THE HEALTH BENEFITS OF FRUITS AND VEGETABLES

THE HEALTH BENEFITS OF FRUITS AND VEGETABLES

Health researchers have recommended that  you make one-half of your plate fruits and vegetables.. Fruits and vegetables include a diverse group of plant foods that vary greatly in content of energy and nutrients. Additionally, fruits and vegetables supply dietary fiber, and fiber intake is linked to lower incidence of cardiovascular disease and obesity. Fruits and vegetables also supply vitamins and minerals to the diet and are sources of phytochemicals that function as antioxidants, phytoestrogens, and antiinflammatory agents and through other protective mechanisms. In this review, we describe the existing dietary guidance on intake of fruits and vegetables. We also review attempts to characterize fruits and vegetables into groups based on similar chemical structures and functions. Differences among fruits and vegetables in nutrient composition are detailed. We summarize the epidemiological and clinical studies on the health benefits of fruits and vegetables. Finally, we discuss the role of fiber in fruits and vegetables in disease prevention.

Introduction

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.

Table 1

National guide analyses: Canada, United Kingdom, United States

  Canada  United Kingdom  United States 
Name  Canada’s Food Guide  Eatwell Plate  My Plate 
Agency Health Canada Food Standards Agency/National Health Service USDA
Number of food categories 4 5 6
Key messages 1. Eat at least one dark green and one orange vegetable each day.
2. Enjoy vegetables and fruit prepared with little or no added fat, sugar, or salt.
3. Have vegetables and fruit more often than juice. Try to eat plenty of fruits and vegetables Increase vegetable and fruit intake. Eat a variety of vegetables, especially dark-green, red, and orange vegetables and beans and peas.
Units Servings, cups 1 cup = 250 mL Portions (1 portion = 80 g) Servings, cups 1 cup raw leafy vegetables = 84 g
Vegetable   3 cups/d, 2400 kcal
Fruit   2 cups/d, 2400 kcal
Vegetable and fruit 7–8 servings (adult) 4–6 (children) 5 portions/d (400 g/d)
Vegetable One serving is: 1) 1 cup (250 mL) of raw green leafyvegetables, such as salad, spinach, collards; 2) 1/2 cup (125 mL) of other vegetables steamed, cooked, or raw, e.g., broccoli, snow peas, carrots; 3) 1/2 cup 100% vegetable juice A portion is 80 g of these: 1) 3 heaped tablespoons of vegetables (raw, cooked, frozen, tinned); 2) 3 heaped tablespoonsof beans and pulses (beans and pulses count a maximum of 1 portion/d); and 3) a dessert bowl of salad 1 cup green salad; 1 baked potato; 1/2 cup cooked broccoli; 1/2 cup serving of other vegetable; 1/2 cup tomato juice
Fruit One serving is: 1) 1 piece of fruit (e.g., apple, pear, 2) 1/2 cup fruit, e.g., melons, cantaloupe; 3) 1/2 cup fruit juice A portion is 80 g or any of these: 1) 1 apple, banana, pear, orange, or other similar-size fruit; 2) 3 heaped tablespoons of fruit salad (fresh or tinned in fruit juice) or stewed fruit; 3) 1 handful of grapes, cherries, or berries; 4) a glass (150 mL) of fruit juice (counts as a maximum of 1 portion/d) 1/2 cup fresh fruit; 1 medium size fruit; 1/2 cup fruit juice
Juice 100%, 1/2 cup 1 glass (150 mL) of fruit juice counts as 1 portion, but juice can only count a maximum of 1 portion/d 100% fruit juice. 1 cup. No limits
Categories 1. Dark green
2. Orange 1) Dark green; 2) red/orange; 3) beans/peas; 4) starchy; 5) other vegetables
Potatoes included? Yes No. Potatoes not included (considered starchy food) Yes
Legumes included? Yes Beans and pulses count only 1 portion/d, no matter how many one eats Yes (protein category as well), but should be counted in only one category
Intake estimates 5.16 servings (Stat Canada, 2004) Men: 3.5 portions; women: 3.8 portions 4.7 servings (NHANES 1999–2000)

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 2018 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.

Table 2

USDA Food Patterns: food groups and subgroups

Food group  Subgroup and examples 
Vegetables Dark green vegetables: all fresh, frozen, and canned dark green leafy vegetables and broccoli, cooked or raw (broccoli, spinach, romaine, collard, turnip, and mustard greens)
  Red and orange vegetables: all fresh, frozen, and canned red and orange vegetables, cooked or raw (tomatoes, red peppers, carrots, sweet potatoes, winter squash, pumpkin)
  Beans and peas: all cooked and canned beans and peas (kidney beans, lentils, chickpeas, and pinto beans). Does not include green beans or green peas.
  Starchy vegetables: all fresh, frozen, and canned starchy vegetables (white potatoes, corn, green peas)
  Other vegetables: all fresh, frozen, and canned other vegetables (iceberg lettuce, green beans, onions)
Fruit All fresh, frozen, canned, and dried fruits and fruit juices (oranges and orange juice, apples and apple juice, bananas, grapes, melons, berries, and raisins)

…… to be continued

1 Comment

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