Answer : We posed this question to Helen Rasmussen, PhD, RD, senior research dietitian at Tufts Jean Mayer USDA Human Nutrition Research Center on Aging. It turns out that the effect of microwave cooking on the nutritional value of food is an intriguing question-so much so that Rasmussen put one of her students on the case, Emily Evans, a master of science candidate at Tufts Friedman School. Microwaving is usually faster than other cooking methods, Evans points out, and may actually have some advantages when it comes to preserving nutrients. For one thing, microwaving uses less water than boiling, and foods cooked in water lose more nutrients than those cooked without. Microwave ovens also typically use less heat than other cooking methods, making them less destructive. Water-soluble vitamins such as vitamins B, C and folic acid are very heatsensitive. Recent studies at Cornell University found that spinach cooked in the microwave kept most of its folic acid, but lost about 77% when cooked on the stove.
The bottom line, according to Evans:Microwave cooking does not cause significant loss of human health-related nutrients in foods, as long as the amount of water used and cooking time are limited.