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Dietary fiber is a special nutrient whose essence is a polysaccharide substance in carbohydrates that cannot be decomposed by human digestive enzymes. There are hundreds of types of dietary fiber, including cellulose, hemicellulose, pectin, lignin, gum and vegetable viscose, algae polysaccharides, etc.
"All-rounder" for maintaining intestinal health.
The intestine is the largest immune organ in the human body, and 70% of the lymph is distributed in the intestine. The protective effect of dietary fiber on the intestinal tract should not be underestimated. The age of the intestine is mainly defined by the beneficial bacteria in the intestine The ratio of the group to the harmful bacteria group is used as the basis for judgment. The dietary fiber can promote the growth of beneficial bacteria and inhibit the reproduction of harmful bacteria, thereby maintaining normal intestinal function.
In addition, if the food stays in the intestine for too long, harmful substances and decomposed enzymes produced by intestinal microbial metabolism will be in contact with the intestinal mucosa for a long time. Will cause the absorption of harmful substances and damage the mucosal cells. Stool stays in the intestine for too long, and the absorption of various toxins can lead to intestinal tumors. The dietary fiber can make the food in the intestine swell and soften, promote intestinal peristalsis and defecation, so it reduces the residence time of carcinogens in the intestine and can prevent intestinal cancer.
A powerful weapon to treat diabetes.
Through scientific research, soluble dietary fiber has an outstanding contribution to reducing blood sugar and cholesterol concentration after meals. Because dietary fiber can greatly increase the gastrointestinal transit time, and the volume increases after water absorption and has a certain viscosity, so it delays the absorption of glucose. In the past, most of the healthiest foods for diabetic patients were insoluble fiber, but now the wide application of soluble dietary fiber will further improve the diet quality and therapeutic effect of diabetic patients.
Prevention of cardiovascular and cerebrovascular diseases.
Cholesterol in the liver will be converted into bile acid, which can help digest fat after reaching the small intestine, and then bile acid will return to the liver and be converted into cholesterol. Soluble fiber prevents bile acid from being absorbed by the intestinal wall of the small intestine but excreted through the digestive tract. Therefore, when the food in the intestines is digested, the liver can only absorb the cholesterol in the blood to supplement the bile acid, thereby reducing the cholesterol content in the blood. As a result, the incidence of coronary heart disease and stroke will also be greatly reduced.
Reduce the occurrence of gallstones.
The cause of gallstone formation is an excessive synthesis of cholesterol and too little synthesis of bile acids. Increasing dietary fiber can reduce the cholesterol content in bile, reduce the reabsorption of bile acid, and prevent gallstones effect.
Plays the role of weight loss.
While controlling energy intake, functional sugar is also one of the best ingredients for weight loss. For most fiber-rich foods, such as cereals, whole wheat noodles, beans, fruits, and vegetables.
The amount of fat. Experimental results prove that supplementing the diet with wheat bran, guar gum, pectin, etc. can cause a large amount of fat to be excreted.
Viscous fiber slows the absorption of carbohydrates, prevents the rapid rise in blood sugar after meals, and affects amino acid metabolism, thereby reducing weight.
In addition, another reason why dietary fiber is a good ingredient for weight loss is the volume of weight-loss dietary fiber can reach dozens of times after absorbing water, and there will be a feeling of fullness after eating, which can help obese people fight hunger and have the effect of losing weight.
Fit skin.
The harmful substances such as lactic acid and urea produced by the human body in the metabolism process once spread to the surface of the skin with sweat, the skin loses its vitality and becomes loose and dull. And dietary fiber
It can promote metabolism, detoxify the human body, and is beneficial to the health of the skin.
Is good for oral health.
Eat foods high in dietary fiber and chew for a long time, so that while you can better enjoy its deliciousness, your teeth and periodontal tissues will also get good activity and exercise.
Inhibit the absorption of cholesterol.
Sufficient intake of dietary fiber can inhibit the absorption of cholesterol, absorb a large amount of cholesterol and take it out of the body, which is conducive to maintaining the function of the cardiovascular system and can prevent diabetes, hyperlipidemia, etc. Control the disease.
Prevent cancer.
Dietary fiber shortens the residence time of feces in the large intestine and has the functions of detoxification and detoxification, which reduces the chance of carcinogens in the large intestine from contacting the intestinal wall and promotes its rapid excretion.
Improve immunity.
There are a large number of microorganisms in the human intestine, including probiotics that are beneficial to health. They can produce essential nutrients such as vitamin K, and improve the body's immune function.
Although dietary fiber is not absorbed by the body. However, after reaching the large intestine, it can be decomposed and used by microorganisms to become the bait for microorganisms, which promotes its growth and reproduction, which is beneficial to health.
The classification and function of dietary fiber
Dietary fiber
Definition: Dietary fiber (DF) is a polysaccharide and lignin that are not digested by digestive enzymes secreted by the human digestive tract and are not absorbed by the body.
(1) Classification of dietary fiber
DF includes a large class of substances with similar physiological functions, and dietary fiber can be divided into soluble dietary fiber and insoluble dietary fiber according to solubility.
Soluble dietary fiber is mainly
①Storage substances and secretions in plant cell walls
②Part of hemicellulose
③Some microbial polysaccharides
④Synthetic polysaccharides, such as gum, konjac polysaccharide, guar gum, arabinose, etc.;
Insoluble dietary fiber includes
① Hemicellulose
②Insoluble hemicellulose
③Lignin
④ Resistant starch
⑤Some indigestible oligosaccharides
⑥Product of Maillard reaction
⑦Chitin contained in the epidermis of shrimp, crab, and other animals
⑧Wax and cutin of plant cell wall
⑨Indigestible cell wall protein.
1.Cellulose is similar to starch in chemical structure. It is a linear polymer linked by β-1,4 glycosidic bonds, which cannot be decomposed by human intestinal amylase. Herbivores can use the function of cellulose because the microorganisms in their rumen can produce cellulase.
2. Hemicellulose, like cellulose, is mainly connected by β-1,4 glycosidic bonds, but also β-1,3-glycosidic bonds, which can be divided into xylan according to the different monosaccharides contained in the main chain and branch chains, Galactan, mannan, and arabinose polymer. Some also contain galacturonic acid and glucuronic acid.
3. Lignin Although lignin is included in the category of crude fiber and unusable carbohydrate, it is not a real carbohydrate, but a complex polymer of phenyl-propane derivatives, which is composed of cellulose and hemicellulose. The cell wall of a plant.
4. Pectin (pectin) The main chain component of pectin is galacturonate, and the typical side chains are galactose and arabinose. It is an amorphous substance that exists in the soft tissues of vegetables and fruits. It can be dissolved in a hot solution, and it forms a gel when heated in an acidic solution, and is used as a thickener in food processing.
5. Resistant starch (RS) includes modified starch and starch that has been cooled and heated. Resistant starch is very similar to dietary fiber in physiological function, so it is classified as dietary fiber. It belongs to insoluble dietary fiber, but usually has the characteristics of soluble dietary fiber. It can be used as a slow release agent of glucose to reduce postprandial blood sugar. Animal studies have shown that resistant starch can promote the growth of probiotics and increase the number of Bifidobacterium coli in vivo and in vitro.
6. Non-digestible oligosaccharides Non-digestible oligosaccharides (NDO) are short-chain polysaccharides synthesized from 3 to 9 monosaccharides with physiological regulation. These polysaccharides may be formed by polymerization of the same or different monomers and connected by different bonds. NDO is a natural component of certain plants such as legume seeds and grains (raffinose-present in honey, and one of the components of soybean oligosaccharides, stachyose). In addition, NDO can also be produced as a functional additive in feed and food. For example, fructooligosaccharide (FOS) can be prepared by partially hydrolyzing inulin, and galactooligosaccharide (TOS) can be prepared from lactose.
The physiological functions and chemical properties of NDO depend on its chemical composition. Most of NDO is soluble in water, ethanol and body fluids, but it is quite stable under pH conditions in the body. The nutritional function of NDO comes from its unique fermentation quality, which is also called bifidus factor. Cellulose and hemicellulose do not have similar functions, which may be caused by heterogeneity. The non-specific stimulating effect of NDO on exogenous sources can prevent the establishment of undesirable microflora.
7. Gum and mucilage are composed of different polysaccharides and their derivatives. Acacia gum (arabicgum) and guar gum (guargum) belong to this category of substances, which can be used as stabilizers in food processing.
(2) Nutritional function of dietary fiber
1. The physical and chemical properties of dietary fiber
(1) Water holding capacity: The chemical structure of DF contains many hydrophilic groups, so it has a strong ability to absorb water and expand. DF expansion can fill the gastrointestinal tract and increase satiety. The water holding capacity of different DFs is also different, and the water holding capacity of soluble DF is stronger than that of insoluble DF. After soluble DF absorbs water, its weight can increase to 30 times its original weight, and can form sols and gels, increase the viscosity of the contents in the stomach and intestines, and delay the emptying speed of the chyme in the stomach. Soluble DF can significantly prolong gastric emptying time, while insoluble DF has no such effect.
(2) Combining and exchanging ions: The chemical structure of DF contains some carboxyl groups, aldehyde groups and hydroxyl side chain groups, which act as weakly acidic cation exchange resins. It can combine with cations such as calcium, magnesium, and zinc to make sodium ions and Potassium ion exchange, especially reversible exchange with organic ions.
(3) Fermentation characteristics: DF can be fermented and decomposed to varying degrees by intestinal microorganisms. Different sources of DF are decomposed to different degrees, which is related to their water holding capacity and polysaccharide structure.
(4) Absorb and chelate organic compounds: DF has many active groups on the surface, which can adsorb and chelate bile acids, cholesterol, mutagen and other organic molecules. The adsorption capacity of bile acids is stronger with lignin and weaker with cellulose. . At the same time, DF can also absorb toxic substances in the intestine and promote their excretion.
2. The physiological role of dietary fiber
(1) Increase satiety and reduce the absorption of other nutrients: DF enters the digestive tract, absorbs water and expands in the stomach, increases gastric motility, delays the speed of stomach contents entering the small intestine, and reduces the small intestine's absorption of nutrients speed. At the same time, it makes people feel full, which is beneficial to reducing food intake for patients with diabetes and obesity.
The DF that enters the small intestine from the stomach can hardly be broken down by digestive enzymes and continues to move to the lower intestine. In the meantime, DF has a certain effect on the hydration of intestinal contents, the emulsification of lipids, and the digestion of digestive enzymes. It also hinders the digestion of food masses and the absorption of nutrients, which can form high viscosity. Sol and gel water-soluble dietary fiber has a stronger effect.
DF, which has the ability to bind to cations, can hinder the absorption of inorganic salts in the intestinal tract, while alginic acid (a soluble DF) with ion exchange capacity can adsorb sodium salts and be excreted with feces, thereby reducing blood pressure.
(2) Lower blood cholesterol, prevent gallstones, hyperlipidemia and cardiovascular disease: DF can hinder the absorption of neutral fat and cholesterol, and has a preventive effect on dietary hyperlipidemia. DF can reduce the reabsorption of bile acids, which can change the speed of food digestion and the secretion of secretions in the digestive tract, play a role in preventing gallstones, preventing hyperlipidemia and cardiovascular diseases.
(3) Prevention of diabetes: The viscosity of soluble DF can delay the absorption of glucose, inhibit the rise of blood sugar, and improve glucose tolerance.
DF can also increase the sensitivity of tissue cells to insulin and reduce the need for insulin, thus having a certain effect on diabetes prevention.
(4) Change the intestinal flora: DF entering the large intestine can be partially and selectively decomposed and fermented by intestinal bacteria, thereby changing the composition and metabolism of the intestinal microflora and inducing the proliferation of beneficial flora.
(5) Promote bowel movement and prevent bowel cancer and breast cancer: The short-chain fatty acids produced by the fermentation of microorganisms can lower the pH of the intestine, which not only promotes the reproduction of beneficial bacteria, but also stimulates the intestinal mucosa. Thereby promoting fecal excretion. Because DF absorbs water, it can increase stool volume and weight, promote intestinal peristalsis, reduce stool hardness, increase bowel frequency, reduce pressure in the rectum, and reduce the time that stool stays in the intestine. It can prevent diverticulosis, constipation, and long-term constipation. Hemorrhoids and varicose veins of the lower extremities. At the same time, it reduces the pressure on the urinary system and relieves the symptoms of urinary system diseases such as cystitis, bladder stones and kidney stones. Due to the laxative effect of DF, the metabolites of bacteria in the intestines, as well as some carcinogens converted from bile acids, such as deoxybile acid, lithocholic acid, and mutants, can be excreted with DF.
(6) Beauty and beauty. Because it can absorb water and swell, the metabolites in the intestine will become softer and looser, and it will pass through the intestine faster. At the same time, it can promote intestinal peristalsis, reduce the absorption of harmful substances, and remove toxins from the body. Improve "face problems" such as getting angry, bad breath, facial acne, pimples, rough skin, and pigmentation.
Studies have shown that different types of dietary fiber have different adjuvant therapeutic effects. JoannelSlain’s research shows that insoluble dietary fiber from fruits, vegetables, and grains can be used to treat constipation. The water-soluble dietary fiber in oats and flaxseed can lower cholesterol, and the dietary fiber in wheat bran is better than other fibers in preventing colon cancer. effective.
When people have symptoms and diseases such as constipation, indigestion, hemorrhoids, diabetes, obesity, arteriosclerosis, hypertension, gallstones, etc., they should pay attention to increasing dietary fiber intake.
(3) Food sources and supply of dietary fiber
1.Food sources Dietary fiber mainly exists in cereals, potatoes, beans, vegetables and fruits. Cereal foods contain the most dietary fiber. Whole wheat flour contains 6%, refined flour contains 2%, brown rice contains 1%, polished rice contains %, and vegetables contains 3 %, fruits contain about 2%. However, the content of dietary fiber is also different due to the difference in processing methods, ingested parts and varieties. Coarse grains and legumes are higher than fine grains; carrots, celery, spinach, leeks, etc. are higher than tomatoes, eggplants, etc.; pineapples and strawberries are higher than bananas, apples, etc.; the fiber content in the edge of the same vegetable is higher than that of the center, and the peel of the same fruit The amount of fiber is higher than the pulp. If the rind of the vegetable or fruit is removed when eating, part of the dietary fiber will be lost. Fruit juice and slag should be eaten together. The amount of dietary fiber in a citrus is about 6 times that of orange juice. Therefore, people should reasonably mix coarse and fine grains and eat more vegetables and fruits so that the supply of dietary fiber can generally meet the needs of the human body.
2. supply
The World Health Organization puts forward that the daily total dietary fiber intake for adults is 27-40g. China’s dietary survey proves that the average daily intake of dietary fiber per capita in China has dropped from 26g in the past. The reason is that people are eating more and more refined. Many people only eat refined rice noodles and rarely care about coarse grains; Pay attention to the intake of protein, and pay little attention to the intake of fruits and vegetables. The decrease in dietary fiber intake has led to an increase in the incidence of the "wealthy disease" that was previously common in developed countries, and has become a major enemy threatening the health of our people.
my country has not yet proposed a clear recommended intake of dietary fiber standards. Among the DRIs launched by the Chinese Nutrition Society in 2000, the tentative recommended intake of DF for Chinese residents is: low, medium, and high-energy diet [intake 1800kcal, 2400kcal, 2800kcal> respectively 25, 30, 35g/d. In Japan, the daily intake of DF is 20~30g. In the intake of DF, attention should also be paid to the ratio of insoluble fiber to soluble fiber. The American Committee of Supply Experts recommends that the intake ratio of dietary fiber is 70% to 75% for insoluble fiber and 25% to 30% for soluble fiber. . So, how many grams of fresh fruits and vegetables can contain 30 grams of dietary fiber? For example: 2240 grams of apples, 2250 grams of bananas, 2100 grams of celery, 4000 grams of tomatoes, 4300 grams of cabbage, etc.
3. Side effects of excessive dietary fiber intake:
Excessive intake of dietary fiber will have some side effects, such as diarrhea, bloating, and abdominal pain. The rare side effects are the formation of fibrous fecal stones in the intestines and cause intestinal obstruction, which requires surgical treatment. This should be paid special attention to the elderly or extremely thin patients. Therefore, it should be advocated to gradually increase the intake of dietary fiber. At the same time, excessive intake of dietary fiber will affect the absorption of vitamins and trace elements. In addition, people suffering from acute chronic enteritis, typhoid fever, dysentery, colonic diverticulitis, intestinal tumors, gastrointestinal bleeding, before and after intestinal surgery, intestinal stenosis, esophageal varices, and other diseases should control the intake of dietary fiber.
Three, development and application
Listed as the "seventh largest nutrient" after sugar, protein, fat, water, minerals and vitamins. Experts agree that fiber food will be one of the leading foods in the 21st century.
The functional beverage market and the application of dietary fiber: In recent years, the functional or nutritional beverage market has grown steadily in Japan. Due to the popularity and popularity of medicinal beverages, Japanese consumers now believe that beverages are not only used to quench their thirst, but also regard them as a good source of nutrition like vitamins. Nutritional beverages in Japan are like "vitamin tablets" for consumption in the United States. As important and welcomed. In 1988, the Japanese Volkswagen Pharmaceutical Company launched a beverage called "Fiber-Mini" to the market, which is polydextrose, a soluble dietary fiber, and a fiber beverage as a edible fiber component. Because of its successful sales strategy, it is particularly pointed out that it is a health-good drink, so it is generally welcomed as soon as it goes on the market. Before "Fiber-Mini" was launched, nutritious drinks were considered to be nourishing drinks for men. However, "Fiber-Mini", a drink containing dietary fiber, attracted many young Japanese women. Created a market with the flavor of "women's drinks".
In Japan, there are 11 best-selling functional drinks, and 6 of them contain dietary fiber. In fact, in the total sales of functional beverages, more than 70% of beverages contain dietary fiber. The survey found that almost half of the women in a company have constipation or frequent constipation. Constipation not only causes uncomfortable feeling, but also causes skin problems, which is the most concerned issue for young women. Therefore, beauty and laxatives may have a certain relationship.
Fibrous food is known as the "Oasis of Life". In recent years, the international food structure has been adjusted in the direction of fibrous food. Consumer demand in Japan and the United States is growing at a rate of 10% every year. In the European and American markets, adding soluble dietary fiber to food has been popular for many years, and sales of foods adding soluble dietary fiber to Japan, Taiwan, and South Korea are increasing. In China, soluble dietary fiber has been added to some drinks. It is certain that in the near future, dietary fiber drinks or health foods will be further developed in China.
The health effects of dietary fiber
Dietary fiber refers to a kind of plant food that cannot be digested by human digestive enzymes, nor absorbed by the small intestine, but can be partially digested and used by certain microorganisms in the large intestine. It is a general term for polysaccharides as the main polymer.
Dietary fiber can generally be divided into two categories, one is water-soluble fiber and the other is insoluble fiber. Water-soluble fiber includes pectin in fruits such as apples and citrus, gluten in oat bran, barley bran, etc.; insoluble fiber includes cellulose, lignin and some semi-fibers, which are found in wheat bran, corn bran, celery, Peel and root vegetables. Studies have found that dietary fiber has high nutritional value and health benefits, and its relationship with human health has been paid more and more attention.
1. The health benefits of dietary fiber
①Improve oral and dental functions. Modern people have more and more refined and softer foods, and there are fewer and fewer opportunities to use oral muscles and teeth. Therefore, there are more and more cases of tooth loss and caries. Increasing the fiber in the diet naturally increases the chances of using oral muscles and teeth to chew, which can eliminate bad breath and achieve the effect of tooth-fixing and protecting teeth.
② Conducive to weight loss. Obesity is mostly related to excessive intake of calories in food or reduced physical activity. Increasing the dietary fiber content in the diet can increase the feeling of fullness, delay the speed of the stomach contents entering the small intestine, and also reduce the absorption speed of nutrients in the small intestine, and ultimately cause the consumption of body fat to reduce weight.
③Improve the symptoms of diabetes. The pectin in the dietary fiber can prolong the residence time of food in the intestine, reduce the absorption rate of glucose, and prevent the blood sugar from rising sharply after a meal. Dietary fiber can also increase the sensitivity of tissue cells to insulin and reduce the need for insulin , Is conducive to the improvement of diabetes. Recent studies have shown that dietary fiber has the effect of lowering blood sugar. Adding 26 grams of edible corn bran (containing fiber%) or soybean hulls (containing fiber%) to the diet every day will significantly improve glucose tolerance after 28-30 days. Studies have pointed out that dietary fiber can slow down the absorption of glucose in the small intestine by at least the following three ways: first, increase the viscosity of intestinal fluid and hinder the diffusion of glucose; second, reversibly absorb glucose and reduce the absorption of glucose in the intestine; third, Affect the degradation of starch by alpha amylase, prolong the enzymolysis time and reduce the rate of glucose release. Therefore, the long-term increase of dietary fiber in the diabetic diet can reduce the amount of insulin required and control the metabolism of blood sugar after a meal. This can be used as an auxiliary measure for the treatment of diabetes.
④Reduce blood lipids, prevent gallstones, hyperlipidemia and cardiovascular diseases. It is generally believed that increasing fecal bile excretion is the main mechanism for dietary fiber to reduce blood lipids and cholesterol. Some components of dietary fiber (if glue can bind cholesterol, lignin can bind bile acid) can hinder the absorption of fat and cholesterol, causing it to be directly excreted from the stool. Some people add 20 to 30 grams of grain fiber to the patient every day, and the gallstones can be found to shrink after one month, which is related to the smooth flow of bile.
⑤Prevent constipation and hemorrhoids. The chemical structure of dietary fiber contains many hydrophilic groups, which have strong water holding capacity. The high water-holding capacity of dietary fiber is beneficial to increase the water content and volume of feces, soften feces, reduce intestinal pressure, increase defecation frequency, reduce the residence time of harmful substances in the intestine, and promote fecal excretion, which is great for alleviating and preventing constipation. There are benefits. The occurrence of hemorrhoids is caused by long-term blood blockage and stasis due to constipation. Due to the laxative effect of dietary fiber, it can reduce the pressure around the anus and make blood flow smooth, thus playing a role in preventing and treating hemorrhoids.
⑥ Prevent colon cancer and rectal cancer. Scholars agree that a long-term diet based on high animal protein, coupled with insufficient intake of fiber, is an important cause of these two types of cancer. In the case of long-term constipation or high-fat diet, some carcinogens or accelerators (nitrosamines, phenols, indoles, secondary bile acids, estrogen, etc.) are often formed in the human large intestine. Bile acid is a promoter of colon cancer, and dietary fiber can combine with bile acid to reduce its absorption. In addition, the water-containing properties of dietary fiber soften the stool, reduce the friction damage between these carcinogens and the intestinal wall, and reduce the chance of cancer. In addition, short-chain fatty acids produced by colonic bacteria that can ferment fibers may have the potential to prevent colon cancer. Colon cells absorb butyric acid quickly and have specificity. Butyric acid is used as energy for colon cell metabolism to promote the proliferation of normal cells. Butyric acid can also inhibit the growth and proliferation of tumor cells and control the expression of oncogenes.
2. Food sources and supplies of dietary fiber
① Food sources
Plant foods are natural food sources of dietary fiber, such as brown rice and germ-polished rice, as well as miscellaneous grains such as corn, millet, barley, wheat husks (rice bran) and wheat flour (material of brown bread); in addition, food fiber in root vegetables and seaweeds More, such as burdock, carrot, string beans, red beans, peas, potatoes and wakame.
The content of dietary fiber in plant foods is also different due to different processing methods, eating parts and varieties. Whole wheat flour contains 6%, refined flour contains 2%, brown rice contains 1%, polished rice contains 3%, vegetables contain 3%, and fruits. Contains about 2%. Coarse grains and beans are higher than fine grains; carrots, celery, spinach, leeks, etc. are higher than tomatoes, eggplants, etc.; pineapples and strawberries are higher than bananas, apples, etc.; the skin of the same vegetable has higher fiber content than the center, and the peel of the same fruit The fiber content is higher than the pulp.
②Daily requirement
The daily intake of dietary fiber recommended by relevant international organizations varies. For example, the American Cancer Prevention Association recommends a standard of 30-40 grams per person per day; the European Community Food Science Committee recommends a standard of 30 grams per person per day; The daily dietary fiber intake stipulates 20-30 grams per person per day; the World Food and Agriculture Organization recommends that the normal population intake should be 27 grams per person per day; the World Health Organization proposes that the total dietary fiber intake for adults per day is 27-40 grams. my country's dietary survey shows that the average daily intake of dietary fiber per person in my country has dropped from 26 grams in the past to grams. The reason is that people are eating more and more refined. Many people only eat finely processed rice noodles and rarely care about coarse grains; they only pay attention to the intake of protein and pay little attention to the intake of fruits and vegetables. The decrease in dietary fiber intake has led to an increase in the incidence of the "wealthy disease" that was previously common in developed countries, and has become a major enemy threatening the health of our people.
my country has not yet proposed a clear recommended intake of dietary fiber standards. Among the dietary nutrient reference intakes released by the Chinese Nutrition Society in 2000, the tentatively recommended dietary fiber intake for Chinese residents is 25 to 35 grams per day. In addition, for patients with "riches disease", 10-15 grams/day should be added on this basis. For children and adolescents aged 2-20, the recommended intake is age plus 5-10 grams/day. In the intake of dietary fiber, attention should be paid to the ratio of insoluble fiber to soluble fiber. The American Committee of Supply Experts recommends that the intake ratio of dietary fiber is 70% to 75% insoluble fiber and 25% to 30% soluble fiber.
It should be reminded that the intake of dietary fiber is not the better. Excessive intake of dietary fiber will have some side effects, such as diarrhea, bloating, and abdominal pain. In severe cases, fibrous fecal stones can form in the intestines and cause intestinal obstruction, requiring surgery. Treatment, this point should be paid special attention to the elderly or extremely thin patients. Therefore, it should be advocated to gradually increase the intake of dietary fiber. In addition, excessive intake of dietary fiber will affect the absorption of vitamins and trace elements. It should also be pointed out that people with acute chronic enteritis, typhoid fever, dysentery, colonic diverticulitis, intestinal tumors, gastrointestinal bleeding, before and after intestinal surgery, intestinal stenosis, esophageal varices, and other diseases should control the intake of dietary fiber.
The physiological role of dietary fiber
With the improvement of people’s living standards and the enhancement of people’s health awareness, the concept of food consumption is constantly changing. People have paid more and more attention to the impact of diet on their own health. The consumption trend has changed from the best in color, fragrance, taste and shape. Foods have turned to foods with reasonable nutrition and health functions. Dietary fiber and its food, which are the functional factors of functional foods, have also received extensive attention and rapid development in countries around the world in recent years. Many food experts regard dietary fiber foods as functional foods and popular foods in the 21st century. Nutrition surveys show that insufficient intake of dietary fiber from food can lead to coronary heart disease, diabetes, high blood pressure, obesity, myocardial infarction, ischemic heart disease, colon cancer, colitis and constipation. These diseases occur frequently. With the improvement of people’s living standards
The chemical structure of dietary fiber contains some carboxyl and hydroxyl side chain genes, which act as a weakly acidic cation exchange resin, which can be reversibly exchanged with cations, especially organic cations.
Adsorption and chelation for organic compounds
There are many active genes on the surface of dietary fiber, which can chelate and adsorb organic molecules such as cholesterol and bile acid, thereby inhibiting the body's absorption of them. This is an important reason why dietary fiber can affect the metabolism of cholesterol in the body. At the same time, dietary fiber also absorbs toxic substances, chemicals and toxic drugs in the intestine and promotes their excretion from the body.
Has a volume effect similar to a filler
Dietary fiber cannot be digested and absorbed by the human body, and will not be converted into human storage materials. The volume of dietary fiber is larger, and the volume after binding water is larger, which has a volumetric effect on the intestinal tract, which can easily cause a feeling of fullness and reduce the body’s other nutrients. The intake of dietary fiber affects the body's digestion and absorption of other food ingredients, and people are less likely to feel hungry. For this reason, dietary fiber is beneficial to preventing obesity [3,4], and it has become a purely natural diet food recommended internationally.
viscosity
Pectin, β-glucan, various types of colloids, and seaweed polysaccharides of agar, etc., can make the intestinal tract form a highly viscous liquid, which makes the intestine viscous and slows down the emptying of the stomach. In the small intestine, the mixing of food can also be reduced. Even if the contact between the enzymes in the intestine and the food is reduced, the entry of nutrients into the intestinal mucosal cells is also reduced. This presents a slow response to the glucose tolerance test, that is, dietary fiber can reduce the glucose index.
The physiological role of dietary fiber
Regarding the physiological functions of dietary fiber, early research work has not been paid attention to. Until the 1960s, on the basis of a large number of research facts and epidemiological investigation results, the important physiological functions of dietary fiber were not understood and gradually recognized. Now it has been listed in the following areas: protein, carbohydrate, fat, The seventh nutrient after vitamins, mineral elements and water [9,10]. It is essential for the normal physiological metabolism of the human body.
Generally speaking, the physiological functions of dietary fiber can be briefly described as follows:
Lower cholesterol
Elevated serum cholesterol can lead to coronary heart disease. Blood cholesterol mainly comes from food intake and endogenous synthesis in the body; its main decomposition pathway is to convert into bile acid.
