Recent international research indicates that steaming and boiling are far superior to frying, deep-frying, or smoking. While the latter methods may yield more appealing color, aroma, and flavor, their destruction of nutrients is significant. Experts therefore recommend prioritizing low-temperature steaming and boiling for food preparation.
Experts note that steaming rice, wheat flour, and cornmeal preserves over 95% of their nutrients. In contrast, frying causes approximately 50% loss of vitamin B2 and niacin, while vitamin B1 is nearly entirely depleted.Eggs are a commonly consumed, nutrient-rich food. Their nutritional retention and digestibility vary significantly by cooking method. Boiled eggs maintain 100% nutritional value and digestibility, while steamed eggs retain 98.5%. Fried eggs, however, have a digestibility rate of only 81%. Thus, steaming or boiling eggs is optimal for both nutrition and ease of digestion.Take peanuts as another example. Peanuts are highly nutritious, especially the red skin covering the kernels, which inhibits fibrinolysis and promotes bone marrow's production of platelets. This provides effective hemostatic effects for various hemorrhagic diseases. Only by boiling peanuts can their nutritional components and health benefits be preserved. When fried, although they become crispy and flavorful, nearly half of their nutrients are lost.
One way cooking methods like frying destroy nutrients is by causing iodine in salt to evaporate, resulting in a discrepancy between the iodine content in iodized salt and the amount actually consumed. This occurs because frying requires high oil temperatures, around 180°C (356°F).Iodine is a chemically reactive element that readily volatilizes at high temperatures. Consequently, iodized salt subjected to frying can lose 40%-50% of its iodine content. Therefore, without altering cooking habits, even widespread promotion of iodized salt may fail to ensure adequate iodine intake.
Furthermore, frying and grilling not only degrade nutrients but also generate various harmful substances. At temperatures between 180°C and 300°C, foods undergo significant changes:Protein-rich foods produce carcinogenic heterocyclic amines; fats yield benzopyrene carcinogens and products from the cyclization, polymerization, and oxidation of unsaturated fatty acids; carbohydrate-based foods generate significant amounts of acrylamide compounds, which are also potential carcinogens.Scientific research confirms that higher cooking temperatures produce more carcinogens, which are also harder for the body to digest, absorb, and metabolize. Low-temperature cooking methods like steaming, boiling, and stewing are the healthiest for the human body.Since processing temperatures around 100°C do not generate harmful substances, we should strongly advocate using steaming and boiling methods for cooking while avoiding high-temperature techniques. This not only reduces the risks from carcinogens but also aids digestion and absorption. Particularly for children, the elderly, and those with weakened immune systems and detoxification capabilities, extra caution is needed to prevent harmful factors in food.