A study conducted by the U.S. Dept. of Agriculture's Economic Research Service (USDA ERS) shows that Americans often eat vegetables prepared in ways that add calories and sodium and remove dietary fiber.
The ERS researchers used nationally representative dietary data from the 2003–04 National Health and Nutrition Examination Survey (NHANES). The participants reported everything they ate and the amount consumed over a 24-hr period, and the interview was repeated on a second, nonconsecutive day, providing two days of dietary intake data for each participant. USDA nutrient data were used to estimate the calorie and nutrient content of every food item consumed. At the time the study was conducted, a database to identify vegetable content of foods was not available for NHANES data newer than 2004. However, eating patterns observed in 2003–04 are likely to be similar to those today since food preferences and eating habits change slowly.
ERS researchers aggregated individual vegetable consumption from all sources—plain raw or cooked vegetables; vegetables from mixed dishes such as soups, stews, and pastas; juices; sauces; etc.—and generated overall estimates of cups of vegetables consumed. Because Americans often make quite different choices when eating out, they examined vegetable consumption patterns for food prepared at home versus those for food prepared away from home. They separated foods by where prepared, so a sandwich made at home and taken to work for a brown-bag lunch would be considered a home-prepared food, whereas a pizza taken home from a restaurant would be considered as prepared away from home. They examined the effects of the types of vegetables consumed on intake of calories, sodium, and dietary fiber.
The researchers found that on average, Americans ate 1.5 cups of vegetables daily, about 50–60% of the 2–3 cups recommended for adults and older children. More than half of vegetable intake came from potatoes and tomatoes (51%), whereas only 10% came from dark green and orange vegetables. Some vegetables were eaten in their unadorned state—raw carrot sticks or sliced tomatoes—but most were consumed in prepared forms or as part of mixed dishes.
Potatoes were typically consumed in forms that added fat. At home, potato chips were the most commonly eaten form, whereas away from home, fried potatoes predominated. Other potato dishes, such as mashed and scalloped potatoes, are often prepared with added fats and sodium. Baked potatoes were popular, but most commonly—especially when eating out—the skin was not eaten, reducing dietary fiber content.
Although popular raw, most tomato is consumed as an ingredient in popular mixed foods, such as pastas and pizzas. When the researchers examined the leading sources of tomato consumed, they found that at home, raw tomato accounted for 22% of tomato consumption, while 24% came from tomato sauces for spaghetti and similar pastas. Among foods prepared away from home, pizza provided the largest share of tomato consumed, at 32%, followed by raw tomato at 17%, and spaghetti and similar pastas with tomato sauce at 15%.