It’s no secret that the standard American diet, which emphasizes animal protein, processed foods and sugary beverages over vegetables, fruits and whole grains, is significantly lacking in dietary fiber. According to the 2010 Dietary Guidelines for Americans, most adults in the United States consume an average of 15 grams of fiber a day -- an amount of fiber equivalent to the daily recommended intake for most 1-year-olds.
Calories and Fiber
The amount of fiber you should get is directly related to the number of calories in your diet. According to the U.S. Department of Agriculture, evidence indicates that the more calories you consume, the more fiber you need in your diet to receive its health benefits, regardless of your age, gender or body weight. The adequate intake for fiber is 14 grams per 1,000 calories. Accordingly, the typical 2,000-calorie diet requires a daily intake of 28 grams of fiber. To figure out your individual needs, multiply the number of calories you average each day by a conversion factor of 0.001, then multiply that amount by 14. For example, a 2,300-calorie diet requires about 32 grams of fiber per day: (2,300) x (0.001) x (14) = 32.2.
Because most people don’t keep track of their calories, fiber recommendations are also given in the form of general guidelines. While these guidelines appear to be based on age and gender, they’re actually issued from the suggestion of getting 14 grams for every 1,000 calories, assuming that most people consume the amount of calories recommended for their age and gender. Through the age of 50, general dietary guidelines recommend that most men and women get 38 grams and 25 grams per day, respectively, while men and women over the age of 50 require just 30 grams and 21 grams of fiber a day, respectively.
Soluble Vs. Insoluble
The term dietary fiber refers to an array of substances that provide distinct health benefits. These compounds are generally classified as either soluble or insoluble. Soluble fiber dissolves in water to form a gel-like substance, which binds to fatty acids to promote their elimination. This type of fiber helps maintain normal cholesterol and blood-glucose levels. Insoluble fiber binds with water to help generate larger, softer stools and encourage the movement of material through the digestive tract. All vegetables, fruits, whole grains, nuts and seeds contain both types of fiber, but some foods are higher in one kind. Dietary guidelines don’t specify how much of each type of fiber you should consume; rather, they suggest eating a variety of fiber-containing foods to ensure that you get adequate amounts of both.
To qualify as high in fiber or an excellent source of fiber by U.S. Food and Drug Administration standards, a food must supply at least 5 grams of fiber per serving. Foods that provide 2.5 grams to 4.9 grams of fiber per serving are considered good sources of fiber. With nearly 8 grams of fiber per 1/2-cup serving, lentils are an excellent source of fiber. Almonds, which supply 3.5 grams of fiber per 1-ounce serving, are a good source of fiber. Although cantaloupe does provide some fiber, it doesn’t qualify as a good source -- you’d have to eat an entire medium-sized cantaloupe to get just 5 grams of fiber.
- USDA Center for Nutrition Policy and Promotion: Dietary Guidelines for Americans, 2010: Foods and Nutrients to Increase
- USDA National Agricultural Library: Dietary, Functional, and Total Fiber
- Colorado State University Extension: Dietary Fiber
- USDA Nutrient Data Laboratory: Lentils, Mature Seeds, Cooked, Boiled, Without Salt
- USDA Nutrient Data Laboratory: Nuts, Almonds
- USDA Nutrient Data Laboratory: Melons, Cantaloupe, Raw
- American Dietetic Association Complete Food and Nutrition Guide; Roberta Larson Duyff, M.S., R.D.
- Wellness Foods A to Z; Sheldon Margen, M.D., et al.
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