Cholesterol is a derivative of cyclopentane dihydrophenanthrene. The chemical formula is C27H46O, which is a white or light yellow crystal. It is the main steroid compound in mammals and plays an important role in basic cellular life activities. It is an important indicator of clinical biochemical examination. Under normal circumstances, the cholesterol synthesized by the body in the liver and ingested from food will be converted into flutin hormone or become a component of the cell membrane, and the concentration of cholesterol in the blood will be kept constant. When severe liver disease occurs, cholesterol concentration will decrease. In patients with yellow pox obstruction and nephrotic syndrome, cholesterol concentration often increases. It is the main steroid compound in the body of mammals and plays an important role in the basic life activities of cells. On October 27, 2017, the International Agency for Cancer Research of the World Health Organization released a preliminary draft of the list of carcinogens, which included cholesterol in the three categories of carcinogens.
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There are two completely different and one-sided views on the role of food cholesterol. One view is that cholesterol is extremely harmful and inedible. The one-sided view is due to the lack of clear understanding of the role of cholesterol in the human body among those who hold this view. In fact, cholesterol is a component of cell membranes and participates in the biosynthesis of some body hormones and bile acids. Due to the abundance of other nutrients in many foods containing cholesterol, excessive consumption of such foods can easily lead to nutritional imbalance and the occurrence of anemia and other diseases.
Although cholesterol exists in animal foods, the content of cholesterol varies greatly among different animals and different parts of the animal. Generally speaking, the cholesterol content of livestock meat is higher than that of poultry meat, fat meat is higher than that of lean meat, shellfish and mollusks are higher than that of general fish, while the cholesterol content of egg yolk, roe, and animal organs is the highest.
Usually, foods with a cholesterol content of less than 100 milligrams per 100 grams of food are called low cholesterol foods, such as fish, carp, pig lean meat, beef lean meat, sheep lean meat, duck meat, etc; Foods with a cholesterol content of 100-200 milligrams per 100 grams of food are called moderate cholesterol foods, such as grass carp, unloaded fish, juvenile fish, yellow croaker, river steamed bun, turtle, crab meat, pork chops, chicken, etc; Foods with a cholesterol content of 200-300 milligrams per 100 grams of food are called high cholesterol foods, such as pig kidneys, liver, tripe, clam meat, pork, egg yolks, crab roe, etc. Patients with hypercholesterolemia should try to eat as little or no high cholesterol foods as possible.
Lowering cholesterol:
1. Eat less or avoid foods with high cholesterol levels such as animal organs and egg yolks, and control cholesterol intake in the diet (less than 300 milligrams per day). The main cholesterol in the blood (70%) is synthesized by the liver, and only a small portion (30%) comes from food. Therefore, reducing cholesterol intake alone cannot fundamentally treat high cholesterol. However, controlling the amount of cholesterol intake in food is still helpful in reducing cholesterol. According to the standards recommended by the American Heart Association, the daily intake of cholesterol should be less than 300 milligrams or less, while the cholesterol in one egg yolk is 250-290 milligrams, and the cholesterol content in 100 grams of boiled pork liver can reach up to 469 milligrams.
2. Eat less fat and fat, and reduce saturated fat intake. Saturated fat is widely present in meat, eggs, and dairy foods, especially in fat, meat oils, and viscera. Saturated fat has the effect of promoting the growth of low density lipoprotein cholesterol (LDL-C) in the blood, and its efficacy even exceeds that of cholesterol itself.
3. Eat more vegetables, fruits, and algae, such as konjac, black fungus, seaweed, Undaria pinnatifida, onions, pumpkins, sweet potatoes, etc. These foods are rich in dietary fiber and help with cholesterol excretion. The main pathway for cholesterol excretion in the human body is through bile, which is used by the liver to synthesize cholic acid. Cholic acid is discharged into the gastrointestinal tract along with bile to participate in fat digestion. Afterwards, some of the bile acid metabolites are re absorbed back into the bloodstream for "waste utilization", and another part of the bile acid metabolites are excreted from the body with feces. The function of dietary fiber is to adsorb more bile acid metabolites, allowing them to be excreted rather than recycled. In this way, the liver "has to" utilize more cholesterol to synthesize cholic acid to supplement the loss of cholic acid. Numerous studies have confirmed that increasing dietary fiber intake has a clear effect on lowering cholesterol.
4. The monounsaturated fatty acids contained in olive oil, tea oil, corn oil, and rapeseed oil have the effect of reducing low-density lipoprotein cholesterol (LDL-C). Can be paired with vegetable oils such as soybean oil and peanut oil in daily diet
5. Fish oil and lecithin have the effect of reducing blood lipids, but their effect is mainly aimed at the increase of triglycerides, and the effect of lowering cholesterol is relatively small (of course, it is still useful)
6. Components with antioxidant properties such as vitamin C and vitamin E may not directly reduce cholesterol in the blood, but they can help reduce the harm of cholesterol to blood vessels.
Source release pathway:
Cholesterol is the most abundant steroid compound in the body, serving as a component of cell biofilms and a precursor of steroid hormones, bile acids, and vitamin D. Therefore, for most tissues, ensuring the supply of cholesterol and maintaining its metabolic balance is crucial.
Cholesterol is widely present in various tissues throughout the body, with about 1/4 of it distributed in the brain and neural tissues, accounting for about 2% of the total weight of brain tissue. The liver, kidneys, intestines and other internal organs, as well as skin and adipose tissue, also contain a large amount of cholesterol, with approximately 200-500mg per 100g of tissue. The liver is the most abundant, while muscles are less abundant. The cholesterol content in tissues such as the adrenal gland and ovaries can reach as high as 1% -5%, but the total amount is very small.
The source of sterols in the human body relies on synthesis in the body and intake from food. Normal people's daily diet contains about 300-500mg of cholesterol, mainly from animal organs, egg yolks, cream, and meat. Plant based foods do not contain cholesterol, but contain plant sterols such as B-sitosterol and ergosterol, which are not easily absorbed by the human body. Excessive intake can also inhibit the absorption of cholesterol.
Cholesterol conversion:
Cholesterol is not completely oxidized and decomposed into CO, H, O in the body, but undergoes oxidation and reduction to transform into other compounds containing cycloalkane tetrahydrophenanthrene mother nuclei. Most of them further participate in internal metabolism or are excreted from the body.
Cholesterol can serve as an important component of cell membranes in the body. In addition, it can also be transformed into various substances with important physiological effects, such as adrenal cortical hormones in the adrenal cortex and sex hormones in the gonads, such as androgens, progesterone, and progesterone; In the skin, cholesterol can be oxidized to 7-dehydrocholesterol, which is often converted into vitamin D3 by ultraviolet radiation; In the liver, cholesterol can be oxidized into bile acids, promoting the digestion and absorption of lipids.
Cholesterol is oxidized in the liver to produce bile acids, which are excreted with bile and account for approximately 40% of sterol synthesis per day. In the lower segment of the small intestine, most bile acids are reabsorbed into the liver through the hepatic circulation, forming the hepatointestinal circulation of bile. A small portion of bile acids are excreted from the body through the action of intestinal bacteria. Drugs such as Xiaobilian can bind with bile acids, block the intestinal hepatic circulation of bile acids, increase the excretion of bile acids, and indirectly promote the transformation of cholesterol into bile acids in the liver. The liver can also directly discharge cholesterol into the intestine, or through the shedding of the intestinal mucosa, it can be discharged into the intestinal cavity; Cholesterol can also be reduced by intestinal bacteria to fecal sterols and excreted from the body.