Cellulose is the oldest and most abundant natural polymer on the earth. It is inexhaustible and the most precious natural renewable resource of mankind. Cellulose chemistry and industry began more than 160 years ago and is the main research object during the birth and development of polymer chemistry. The research achievements of cellulose and its derivatives have made significant contributions to the establishment, development and enrichment of polymer physics and chemistry.
1. Physiological function
Not in human body β- Glycosidase can not decompose and utilize cellulose, but cellulose can absorb a lot of water, increase the amount of feces, promote intestinal peristalsis, accelerate the excretion of feces, shorten the retention time of carcinogens in the intestine, and reduce the adverse stimulation to the intestine, thus preventing the occurrence of intestinal cancer.
2. Dietary fiber
Cellulose in human diet is mainly contained in vegetables and rough processed cereals. Although it cannot be digested and absorbed, it can promote intestinal peristalsis and facilitate fecal excretion. Herbivores rely on symbiotic microorganisms in their digestive tract to decompose cellulose, which can be absorbed and utilized. Food cellulose includes crude fiber, semi-crude fiber and lignin. Food fiber is a substance that cannot be digested and absorbed. It was considered as "waste" in the past. In 2013, it was believed that it plays an important role in protecting human health and prolonging life. Therefore, it is called the seventh nutrient.
Dietary fiber is generally made of various types of high-purity dietary fiber extracted from natural foods (konjac, oats, buckwheat, apples, cacti, carrots, etc.). The main functions of dietary fiber are:
(1) Treat diabetes
Dietary fiber can improve the sensitivity of insulin receptor and the utilization rate of insulin; Dietary fiber can wrap the sugar of food, make it gradually absorbed, and balance the blood sugar after meal, so as to regulate the blood sugar level of diabetes patients and treat diabetes.
(2) Prevention and treatment of coronary heart disease
The increase of serum cholesterol will lead to coronary heart disease. The excretion of cholesterol and cholic acid is closely related to dietary fiber. Dietary fiber can combine with cholic acid and make cholic acid rapidly excrete from the body. At the same time, the combination of dietary fiber and cholic acid will promote the conversion of cholesterol to cholic acid, thus reducing the cholesterol level.
(3) Hypotensive effect
Dietary fiber can adsorb ions and exchange with sodium and potassium ions in the intestine, thus reducing the ratio of sodium and potassium in the blood, thus lowering blood pressure.
(4) Anticancer effect
Since the 1970s, there have been more and more reports on the research of dietary fiber in anti-cancer, especially the relationship between dietary fiber and gastrointestinal cancer. Early surveys in India showed that people living in northern India consumed much more dietary fiber than those living in southern India, and the incidence rate of colon cancer was also much lower than that in southern India. According to this survey, scientists have done more in-depth research and found that there are several reasons for dietary fiber to prevent and treat colon cancer: some saprophytes in the colon can produce carcinogens, while some beneficial microorganisms in the intestine can use dietary fiber to produce short-chain fatty acids, which can inhibit the growth of saprophytes; Cholic acid and chenolic acid in bile can be metabolized by bacteria into carcinogens and mutagens of cells. Dietary fiber can bind substances such as cholic acid and expel them from the body to prevent the generation of these carcinogens; Dietary fiber can promote intestinal peristalsis, increase stool volume and shorten emptying time, thus reducing the chance of carcinogens in food contacting colon; The beneficial bacteria in the intestine can use dietary fiber to produce butyric acid, which can inhibit the growth and proliferation of tumor cells, induce the transformation of tumor cells to normal cells, and control the expression of carcinogenic genes.
(5) Lose weight and treat obesity
Dietary fiber replaces the amount of some nutrients in the food and reduces the total intake of food. Dietary fiber promotes the secretion of saliva and digestive fluid, plays a filling role in the stomach, while absorbing water and swelling, which can produce a feeling of fullness and inhibit appetite. Dietary fiber is combined with some fatty acids. This combination makes fatty acids cannot be absorbed when they pass through the digestive tract, thus reducing the absorption rate of fat.
(6) Treat constipation
Dietary fiber has strong water holding capacity, and its water absorption is up to 10 times. After absorbing water, it will increase the volume of intestinal contents, make the stool loose and soft, and make it smoother and easier to pass through the intestine. At the same time, dietary fiber, as an intestinal foreign body, can stimulate the contraction and peristalsis of the intestine, accelerate the excretion of stool, and play the role of treating constipation.
