The New York Times website recently reported that research shows that when it comes to eating vegetables, the key is not how much you eat, but how you eat them, as this affects how many phytochemicals, vitamins, and other nutrients the body can absorb.
A research report to be published next month in the British Journal of Nutrition details a follow-up study of 198 Germans who strictly adhere to a raw-food diet. The results found that their vitamin A levels were the same as the average person's, while their beta-carotene levels were relatively higher.
However, they were generally deficient in lycopene. Lycopene is a carotenoid found in red vegetables like tomatoes and is one of the most potent antioxidants. Among the 198 Germans who ate their vegetables raw, nearly 80% had blood lycopene levels below the average.
Steven Clinton, a professor of internal medicine in the Division of Medical Oncology at Ohio State University and a researcher in nutrition, said: "There is a misconception that all foods are best eaten raw. For vegetables and fruits, in many cases, light cooking or processing can be more beneficial to the human body."
Fat-soluble nutrients such as vitamins A, D, E, K, and antioxidant compounds like carotenoids do not dissolve in water. The thick cell walls of plants break down during cooking, releasing components that the body can absorb. Therefore, processed tomato products have a higher lycopene content than fresh tomatoes.
A recent research report published in the Journal of Agricultural and Food Chemistry指出 that for carrots, zucchini, and broccoli, boiling is more nutritious than steaming, frying, or eating them raw, with frying being the least desirable method.
What you eat them with is also important. Researchers at Ohio State University found that adding a high-fat avocado or a full-fat dressing to a vegetable salad increased the absorption of lycopene, lutein, and beta-carotene by 4, 7, and 18 times, respectively.
Different cooking and preparation methods result in vastly different nutritional values and flavors for vegetables. Therefore, the most important thing is to use different methods to eat different vegetables.