It’s probably safe to assume that the average American enjoys popcorn -- the whole-grain snack is consumed at a per-capita rate of about 200 cups a year, according to the U.S. popcorn industry. At its best, popcorn is low in calories and fat, a good source of dietary fiber and virtually sodium-free. Microwave popcorn -- like many processed foods -- typically sacrifices nutritional value for flavor and convenience.
A Whole-Grain Snack
The most natural form of popcorn is the air-popped variety in that every calorie, nutrient and phytochemical comes straight from the kernel. A 3-cup serving of plain, air-popped popcorn supplies just over 90 calories, 3 grams of protein, 1 gram of fat and close to 19 grams of carbohydrates, according to the U.S. Department of Agriculture. Nearly 20 percent of these carbohydrates -- or about 3.6 grams -- come from dietary fiber. More than 70 percent of the fat in air-popped popcorn is unsaturated, the kind associated with cardiovascular health.
As with all food products, the nutritional value of microwave popcorn depends on how it’s made. Regular butter-flavor popcorn made with partially hydrogenated oil provides about 132 calories, 1.8 grams of protein, 8 grams of fat -- including 2.3 grams of trans fat -- and 13 grams of carbohydrates per 3-cup serving. It’s also about 30 percent lower in fiber and has 90 times the sodium of the air-popped variety. Although regular microwave popcorn made with palm oil is slightly lower in calories and fat, it still contains trace amounts of trans fat. Low-fat varieties aren’t necessarily healthier -- according to the USDA, a product labeled 94 percent fat-free can still contain more than twice as much trans fat as regular microwave popcorn made with palm oil.
Primary Health Risk
While microwave popcorn is typically higher in calories and sodium and lower in fiber than the air-popped variety, the main reason it’s less healthy is that it often contains trans fats. The American Heart Association recommends that no more than 1 percent of your daily calories come from trans fats because consuming too many of these mostly manufactured fats promotes unhealthy cholesterol levels and increases your risk of developing heart disease and Type 2 diabetes. You’ll get about 21 calories of trans fat from a 3-cup serving of regular butter-flavor popcorn made with partially hydrogenated oil, which is the maximum amount you should consume in one day if you eat a 2,100-calorie diet.
Potential Health Risks
Microwave popcorn can also be a source of potentially harmful chemicals, including perfluorinated compounds, or PFCs, and diacetyl. PFCs make their way into microwave popcorn through the bag, which is typically coated with them. These persistent chemicals have been linked to lower fertility rates and changes in thyroid function, according to Canada's National Collaborating Centre for Environmental Health. A 2012 study published in the journal “Chemical Research in Toxicology” reports that diacetyl, a chemical widely used to give microwave popcorn its buttery taste and aroma, appears to magnify the damaging effects of an abnormal protein linked to Alzheimer’s disease.
Keeping It Wholesome
You can avoid the pitfalls of microwave popcorn and still use your microwave to make popcorn -- all you need is a lunch-sized paper bag and about 1/4 cup of popcorn kernels. Place the kernels in the bag, fold the top of the bag over twice to seal it, and microwave it on high for two minutes, or until the popping slows down. Toss it with a bit of olive oil, sea salt and freshly ground pepper for flavor.