Do microwave ovens zap nutrients in food?

The other day, I received a message when I returned to my desk after a meeting. Someone had called to ask about microwave ovens and nutrition.

As I listened to the question, I decided that I was settling a bet. When people are making wagers about nutrition, I don't mind being involved.

The gentleman caller's friend had said that microwaving food destroyed the nutrients. He didn't agree, but he wanted proof in writing.

My first option was to go online to see what people were finding. Sure enough, lots of articles are out there that say that microwave ovens zap nutrients.

I pictured all the folate (a B vitamin) flying out of broccoli and being caught in a nutrient trap hidden in a microwave.

No, a nutrient trap doesn't exist on your microwave. I just made that up.

I found even scarier, unproven things about microwave ovens in my search, but I also found good information. As we know, we can't believe everything we read. Unfortunately, the amount of misinformation is escalating.

Then I consulted the "gold star" reference of truthful information: peer-reviewed journal articles. These articles provide factual, science-based information that we can trust. Our job in the Extension system is to translate the science so you can put it to use in your daily life.

In one study, a group of scientists in China studied the effect of various cooking methods on the nutrients in broccoli, including vitamin C and glucosinolates (the compounds linked to many health benefits in broccoli, including reducing the risk for cancer). The scientists cooked broccoli by steaming, boiling, stir-frying or microwaving, then they determined the methods that preserved the most nutrients by testing the nutrient content in their laboratories.

Microwaving wasn't the "best" method, but it wasn't the worst. Steaming (cooking in a small amount of water) preserved the most nutrients in broccoli, while boiling in water and stir-frying caused the greatest nutrient losses.

Other scientists have shown that microwave ovens have minimal effects on protein, fat and minerals in foods. Cornell University scientists reported that spinach cooked in a microwave oven retained almost all of its folate, but spinach lost nearly 80 percent of the folate when boiled in water on a stove.

Bottom line: To preserve the most nutrients, including vitamins, use as little liquid as possible and heat for the shortest amount of time. A microwave oven can fill that prescription for healthful cooking.

Be sure to cut vegetables into uniform-sized, larger pieces. Cutting into small pieces means that more surface area is exposed to heat, which can result in more nutrients lost. Peel thinly, if at all, because many nutrients are right under the peeling.

However, remember that vegetables and fruits prepared in any way provide health benefits. On average, we adults need at least 4 ½ cups of fruits and vegetables (total) per day.

Also, keep in mind food safety when cooking food in the microwave. Foodborne illness outbreaks have occurred when people haven't cooked protein foods properly in microwave ovens.

To be sure that your food cooks evenly in a microwave oven, follow these steps:

• Rotate food in the microwave as it is cooking.

• Interrupt the cooking halfway through the heating time and stir or turn food.

• Arrange food items evenly in a covered dish.

• Cover the dish with a microwave-safe lid or plastic wrap to help distribute the heat evenly inside the container. Allow enough space between the food and the top of the dish so that plastic wrap does not touch the food. Loosen or vent the lid or wrap to allow steam to escape.

• Always allow standing time at room temperature, which completes the cooking, before checking the internal temperature with a food thermometer.

For more information about microwave ovens in a fun, interactive format, see https://tinyurl.com/MicrowavingTips , which is an online publication with videos. I had fun working on the project with my colleagues at the University of Nebraska. Here's one of the easy microwavable recipes included in the publication.

Microwave Oatmeal

2 cups rolled oats (quick or old-fashioned)

4 cups low-fat milk (or water)

⅛ teaspoon salt

Mix together oats, milk (or water) and salt in a large microwave-safe bowl. Microwave on high for five to six minutes, stirring every two minutes, until oats are soft and most of the liquid has been absorbed. Spoon into bowls and serve while hot. Top with brown sugar and milk if desired.

Try these variations:

Apple Cinnamon Oatmeal: Add two unpeeled apples, chopped, 1 teaspoon vanilla and 1 teaspoon ground cinnamon to the oats and milk.

Pumpkin Spice Oatmeal: Add ½ cup pumpkin puree, ¼ cup raisins, 3 tablespoons brown sugar, 1 teaspoon vanilla flavoring, ½ teaspoon ground cinnamon and ½ teaspoon pumpkin pie spice.

Banana Walnut Oatmeal: Add one large mashed banana, 1 teaspoon vanilla and 1 teaspoon ground cinnamon to the oats, water or milk and salt. Cook according to directions. Stir in ½ cup toasted chopped walnuts and serve.

Makes five servings. Each serving of the original recipe has 206 calories, 4 grams (g) fat, 11 g protein, 32 g carbohydrate, 3 g fiber and 150 milligrams sodium.

Garden-Robinson is a food and nutrition specialist for the NDSU Extension Service.