Carbohydrate metabolism and the effects of dietary fiber: A scientific pathway from maintaining blood glucose homeostasis to regulating satiety.

Carbohydrates, also known as sugars, are named for their content of carbon, hydrogen, and oxygen, with the hydrogen-to-oxygen ratio being the same as that of water. Carbohydrates are classified into three categories: monosaccharides, disaccharides, and polysaccharides. Monosaccharides are the most common and simplest carbohydrates, including glucose, fructose, galactose, and mannose. They are easily soluble in water and can be directly absorbed and utilized by the body without the aid of digestive juices. Blood glucose in the human body is glucose, a monosaccharide. Common disaccharides include sucrose, maltose, and lactose. They are composed of two monosaccharide molecules, are easily soluble in water, and must be broken down into monosaccharides before they can be absorbed and utilized by the body.

Polysaccharides mainly include starch, dextrin, and glycogen. Starch is a major component of the diet, while glycogen is the main form of sugar stored in the body's cells. The liver and muscles store relatively large amounts of glycogen, called liver glycogen and muscle glycogen, respectively (normal adults store 100 grams and 200-400 grams, respectively). In addition, dietary fiber is also a type of carbohydrate, but it does not produce energy and is not absorbed; however, it helps food move smoothly through the digestive system. What are the functions of carbohydrates? Providing energy: The main function of carbohydrates is to provide heat; 60%-70% of the body's required energy comes from carbohydrates. Each gram of glucose produces approximately 4 kilocalories (16 kilojoules) of energy upon breakdown.

Constituting Cells and Tissues: Every cell contains carbohydrates, ranging from 2% to 10%, primarily in the form of glycolipids, glycoproteins, and proteoglycans, distributed in the cell membrane, organelle membranes, cytoplasm, and intercellular matrix. Conserving Protein: Insufficient carbohydrates in the diet force the body to utilize protein to meet its energy needs, which can hinder the synthesis of new proteins and tissue renewal. Therefore, completely eliminating staple foods and consuming only meat is not beneficial. For those trying to lose weight or with diabetes, the minimum carbohydrate intake should not be less than 150 grams of staple foods.

Maintaining normal brain cell function: Glucose is an essential nutrient for maintaining normal brain function. When blood sugar levels drop, brain tissue may lack energy, leading to impaired brain cell function, causing dysfunction, dizziness, palpitations, cold sweats, and even coma. Detoxification: Glucuronic acid, produced from carbohydrate metabolism, can bind with toxins in the body (such as drugs and bilirubin), thus aiding in detoxification. Strengthening intestinal function: Related to dietary fiber, it can prevent constipation, prevent colon and rectal cancer, and prevent hemorrhoids.

For healthy individuals who enjoy exercise, a diet consisting of 4-5 grams of carbohydrates per kilogram of body weight is a scientifically sound approach. Excessive carbohydrate consumption leads to glycogen storage. When this exceeds the body's glycogen stores, the excess glucose is stored as fat, thus causing weight gain and potentially leading to obesity-related diseases such as high cholesterol, fatty liver, diabetes, coronary heart disease, and hypertension. Furthermore, the type of carbohydrates you choose is crucial! The carbohydrates in grains, tubers, and legumes are primarily starch, which requires more steps to break down, resulting in slower digestion and absorption.

Blood sugar levels won't rise too quickly, meaning the glycemic index is relatively low. In contrast, monosaccharides and disaccharides (mainly from added sugars and processed foods) have a higher glycemic index, causing a rapid rise in blood sugar levels after ingestion. This rapid rise in blood sugar leads to a surge in blood insulin levels, which can cause health problems in the long run. Dietary fiber refers to the portion of plant-based foods that cannot be digested and absorbed by the human body; it helps maintain the normal functioning of the digestive system. Dietary fiber can be divided into two categories: soluble fiber and insoluble fiber. Soluble fiber: It can break down into colloids in water. Fruits, vegetables, legumes, oats, and bran all contain this type of fiber.

Insoluble fiber: It does not dissolve in water but can absorb water from the body, promoting excretion. This type of fiber is found in fruits, vegetables, whole grains, and wheat bran. The physiological functions of dietary fiber include: facilitating bowel movements. Dietary fiber has a strong water-absorbing capacity, which can increase the volume of feces in the intestines, promote intestinal peristalsis, prevent constipation, and shorten the contact time between harmful substances in feces and the intestinal wall, thereby reducing the incidence of colitis, proctitis, and colon and rectal cancer.