Despite what you might read on the Internet, microwaving your food does not “kill” nutrients. In fact, it can make certain nutrients more available to your body. In terms of the impact on your food’s nutrients, microwaving is the equivalent of sautéing or heating up in a pan (just a lot more convenient).
Research on this topic shows that whenever you cook greens (broccoli, spinach, etc), some of the B vitamins and other water-soluble vitamins are lost. The amount you lose depends on the duration and rigor in which the food is cooked—steaming broccoli in the microwave for 90 seconds is a lot different than nuking it for five minutes. Another example: Sautéing green beans in a pan allows for much better vitamin retention than if you were to boil them.
Boiling leaches the most nutritients out of your food, so with the exception of potatoes, try to avoid boiling your vegetables.
Although cooking vegetables does reduce the amount of certain vitamins, it can also liberate other nutrients, like antioxidants, allowing for greater absorption by the body. Research from the University of Oslo found that microwaving or steaming carrots, spinach, mushrooms, asparagus, broccoli, cabbage, green and red peppers, and tomatoes led to an increase in the antioxidant content of the foods (in that the antioxidants become more available for absorption).
And still more research shows that lycopene, the powerful antioxidant that gives tomatoes and watermelon their red color, is better absorbed by the body when it’s consumed in cooked or processed tomato products—salsa, spaghetti sauce, ketchup, etc.—rather than fresh tomatoes.
Eating cooked vegetables has its pros and cons, but the bottom line is that it’s important to eat your food in a variety of ways. Enjoy raw spinach in salads and go for wilted or steamed as a side dish with dinner.
If you use a microwave to steam your veggies, be careful not to add so much water that you’re actually boiling, and watch the clock to avoid overcooking (the amount of time needed will vary greatly, depending on the type of vegetable and how small it’s cut). The primary takeaway is to incorporate both raw and cooked foods into your diet. It’s the easiest way to ensure that you’re getting the maximum amount of vitamins, minerals, and antioxidants.
