For a long time, it has been widely believed that eating raw vegetables is beneficial to health. The reason for this is easy to understand: eating vegetables raw does not lead to a loss of nutrients, and it best preserves their beneficial components and active substances. However, is cooked vegetables completely undesirable?
According to a recent report in The New York Times, research shows that when it comes to eating vegetables, the key is not how much you eat, but how you eat it, because it determines how many phytochemicals, vitamins, and other nutrients can be absorbed by the human body. A research report in the latest issue of the British Journal of Nutrition points out that people who consistently eat raw vegetables generally have lower-than-average levels of lycopene in their blood. (Lycopene is a carotenoid found in red vegetables like tomatoes and is also one of the most potent antioxidants.) A recent research report published in the American Journal of Agricultural and Chemistry also indicates that for carrots, zucchini, and broccoli, cooking them is more nutritious than frying or eating them raw.
Associate Professor He Jiguo from the Department of Nutrition and Food Hygiene at the College of Food Science and Engineering at China Agricultural University said: "There is a misconception that all foods are best eaten raw. For vegetables and fruits, in many cases, light cooking or processing may be more beneficial to the human body." Minerals such as potassium, calcium, and magnesium in vegetables are not destroyed by heat. The loss rates of vitamins B2, K, and carotenoids during cooking are also low, and dietary fiber is not lost. The only nutrients with significant losses are vitamin C and folic acid.
He Jiguo pointed out that cooking can improve the absorption and utilization of vitamin K and carotenoids in green-leafy and orange-yellow vegetables. These fat-soluble nutrients are not water-soluble and only dissolve in fats and oils. The thick cell walls of vegetables break down and soften during cooking, increasing the permeability of the biological membrane and promoting the dissolution of nutrients such as carotenoids and lycopene from the cells, which can effectively increase the absorption rate. Even without stir-frying with oil, simply cooking them in water that contains some fat, or blanching them and then tossing with oil, can achieve this effect. A more ideal approach is to eat most dark-colored vegetables cooked and lighter, crisp, and tender vegetables raw. The cooking temperature for vegetables should be kept as low as possible, and the cooking methods should be light and low in oil.