Colorectal Medicine
Nutrition, food and cancer are inextricably linked and play an important role in the process of cancer occurrence. Among them, there is no tumor more closely related to diet than gastrointestinal tract tumors, such as gastric cancer, esophageal cancer, liver cancer and colon and rectal cancer, followed by breast cancer.
I. Carbohydrates
Carbohydrates, also known as sugars, are the main source of heat energy for human body. After it is digested in the body, it is mainly absorbed and utilized in the form of glucose. Glucose can be rapidly oxidized and provide (release) energy. Studies by foreign scholars have found an association between the amount of refined sugar consumed and the incidence of breast cancer. The mortality rate of gastric cancer is positively correlated with the intake of grains. However, stomach cancer is actually high in countries that do not have high starch as the main diet.
Dietary fiber
It is generally believed that dietary fiber is negatively correlated with tumor, and the intake of cereals, vegetables and fruits are the main dietary substances. 2001 European Symposium on Nutrition and Cancer held in Lyon, France, experts unanimously emphasized the role of dietary fiber in cancer prevention, and the results of a survey of 400,000 people in 9 countries showed that increasing the fiber content in food can reduce the risk of colorectal cancer (colon and rectal cancer) by 40%. In other words, consuming a high fiber diet can reduce the incidence of breast cancer.
Food fiber is divided into two categories: soluble and insoluble. Insoluble dietary fiber is mainly a component of plant cell wall, which is insoluble in water and can absorb water to soften stool so that harmful substances in stool are not easily contacted with intestinal wall; soluble fiber forms mucilage with glucose after meeting water in gastrointestinal tract and combines with bile acids to reduce the carcinogenic effect of toxic bile acids. Both soluble and insoluble dietary fiber can increase stool volume and increase the number of beneficial bacteria in the intestine, all of which have anti-cancer effects. Bran has been shown to reduce the carcinogenic effects of certain chemicals, and fiber plays a protective role against chemical-induced tumors.
Insoluble food fiber includes cellulose, hemicellulose, essentiin and chitin, which are found in the outer skin of cereals, beans, stems and leaves of plants, as well as shrimp and crab shells. The main raw material of “gluten” in the Chinese diet is bran, which is rich in plant fiber, and other staple foods of the Eastern people, such as corn and soybeans, and commonly eaten fruits such as coconut and olives, all contain more than 5 grams of fiber per 100 grams. The U.S. Institute of Medicine recommends that adults consume 38 grams of dietary fiber per day for men and 25 grams for women. Based on this amount, each person should eat at least 4 kg of vegetables per day. This is practically impossible, so you should know which foods contain more fiber, diversify food, coarse and fine, and try to use foods that contain more fiber to purposefully increase the amount of fiber intake in the diet.
Among the food fibers, it is worth mentioning chitin. This substance is found in the shells of crabs, lobsters and shellfish, and has various physiological functions. In recent years, it has been found that chitin, especially its polysaccharide component chitosan, has anti-cancer effects, which are manifested in.
①Killing cancer cells directly. Transplanting cancer cells to mice to give birth to skin cancer, and then dividing them into two groups, with one group given chitosan and the other group not, resulting in the disappearance of cancer in the former group and the death of all in the latter.
② Inhibiting toxins released from cancer cells, increasing appetite and improving anemia.
(iii) Activate lymphocytes and enhance immune function. Lymphocytes in human body can kill cancer cells, and their effect is most active in pH 7.4 environment. Chitosan can increase the pH in the body, thus providing good conditions for lymphocytes to kill cancer cells.
④Block tumor blood vessel neovascularization and inhibit cancer cell metastasis. Cancer cells must pass through blood vessels to metastasize. There is a kind of adhesion molecule on the surface of blood vessel wall, and cancer cells firstly attach and bind with this molecule, and then transfer to other places through blood vessels. Chitosan can compete with the adhesion molecule, thus preventing cancer cells from binding with the adhesion molecule, which means reducing the metastasis of cancer cells.
⑤ Chitosan has a laxative effect and prevents colon and rectal cancer.
Three, fat
Excessive intake of animal saturated fat will cause hyperlipidemia, leading to atherosclerotic heart and cerebrovascular disease. In order to reduce blood lipids, some people advocate the use of polyunsaturated fat instead of saturated fat. However, fats, especially polyunsaturated fats, are closely related to a more vicious disease, cancer. Numerous clinical observations have shown that fats have a role in inducing carcinogenesis. At low fat intake levels, the carcinogenic effect of unsaturated fats is greater than that of saturated fats; at high fat intake levels, the carcinogenic effect of both is the same.
According to clinical analysis, among all dietary factors, the relationship between fat and tumors is one of the most direct, clear and strongest factors, which is mainly related to intestinal tumors and endocrine organ tumors, especially to breast, prostate and colon cancers. Studies across 40 countries clearly show us that there are many nationalities in the world where the incidence of breast, prostate and colon cancer is very low, while the opposite is true in Western countries such as Europe and the United States. These three cancers are rare in areas where the diet is low in fat, and this is also true for ovarian and uterine cancers. Once people discontinue low-fat diets in favor of high-fat, the incidence of these cancers rises. Dr. Berg of Iowa University pointed out that the incidence of breast cancer in countries with high fat consumption is 5 to l0 times higher than in countries with low consumption. He also pointed out that animal fats are the main root cause of cancer, but polyunsaturated lipids have even greater cancer-promoting properties.
(I) Dietary fat and breast cancer
The relationship between dietary fat and breast cancer incidence has received increasing attention. In 1982, the American Life Science Federation, including the Committee on Nutrition and Cancer, recommended reducing fat intake to reduce the incidence of breast cancer. Enig et al. found that fat content in food was associated with breast cancer incidence and mortality. Animal studies have shown that the application of a high-fat diet to mice increases the incidence of breast cancer. A high-fat diet shortened the time of mammary cancer induction by “dimethyl pyreneanthrene” (a tumorigenic carcinogen) in mice, suggesting that fat plays a role in the pro-carcinogenic phase of mammary tumor formation. Weight gain in premenopausal women seems to have little relationship with the risk of breast cancer.
Current studies suggest that the mechanisms by which dietary fat affects the risk of breast cancer are mainly as follows.
1. dietary fat directly affects ovarian estrogen production and increases prolactin secretion, which in turn increases estrogen secretion through the thalamus-pituitary axis.
2. dietary fat can alter intestinal flora and convert steroids from bile to estrogen in the colon, and dietary fat can also increase the conversion of androstenedione to estrogen
3. Dietary fat is related to the composition and physical properties of cell membranes. Changes in cell membrane permeability will facilitate the entry of chemical carcinogens, and dietary fat also affects the metabolism of chemical carcinogens.
4. Dietary fat can affect the early age of menarche and the delayed age of menopause.
(2) Dietary fat and prostate cancer
In the past, it was always thought that the incidence of prostate cancer in western countries was much higher than that in developing countries because of race. Recent studies have shown that the incidence of prostate cancer is closely related to the type and amount of fat that people eat. Harvard Medical School surveyed 48,000 men and found no evidence that a high-fat diet was associated with the incidence of prostate cancer, but did find that a high-fat diet had a risk of promoting the development of this cancer. The Harvard Medical School researchers also noted that different lipids have different effects on the development of prostate cancer. Saturated fats, fish oils, and vegetable fats are not associated with tumor aggressiveness, while unsaturated fats can increase the risk of tumor spread. Thus, a diet rich in linoleic acid reduces the risk of pro-tumor spread by 40%, while a diet high in alpha-linolenic acid increases this risk twofold. Foods such as beef and lamb, cheese or chicken with skin can promote the spread of prostate cancer. Statistics show that people who eat more of these foods in the population are 2.5 times more likely to die from prostate cancer than those who eat less. On the contrary, chicken without skin and fat-free dairy products do not increase the risk of prostate cancer spread. The reason for this may be hormonal; fat stimulates the production of testosterone and three other hormones. The role of testosterone can accelerate the growth of prostate cancer. In theory, high levels of testosterone can stimulate dormant prostate cancer cells to enter the active phase; some data suggest that high levels of testosterone can also influence the initial development of prostate cancer.
(iii) Dietary fat and rectal cancer
A large amount of epidemiological data shows that high fat diet can significantly increase the incidence of colon and rectal cancer. The possible mechanism is that increased fat intake can promote the secretion of bile acids into the intestine, thus affecting the composition of the intestinal microflora, stimulating secondary bile acid production and promoting the development of colon cancer. In animal models, polyunsaturated fatty acids appear to have a higher risk for cancer development than saturated fatty acids, possibly through increased synthesis of eicosanoid compounds. Human experiments have demonstrated that primarily saturated fats are associated with an increased risk of cancer. This may be due to the fact that most people’s diets contain sufficient amounts of polyunsaturated fatty acids to have increased the risk of cancer development to the maximum, with saturated fatty acids only playing an additional role in promoting it.
(iv) Control of dietary fat
So, how to control the fat in the diet? The following aspects can help you to do so.
1, eat less red meat and more fish and poultry
2, choose lean meat, try to cut off all the fat visible to the eye, and eat poultry with the skin removed.
3.Eat less fried food and use more steaming, stewing, searing and baking instead.
4.Do not use a lot of oil for frying, use a small amount of oil or searing vegetables.
5.Avoid using bone or fatty meat in soup, if it is old fire soup or fatty soup, must skim oil before eating.
6.Use skim or low-fat milk.
7, try low-fat margarine, yogurt and cheese.
8. avoid or reduce eating at cafes and eat less greasy take-out food (e.g. fish and chips, hamburgers and sausages).
9. avoiding high-fat snacks such as potato chips and butter cookies.
10.Avoid excessive consumption of foods that are too festive, such as rice cakes, dumplings, oil horns and moon cakes, which contain a lot of fat.
IV. Protein
Protein is composed of many amino acids, if the proportion of amino acids is appropriate, then regardless of the high or low content of protein in the feed is not easy to make mice induced viral breast cancer, skin cancer and lung cancer caused by benzo(a)pyrene, hepatocellular carcinoma caused by trimethyl azobenzene, etc.. The results of epidemiological and animal experiments also show that if the dietary protein content is low, it can promote the development of tumors in humans and animals. If the protein content is increased, the occurrence of animal tumors can be inhibited. For example, it has been reported that the incidence of stomach cancer is higher in poor people than in rich people in capitalist countries. There are further investigations on the relationship between milk and gastric cancer incidence, and the relative risk of gastric cancer was 1.0, 0.77, 0.45 and 0.2 for those who did not drink milk, sometimes drank milk, drank 180 ml per day and drank more than 360 ml per day as four groups respectively. It is believed that this is related to the sufficient amount of tyrosine in milk. In China, the general population in areas with a high incidence of esophageal cancer has poor nutrition, and most people do not consume enough protein and calories. Supplementation with protein or certain amino acids can inhibit tumorigenesis. For example, when esophageal cancer was induced by methylimine in rats, the incubation period of esophageal cancer in animals of high protein group was prolonged, the incidence of esophageal squamous cell carcinoma was lower, and the cancer cells were better differentiated.
If the protein intake was increased to 2-3 times the normal requirement, the opposite was shown to enhance chemical-induced tumorigenesis. According to Dr. Redricks, Dean of International Preventive Medicine Research, when a person consumes more than 90 grams of protein daily, his body starts to increase the loss of calcium, phosphorus, iron, zinc, and magnesium, which are beneficial for maintaining good health (effective against cancer) and are directly related to cancer suppression; in addition, a high protein diet may promote the growth of malignant tumors in another way . In addition, it has been shown that protein also has the effect of making vitamin A loss antagonistic to the anticancer element magnesium. Excessive protein intake is obviously harmful to cancer prevention.
V. Vitamins
Most of the vitamins need to be supplemented from food. Vitamins are widely involved in metabolic functions in the body and have powerful antioxidant effects. At present, it is believed that the anti-cancer pathways of vitamins include: ① stopping the synthesis of carcinogenic nitrosamines in the body; ② deoxycholic acid is synthesized in the intestine and has carcinogenic effect, while vitamin C can inhibit deoxycholic acid synthesis; ③ interferon has the function of improving immune function and inhibiting cancer, and vitamin C can promote interferon synthesis; ④ promoting immunoglobulin synthesis and improving immune function; ⑤ promoting collagen synthesis and promoting collagen to surround cancerous (5) Promote collagen synthesis, promote collagen to surround cancer and prevent cancer from spreading.
(i) Vitamin C
Since the discovery of vitamin C for scurvy in the 1820s, vitamin C has been widely used and its anti-mutagenic and anti-cancer effects have been confirmed. Vitamin C is widely found in fresh fruits and vegetables. Vegetables and fruits containing more than 100 mg of vitamin C per 100 g include: fresh dates (243 mg), peppers (sharp and green) (185 mg), persimmon peppers (red) (159 mg), alfalfa (118 mg), etc. However, in terms of foods commonly consumed by humans, vegetables and fruits consumed daily are sufficient to provide adequate amounts of vitamin C.
The natural vitamin C present in vegetables and fruits combined with vitamin P is superior to synthetic vitamin C. There are various brands of vitamin C preparations on the market, and the following matters should be noted when taking them: ① Overdose can cause the formation of large amounts of oxalic acid crystals, which can lead to kidney stones, and can also cause diarrhea, headache, frequent urination, nausea, vomiting, stomach cramps and infertility; ② Adults need 100 mg of vitamin C daily, and can take 500 mg for a long time, up to 1000 mg; ③ Taken alone, such as with milk (3) taken alone, such as with milk will fail due to acid-base interaction; (4) gout, kidney stones patients should be careful with vitamin C, because it can aggravate the disease.
(B) Vitamin E
Vitamin E, also known as tocopherol, is a powerful natural antioxidant that can scavenge free radicals in the cell surroundings, inhibit nitrosamine production, enhance T-lymphocyte function, induce apoptosis of cancer cells, and have a direct inhibitory effect on certain cancer cells, such as prostate cancer cells. Vitamin E exists in various vegetable oils and hard fruits, such as soybean oil, sunflower oil, sesame oil, corn oil, peanut oil in vitamin E content per 100 grams of the median amount of 40 mg or more.
(iii) Vitamin B
Including vitamin B1, B2, PP, B6, as well as pantothenic acid, biotin, folic acid and vitamin B12, etc., in the body as coenzymes to play a role, such as human physiology and metabolism necessary, a serious lack of containing interference with the body’s function, and promote the development of cancer.
Vitamin B1 is a coenzyme of the enzymes required in sugar metabolism, and the more sugar foods are consumed, the more vitamin B1 is needed. Vitamin B1 deficiency can cause nervous system dysfunction. Foods rich in B1 include yeast, peas, peanuts, soybeans, and pork liver.
Vitamin B2 is the material necessary for the production of glutathione in the body, and this enzyme has the effect of making reactive oxygen species non-toxic, i.e. vitamin B2 has an indirect antioxidant effect. B2 is abundant in whole grain foods and wheat germ.
Vitamin B12 is also known as cobalamin, and vitamin B2 in natural foods is hydroxycobalamin. Vitamin B12 deficiency can cause impaired immunoglobulin production and reduced immunity, which facilitates cancer formation. In the normal human stomach, vitamin B12 forms a complex with internal factors, and this complex is stable and not easily destroyed. Foods containing vitamin B12 include shiitake mushrooms, soybeans, eggs, milk, animal kidneys and various fermented soy products.
(D) Vitamin A
Vitamin A has special health effects and enhances the body’s immunity against disease. As it can inhibit the formation of tumors in animals caused by chemical carcinogens, it has certain protective, preventive and inhibitory effects in controlling the differentiation of epithelial cells, protecting the soundness of mucous membrane and preventing the occurrence and development of cancer cells, especially for respiratory system and gastric cancer.