. Nevertheless, nutritionists agree that the benefits of eating fiber are very large. It performs several important functions:

Aid in the normal functioning of the intestines. Once in the gastrointestinal tract, dietary fiber “absorbs” toxic substances and removes them from the body. Thanks to this process, the processing and assimilation of food improves.
The role of "food" for bacteria living in the intestine. With the help of fiber, intestinal bacteria synthesize amino acids, micro-, macroelements, vitamins and hormones.
Appetite control. By eating a small portion of a dish containing dietary fiber, you can get enough for a long time and forget about hunger. Therefore, fiber intake is beneficial in weight loss.
Normalization of intestinal microflora. It is an indisputable fact that 80% of all immune cells live in it. Improving the intestinal microflora leads to an increase in the body's defenses.
Decreased glycemic and cholesterol levels. Regular intake of dietary fiber prevents the occurrence of diabetes and cardiovascular pathologies.

Types of dietary fiber

There are two types of fiber - soluble and insoluble.

Each type of dietary fiber is important for the body and must be present in the diet.

When ingested, soluble fibers absorb moisture and increase in size. They become sticky and thick. To make it clearer, you can recall the process of making oatmeal.

When soluble fiber swells, it fills all the space in the stomach, and the person feels full.

Soluble fiber should be consumed because:

it promotes healing of the intestinal mucosa;
it removes toxins from the body;
it reduces putrefactive processes in the intestines.

Insoluble fibers pass through the gastrointestinal tract, practically do not absorb moisture and do not change in size. They must be introduced into the diet in order to:

stimulate peristalsis of the stomach;
remove excess cholesterol;
stimulate bile secretion;
create a feeling of satiety.

Below is a table that lists foods that contain soluble and insoluble fiber. It will help you make the right diet.

Soluble fiber		insoluble fiber
Products	Content in 100 grams (g)	Products	Content in 100 grams (g)
beans	15	brown rice	3,5
peas	26	tomatoes	1,2
buckwheat	17	wheat bran	14
soy	9,3	carrot	2,8
potato	2,2	raisin	6
barley	15,6	whole wheat bread	5
oatmeal	10,6	cabbage	2,5
lentils	31	onion	1,7
rice	1,3	artichoke	8,6
bananas	2,6	oat bran	10
beet	2	Strawberry	1,5
Apple	2,4	parsley	4
Walnut	6,7	zucchini	1,4
celery	2	white beans	3,8
mushrooms	1	corn	1,4

Normally, you need to consume 25-30 grams of fiber per day. Unfortunately, the daily diet of a modern person includes at most 12-15 grams of dietary fiber. All because of the use of fast food, in which there is practically no useful substances. Since the benefits of fiber are simply priceless, you should eat fresh fruits and vegetables every day.

If a person, without previously consuming dietary fiber in the required quantities, decided to dramatically increase their intake, it is better not to do this. This may cause discomfort in the form eating disorder(flatulence or diarrhea).

The intake of dietary fiber should be increased gradually to maximize the benefits. You are allowed to increase your fiber intake by 5 extra grams each day. The following recommendations will help in filling the diet with healthy fiber:

Vegetables should be consumed three times a day - for breakfast, lunch and dinner.
Fruit should be eaten with the skin on. When preparing a drink, the skin is also left, and it turns out not just juice, but smoothies.
During a snack, you need to eat only fruits.
White flour pastries are completely excluded from the diet. It does not contain dietary fiber at all, since during processing it is cleaned of the outer layer of grains. They just have fiber, so you should switch to bread, whole grain bread and muesli.
You need to give up chocolate, cookies, sweets and other sweets. They will be replaced by nuts and dried fruits.
You should add variety to the diet with bran, because they contain a huge amount of dietary fiber. For example, bran can be added to any drink.
Polished rice is best replaced with black or brown rice, beans, millet, barley, lentils, that is, unpeeled grains.
Products need to be cut not very finely, because fiber is destroyed during prolonged heat treatment.
Twice a week, you should replace the meat dish with legumes. Beans can even be cooked in a slow cooker. while cooking? Doctors believe that legumes prepared in this way will not bring damage to health.

It is best not to succumb to any processing of fruits and vegetables. But if a person has a too sensitive stomach, then he can boil fruits and vegetables until half cooked. This will help preserve the maximum of useful elements in the products.

Dietary fiber is the most valuable substance that must be present in the diet. Their benefits are undeniable - they improve the intestinal microflora, its work, remove toxic substances, increase the body's defenses. Regular consumption of fiber helps to say goodbye to excess pounds faster, as well as prevent diabetes and heart problems. Constant monitoring of the intake of healthy dietary fiber will provide a beautiful figure, improve digestion and human health in general!