Nutrition believes that the best diet is actually a balanced diet. The first principle of a balanced diet requires that foods be as diverse as possible. One is variety, that is, try to eat all kinds of food, such as grain, meat, beans, milk, eggs, vegetables, fruits, oil, fat and so on; The other is the diversity of species, that is, we should try to eat all kinds of food, such as pork, beef, mutton, chicken, fish, rabbits, ducks and so on. The same is true of grain. Eating only polished rice and white flour and coarse grains, such as millet, corn, buckwheat, sorghum and oats, is not in line with the principle of dietary balance. There is an understanding of this ancient book of Chinese medicine, Huangdi Neijing, which says that "five grains are the supplement, five fruits are the help, five animals are the benefit, and five dishes are the supplement". Among the five grains, rice and wheat are generally considered to belong to flour and rice; Coarse grains refer to other grains except rice and wheat, that is, corn, buckwheat, oats, millet, sorghum and potatoes mentioned above. Some trace elements in miscellaneous grains, such as iron, magnesium, zinc and selenium, are more than those in flour and rice. These trace elements are of great value to human health. The contents of potassium, calcium, vitamin E, folic acid and bioflavonoids in coarse grains are also richer than those in flour and rice. Coarse grains are good for diabetes. Replacing some flour and rice with coarse grains is good for diabetic patients to control blood sugar. Recent studies show that the postprandial blood sugar changes after eating coarse grains and miscellaneous beans are generally less than those of wheat and ordinary rice, which is beneficial to control blood sugar in diabetic patients. At present, some foreign diabetic dietary guidance organizations suggest that diabetic patients should try to choose coarse grains and miscellaneous beans, which can be eaten as staple food or part of staple food. But the ability of these coarse grains and miscellaneous beans to maintain postprandial blood glucose response is also different. Such as oat, buckwheat, barley, Redmi, black rice, adzuki bean and lentil, can obviously relieve postprandial hyperglycemia of diabetic patients, reduce blood sugar fluctuation within 24 hours, and reduce fasting blood sugar and insulin secretion, which is beneficial to blood sugar control of diabetic patients. Coarse grains help to lower blood pressure ① Buckwheat: The difference is that buckwheat contains "rutin", which can lower cholesterol in human blood and protect blood vessels. Nepalese at the southern foot of the Himalayas. Not only eat a lot of buckwheat noodles, but also eat tender stems and leaves of buckwheat, while local residents rarely suffer from hypertension. ② Oats: In recent years, linoleic acid has been found in oats, and the linoleic acid in 50g oats is equivalent to 10 "Maitong", so oats can inhibit the increase of cholesterol. It is reported that a related study in the United States confirmed that eating 60 grams of oats every day can reduce cholesterol by an average of 3%. British research shows that drinking a bowl of oatmeal every morning can reduce the death rate of heart disease by 6%. Many enzymes contained in oatmeal have strong vitality and help to delay cell aging. ③ Corn: Corn contains more linoleic acid, multivitamins, cellulose and various minerals, especially magnesium and selenium, which has comprehensive health care functions. In recent years, it has been found that corn contains a longevity factor-glutathione, which can produce glutathione oxidase with the participation of selenium, and has anti-aging and anti-aging effects. ④ Soybean: Experiments have proved that soybean and its products have special effects on cardiovascular system. Regular consumption of soybean food can effectively reduce serum cholesterol and help reduce the damage of arterial wall. Some scholars have found that soybeans soaked in vinegar can be used to treat hypertension and obesity. Because the saponin in soybean can eliminate the fat attached to the blood vessel wall and reduce the cholesterol content in blood. ⑤ Sweet potato: Professor Schwartz of the United States found that there are estrogen-like substances in sweet potato, which have a certain effect on keeping skin delicate and delaying cell aging. Japanese medical experts reported that mucin in sweet potato is a mixture of polysaccharide and protein, which belongs to collagen and mucopolysaccharide. It can relieve fatigue, improve human immunity, promote cholesterol excretion, maintain arterial elasticity and prevent arteriosclerosis, thus reducing the occurrence of cardiovascular diseases such as hypertension. Eating fresh sweet potato can also reduce plasma lipid concentration, which is beneficial to prevent hyperlipidemia and arteriosclerosis. Eating coarse grains regularly can prevent stroke. A 12-year study in the United States shows that eating a lot of whole grains (coarse grains) can significantly reduce the risk of stroke. 1984- 1996, Harvard University in the United States conducted a health survey on more than 70,000 nurses aged 38-63. These nurses did not suffer from diabetes, coronary heart disease, stroke or other cardiovascular diseases before the survey. "Nurses' Health Survey" is to study the relationship between women's diet patterns and lifestyles and chronic diseases. Participants assessed their diet through an email questionnaire. The food frequency questionnaire includes more than 100 kinds of foods, and respondents fill in the number and quantity of these foods eaten every day in the past few days. Whole grain foods (coarse grains) include brown bread, whole grain breakfast, fried corn, oatmeal, malt, brown rice, bran and so on. Noodles and rice foods include sweet rolls, cakes, desserts, white bread, fruit pies, English muffins, biscuits, white rice, pancakes, waffles and so on. It also includes the consumption frequency of saturated fatty acids and trans fatty acids related to cardiovascular diseases. Conduct regular questionnaire surveys. In order to reduce the changes between people and between days, the data are processed by cumulative average method, which can clearly identify the participants' eating patterns. In order to understand the relationship between coarse grains and stroke more accurately, lifestyle factors related to stroke, such as smoking, drinking, exercise and hormone use after menopause, were also considered. Whether the respondents had suffered from stroke during the investigation period was judged and classified according to their medical records and the standards recommended by the national stroke review.