Popcorn is one of the most popular snack foods in the world. However, the taste treat provides little in the way of nutrition, apart from the calories it offers from carbohydrates. When butter is added, the increased levels of calories from fat, saturated fat and salt can reduce the nutritional value of this food even further.
A typical 2-cup serving of popcorn, popped in oil, then served with butter, provides around 170 calories, according to the U.S. Department of Agriculture. This single serving delivers over 8 percent of the calories required by an adult on a daily diet of 2,000 calories.
Over half of a serving of buttered popcorn consists of fat. While some fats are actually healthy within the diet, buttered popcorn can contain over 3 g of saturated fat. High levels of saturated fat in the diet can lead to an increased risk of heart disease. For the average person, 3 g is around 25 percent of the recommended daily intake, or RDI, of saturated fat.
Buttered popcorn contains relatively low levels of vitamins. The USDA notes that the highest of these is vitamin E at 0.7 mg or around 4.5 percent of the recommended dietary intake. While a 2-cup serving contains other vitamins, including vitamins A, B-6, B-12, and K, niacin, riboflavin and folate are available only in trace amounts.
To add more flavor, buttered popcorn is often heavily salted. Salt is a dietary source of sodium, which can increase blood pressure. This, in turn, can adversely affect other chronic medical disorders, including cirrhosis, kidney disease and cardiovascular disease and can increase the risk of stroke, according to MayoClinic.com. The USDA indicates that a 2-cup serving of buttered popcorn contains 285 mg of sodium, on average. This amount equals almost 20 percent of the RDI for this element.