Mineral Preservation
Kyoto University researchers conducted a study on cooking's influence on mineral content. Their results, published in the "Journal of Nutritional Science and Vitaminology," found many minerals are lost during cooking. Monitoring potassium, sodium, calcium, magnesium, phosphorus, iron, zinc, manganese and copper levels, they found that cooking decreased mineral content by an average of 60 percent to 70 percent. Squeezing the vegetables after boiling incurred the biggest losses. Parching, frying and stewing the vegetables resulted in the fewer losses.