Diets high in fruits and vegetables are widely recommended for their health-promoting properties. Fruits and vegetables have historically held a place in dietary guidance because of their concentrations of vitamins, especially vitamins C and A; minerals, especially electrolytes; and more recently phytochemicals, especially antioxidants. Additionally, fruits and vegetables are recommended as a source of dietary fiber.
Most countries have dietary recommendations that include fruits and vegetables. Table 1 summarizes the recommendations for 3 countries: Canada (1), the United Kingdom (2), and the United States (3). Although dietary recommendations have many similarities, different countries choose different strategies to separate fruits and vegetables into groups. Orange fruits and vegetables are often high in carotenoids and are placed in a separate category. Yet many dark green vegetables (i.e., spinach) are also high in carotenoids. Dividing fruit and vegetables into color categories makes sense for menu planning but does not correspond with nutrient content.
Certain fruits and vegetables are rich sources of vitamin C, but these rich sources (citrus fruits, strawberries, green peppers, white potatoes) are spread over many fruit and vegetable categories. Other fruits and vegetables, including avocado, corn, potatoes, and dried beans, are rich in starch, whereas sweet potatoes are mostly sucrose, not starch. Fruits (except bananas) and dark green vegetables contain little or no starch. Often, dietary guidance rules place fruit juices and potatoes in separate categories, because of dietary directives to eat whole fruits and minimize consumption of foods high in fat and sodium, i.e., French fries. The vegetable and fruit categories in the 2010 Dietary Guidelines for Americans (3) are listed in Table 2. These categories are important, because they drive policy for programs such as school lunch and other supplemental feeding programs.
According to the Dietary Guidelines for Americans 2010, nutrients of concern in the American diet include potassium, dietary fiber, calcium, and vitamin D. Energy density and intake are also important issues in the American diet. Fruits and vegetables are generally low in energy density and often are good sources of fiber and potassium, but the nutritional contribution of standard servings of fruits and vegetables varies widely (4). The content of phytochemicals, such as polyphenolics, also varies greatly (5) and is not listed in nutrient databases.
We have provided a nutritional comparison of the 10 most commonly consumed fruits and vegetables (Table 3). It should be noted that fruits and vegetables are often not consumed in the raw form but may be cooked, fried, or combined with other ingredients prior to consumption. Thus, whereas a boiled potato is a nutrient-dense food, a fried potato may contribute a substantial amount of fat and sodium to the diet. Fiber concentrations range from 0.6 to 5.1 g/serving and potassium concentrations range from 76 to 468 mg/serving (Table 3). Bananas and potatoes, although technically belonging to different families, have strikingly similar compositions for energy, fiber, and potassium per standard serving. A standard serving of iceberg lettuce contains 8 kcal, whereas a potato contains 144 kcal and a banana 105 kcal. Of course, iceberg lettuce is seldom eaten alone.
Most estimates of fruit and vegetable consumption are limited by disagreement on what constitutes a serving of a fruit or vegetable. Mean fruit and vegetable intakes (servings/d) are 5.16 servings (Canada), 3.5 portions (men); 3.8 portions (women) (UK) and 4.7 servings (US) (Table 1). Marriott et al. (6) examined intake of carbohydrates, including dietary fiber, in the NHANES data set. Dietary fiber intake was particularly low in their analysis. With the exception of older women (≥51 y), only 0–5% of individuals in all other life stage groups had fiber intakes meeting or exceeding the Adequate Intake (AI)4. Common serving sizes of fruits and vegetables contain 1–5 g of fiber. Most of the fiber in vegetables and fruits is insoluble fiber, except for citrus fruits.
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