Purple sweet potato is rich in selenium and anthocyanins. Selenium is an anticancer substance, and anthocyanin is an organic active antioxidant, which can fight cancer and prevent aging. Special functions of anthocyanins:

Anthocyanins are widely found in the tissues of purple sweet potato, grape, blood orange, red cabbage, blueberry, eggplant skin, cherry, red orange, cranberry, strawberry, mulberry, hawthorn skin, perilla, black (red) rice, morning glory and other plants.

Anthocyanin brings many benefits to human body. Fundamentally speaking, anthocyanin is a powerful antioxidant, which can protect the human body from a harmful substance called free radicals. Anthocyanins can also enhance blood vessel elasticity, improve circulatory system and skin smoothness, inhibit inflammation and allergy, and improve joint flexibility. Some functions of anthocyanins are listed as follows:

1. helps to prevent many diseases related to free radicals, including cancer, heart disease, premature aging and arthritis;

2. Reduce the occurrence of heart disease and stroke by preventing platelet aggregation caused by stress reaction and smoking;

3. Enhance the immune system to resist carcinogens;

4. Reduce the number of colds and shorten the duration;

5. It has antimutagenic effect, thus reducing the formation of carcinogenic factors;

6. It has anti-inflammatory effect, so it can prevent inflammation including arthritis and swelling;

7. Alleviate pollinosis and other allergies;

8. Enhance the elasticity of arteries, veins and capillaries;

9. Protect the inner wall of arterial blood vessels;

10. Maintain the normal elasticity of blood cells, help red blood cells pass through tiny capillaries, thus enhancing blood circulation throughout the body, bringing direct benefits to organs and systems in various parts of the body and enhancing cell vitality;

1 1. Relaxation of blood vessels promotes blood flow and prevents hypertension (antihypertensive effect);

13. Prevent the hypertension caused by angiotensin converting enzyme released by the kidney (another hypotensive effect);

14. As a barrier to protect brain cells, prevent the formation of amyloid β protein, glutamate toxicity and free radical attack, thus preventing Alzheimer's disease;

15. By inhibiting elastase and collagenase, the skin becomes smooth and elastic, and the skin is prevented from being damaged by excessive sun exposure from both inside and outside.

Sweet potato, also known as sweet potato, sweet potato, sweet potato and so on. Sweet potato contains many nutrients needed by human body. Every 500 grams of sweet potato can generate about 635 kilocalories, including protein 1/kloc-0.5 grams, sugar 14.5 grams, fat1gram, phosphorus 100 mg, calcium 90 mg, iron 2 g and carotene 0.5 mg.

The contents of vitamin B 1 and B2 are 6 times and 3 times higher than those of rice, respectively. In particular, sweet potatoes are rich in lysine, while rice and flour just lack lysine. But many people haven't realized it yet.

Whether eating sweet potatoes can make people fat. According to scientific research, eating sweet potatoes will not make people fat. On the contrary, sweet potato is an ideal diet food.

Its calories are very low, much lower than ordinary rice. You don't have to worry about getting fat after eating it, but you can lose weight. Sweet potato also contains a substance similar to estrogen, which has a certain effect on protecting human skin and delaying aging.

So many foreign women regard sweet potato as beauty food. Sweet potato is crisp and sweet when eaten raw, which can replace fruit; Cooked food is sweet and soft. Eating it in your mouth is sweet in your heart. It can be used as both staple food and vegetable. There are many methods of steaming, boiling, frying and frying. Once cooked skillfully, it can also become delicious on the table.

(2) The health function of sweet potato:

■ Sweet potato has anticancer effect.

The most anticancer nutrients in the diet are β -carotene (the precursor of vitamin A), vitamin C and folic acid, and the contents of the three are rich in sweet potatoes. A small sweet potato (about 2 times) can provide twice the daily vitamin A, one third of the daily vitamin C, and about 50 micrograms of folic acid. The content of dietary fiber is higher than a bowl of oatmeal.

The antioxidant effects of β -carotene and vitamin C are helpful to resist the damage of oxidative stress to genetic material deoxyribonucleic acid (DNA) and play a certain anti-cancer role.

Eating sweet potatoes regularly helps to maintain the normal folic acid level of the human body, and low folic acid content in the body will increase the risk of cancer. Sweet potato has high dietary fiber content, which can promote gastrointestinal peristalsis and prevent constipation and colorectal cancer.

■ Sweet potato is good for the heart.

Sweet potato is rich in potassium, beta-carotene, folic acid, vitamin C and vitamin B6, all of which help to prevent cardiovascular diseases. Potassium contributes to the balance of liquid and electrolyte in human cells and maintains normal blood pressure and heart function.

β -carotene and vitamin C have the effects of anti-lipid oxidation and prevention of atherosclerosis. Supplementation of folic acid and vitamin B6 is helpful to reduce the level of homocysteine in blood, which can damage arterial blood vessels and is an independent risk factor for cardiovascular disease.

■ Sweet potato prevents emphysema

An animal experiment at the University of Kansas in the United States found that the level of vitamin A in smoking rats was low and emphysema was easy to occur. However, the incidence of emphysema in smoking rats fed with foods rich in vitamin A decreased significantly.

Why some long-term smokers live to be over 90 years old without suffering from emphysema may be related to the rich vitamin A content in their daily diet. Researchers suggest that smokers or passive smokers should eat some foods rich in vitamin A every day, such as sweet potatoes, to prevent emphysema.

■ Sweet potato has anti-diabetic effect.

Japanese researchers found that the blood insulin level of diabetic obese rats decreased by 26% and 60% respectively after eating white sweet potato for 4 weeks and 6 weeks. It is found that sweet potato can effectively inhibit the increase of blood sugar level in diabetic obese rats after oral glucose. Eating sweet potato can also reduce the levels of triglycerides and free fatty acids in diabetic rats.

It is suggested that sweet potato with white skin has certain anti-diabetic effect. A clinical study at the University of Vienna in Austria found that insulin sensitivity of patients with type 2 diabetes mellitus was improved after taking sweet potato extract, which helps to control blood sugar.

Sweet potato has always been regarded by nutritionists as a balanced food with the same origin of medicine and food. Its calories are only one-third of that produced by the same weight of rice, and it contains almost no fat and cholesterol. Eating sweet potatoes regularly is beneficial to human health and has a certain weight loss effect. But don't eat too many sweet potatoes at a time to avoid abdominal discomfort such as heartburn, acid reflux or bloating.

Sweet potato not only has high nutritional value, but also tender stems and leaves are nutritious fresh vegetables. The protein content of sweet potato stems and leaves is 10 times higher than that of spinach, spinach and other vegetables, and the contents of vitamin C, vitamin B2, calcium, iron and magnesium are higher than that of ordinary vegetables. How to eat the tip of the stem: stir-fry, stir-fry with meat, stew chicken or blanch it with boiling water and then cold mix, which tastes better than beans and celery. In Hong Kong and Guangzhou, dishes are called longevity dishes, Japanese Sichuan dishes and health tips. Especially for diabetics.