Green leafy vegetables are recognized as a healthy food, and the darker the color, the higher the nutritional value. Among the many leafy greens, which vegetables are more nutritious?
Experts interviewed
Fan Zhihong, Professor, College of Food Science and Nutritional Engineering, China Agricultural University
China Registered Dietitian Gu Chuanling
12 health benefits of leafy greens
The benefits of green vegetables have been proven in many studies at home and abroad, and can be summarized in the following 12 aspects:
Prevention of osteoporosis
Sufficient supply of potassium and magnesium in leafy greens can reduce calcium loss, and vitamin K is necessary for calcium deposition on collagen.
Protect eyesight
Provides high amounts of carotene and lutein, both of which are good for eye health and eyesight.
Vitamin supplementation
Not only can it provide quite a lot of vitamin B2, but vitamin C is also abundant.
Beneficial in preventing birth malformations
Leafy greens are the most important source of folate in the diet. Folic acid deficiency is associated with an increased risk of birth malformations.
Control your weight
The dietary fiber content is high, and eating half a kilogram of green leafy vegetables cooked with less oil in a meal can effectively increase satiety, delay the emptying rate of food in the stomach, and help control food intake.
Reduces the risk of diabetes
Studies have proved that when eating the same number of staple foods in a meal, increasing the intake of green leafy vegetables can delay the rise of blood sugar after meals.
Several epidemiological studies have proved that a high intake of leafy green vegetables reduces the risk of diabetes.
Prevention and control of high blood pressure
It can provide a large amount of potassium, calcium, and magnesium for the diet, and they can all resist the vasopressor effect of sodium to a certain extent.
Reduces the risk of coronary heart disease
More intake of vegetables is beneficial to reduce the body's inflammatory response and reduce the risk of coronary heart disease. Epidemiological studies have proved that people who eat more vegetables have a lower mortality rate from cardiovascular disease, especially ischemic heart disease.
Prevents many types of cancer
Epidemiological studies have shown that increased vegetable intake reduces the risk of a variety of cancers, including esophageal, stomach, lung, breast, and prostate cancers.
Prevents cognitive deterioration
Studies have confirmed that among fruits and vegetables, the most beneficial food to prevent cognitive deterioration is dark green leafy vegetables.
Improves athletic capacity
Dark green leafy vegetables are rich in nitrates, and nitrates themselves are non-toxic, which slowly transform into nitric oxide after being ingested by the human body, which plays a role in expanding blood vessels, improving blood circulation, and increasing the maximum oxygen consumption of athletes and improving exercise capacity.
Fight pollution
Studies have proved that chlorophyll, dietary fiber and a variety of phytochemicals in green leafy vegetables are beneficial to reduce the absorption of pollutants, promote their excretion from the intestine, improve the liver's detoxification ability, and reduce the mutagenic effect of carcinogens.
6 kinds of green vegetables are the "all-round king" of nutrition
There are more than 20 kinds of common dark green leafy vegetables, through the analysis of relevant nutritional data, Chinese registered dietitian Gu Chuanling screened out the most comprehensive nutrition of 6 kinds, and it is recommended to eat at least 2 fists (about 200 grams) a day.
Nutrition experts said that it is especially recommended that women often eat such vegetables for the following reasons:
1
Helps replenish calcium
According to the "Report on Nutrition and Chronic Diseases of Chinese Residents (2020)", the prevalence of osteoporosis in China is 4.4% in men over 40 years old, but as high as 20.9% in women. Therefore, women should supplement calcium well from a young age to increase the accumulation of bone mass.
Green leafy vegetables are a very good source of calcium, not only rich in calcium, but also rich in vitamin K, which promotes calcium deposition on bones.
2
High in vitamin C
Blood replenishment is an important part of women's health, and blood supplementation is inseparable from iron supplementation. Women from adulthood to menopause need 20 mg of iron per day, pregnancy and lactation need 25~35 mg, and men only need 15 mg per day. The trivalent iron in plant foods cannot be directly absorbed by the body, and vitamin C can convert it into divalent iron that can be directly absorbed.
3
Rich in antioxidants
In addition to vitamin C, green leafy vegetables are also rich in β carotene, α tocopherols, lutein, zeaxanthin, which combine to better resist oxidation and anti-inflammatory.
4
Rich in isothiocyanate
Green leafy vegetables such as broccoli, kale, rape, Chinese cabbage, mustard greens belong to the cruciferous family, and these vegetables are rich in isothiocyanates. Isothiocyanate and its metabolites can promote the conversion of estrogen to 2-hydroxyestrone, thereby weakening estrogen-induced proliferation and carcinogenesis of breast cells.
5
Rich in folic acid
For rapidly developing embryonic cells, DNA synthesis is faster and most sensitive to folate deficiency. Therefore, women who are trying to get pregnant and pregnant should pay attention to supplementing folic acid, and green leafy vegetables are the most important dietary source.
A guide to healthy intake of leafy greens
Eating more leafy greens has benefits, and if combined with the right intake method, it can maximize the benefits.
Guaranteed intake
The "Dietary Guidelines for Chinese Residents (2022)" recommends that fresh vegetables should be consumed every day, with a total amount of 300~500 grams, which is about equal to the amount of vegetables held in two hands, of which dark vegetables should account for more than half.
Master the correct cooking method
Some leafy greens, such as spinach and amaranth, contain higher oxalic acid, which will affect the absorption of magnesium, and it is recommended to blanch vegetables with boiling water before stir-frying.
Pay attention to the best "eat" time
Green leafy vegetables are the most prone to wilting and loss of vitamins, and storage at room temperature increases nitrite content, so it is best to eat within 3 days.
Use appropriate storage methods
It is recommended to wrap the green leafy vegetables in soft paper, put them in a food plastic bag and put them in the refrigerator, taking care not to be close to the inner wall of the refrigerator to avoid frostbite.
After cooking, it can not be placed at room temperature, if a meal cannot be finished, be sure to put it in the refrigerator in time to inhibit the proliferation of bacteria. ▲
Editor of this issue: Deng Yu