What effects on food and nutrients while use microwave?

Any form of cooking will destroy some nutrients in food, but the key variables are how much water is used in the cooking, how long the food is cooked, and at what temperature.Microwave ovens do convert vitamin B12 from the active to inactive form, making approximately 30-40% of the B12 contained in foods unusable by mammals.

Spinach retains nearly all its folate when cooked in a microwave; in comparison, it loses about 77 percent when cooked on a stove, because food on a stove is typically boiled, leaching out nutrients. Steamed vegetables tend to maintain more nutrients when cooked on a stovetop than in a microwave. Bacon cooked by microwave has significantly lower levels of carcinogenic nitrosamines than conventionally cooked bacon