When selecting vegetables, it's important to pair them reasonably and cleverly. Adhering to a variety of types and colors is key to ensuring a balanced nutritional intake. The nutritional content and value of vegetables vary due to differences in their edible parts, color depth, growth stage, and even different parts of the same plant. Therefore, you can focus your selection based on your specific needs. Generally, vegetables can be divided into three main categories: leafy and stem, root, and fruit. Additionally, there are flower and gourd vegetables.
Leafy and Stem Vegetables
Examples include rape, chives, bok choy, and spinach. These are rich in Vitamin C and carotene. Spinach contains iron, but it also has oxalic acid, which can hinder the absorption of calcium and iron from other foods. Therefore, it should be briefly blanched in boiling water before cooking.
Root Vegetables
Examples include radish, carrot, taro, potato, and sweet potato. Radishes are very high in Vitamin C, carrots contain a large amount of carotene, while potatoes and taro are high in starch and calories but lower in other nutrients. A common characteristic of root vegetables is their rich dietary fiber. If radishes or carrots are sliced thinly or into strips and left for 1-2 days, their dietary fiber content can increase by about three times. Therefore, radishes and similar foods should be cut and eaten immediately; they are not suitable for storage after being cut.
Fruit Vegetables
Examples include tomatoes, beans, bell peppers, cucumbers, loofah, pumpkin, and eggplant. With the exception of beans, pumpkin, loofah, and eggplant, these vegetables are best eaten raw to avoid the destruction of vitamins during cooking. Tomatoes contain a good amount of lycopene and Vitamin C. Beans, including kidney beans, peas, and edamame, are high in protein and have a more complete amino acid profile than grains. They are also higher in calcium, phosphorus, iron, and Vitamin B1 compared to other vegetables. Pumpkin is very high in carotene, and peppers are rich in carotene and Vitamin C.
Different parts of the same vegetable plant can also have different nutritional values. For example, the green part of a scallion has a much higher nutritional content than the white part. The Vitamin A, B1, and C content in the white part is less than half of that in the green part. Similarly, in celery, the dark green leaves contain more Vitamin A and C than the lighter green stalks. The same is true for bok choy, where the leaves are more nutritious than the stems.
Since the human body requires "all-around" nutrition, it's impossible to meet this need by eating just one type of vegetable. Therefore, only by combining them reasonably and cleverly, and maintaining a variety of types and colors, can we ensure a balanced nutritional intake.