The carbohydrate food group is one of three sources of nutrients and energy necessary for human survival. If you have seen the food pyramid, you will notice that there is no specific label for carbohydrates.
Carbohydrates are composed of a diverse group of foods – including grains, fruits, milk, and vegetables.
Factoid: Carbohydrate food molecules are made up of carbon, hydrogen, and oxygen. The molecules are produced through photosynthesis, in which plants combine carbon dioxide, water, and light energy into a compound with a 1:2:1 carbon-hydrogen-oxygen ratio.
To use the energy, our digestive system needs to break down, or metabolize, the carbohydrate. Each gram of carbohydrate has four calories (a unit of food energy). While this is fewer than the nine calories from a gram of fat, many people believe that carbohydrates are energy-rich and thus contribute to weight gain.
However, low-carbohydrate diets can be dangerous. Without a proper intake of carbs, the body resorts to breaking down fat for energy, in the process releasing substances that will disrupt normal blood acidity.
Instead, about 60 percent of total caloric intake should come from carbohydrates. Many foods contain carbohydrates:
- One slice of bread: 15 grams
- 1/4 bagel: 15 grams
- One cup raw leafy vegetables: 5 grams
- One medium apple or orange: 15 grams
- One cup milk: 15 grams
Simple carbohydrates are composed of single-unit sugars called monosaccharides and disaccharides. Glucose and fructose are examples of common monosaccharides. Simple carbohydrates are easily digested and converted to sugar rapidly in the bloodstream.
This can cause trouble for people with diabetes. If you have diabetes, you should be careful since carbohydrates – especially simple ones – can raise blood sugar very quickly. Examples of simple carbohydrates include fruit, honey, juice, and candy.
Complex carbohydrates (or polysaccharides) are built from single-unit sugars joined in long chains. Two types of complex carbohydrates are particularly important for nutrition:
- Starch: Starch is a polysaccharide that plants use to store energy. It is the main constituent of complex carbohydrates in the human diet. Examples of starchy foods include potatoes, rice, and pasta.
- Dietary Fiber: Dietary fiber is found in plants as cellulose, pectin, and lignin. Although its rigid bonds are resistant to digestive enzymes and thus pass through your digestive system intact, fiber is extremely important in maintaining good health.
Benefits of Fiber
Some benefits of fiber include:
- Regulation of blood sugar: Fiber slows down the digestion of other foods while it is eaten, and helps prevent large changes in blood sugar.
- Lowering of blood cholesterol: Fiber binds fatty acids and cholesterol into large clusters that your body can get rid of more easily.
- Promotion of intestinal health: Fiber aids digestion and helps prevent constipation and hemorrhoids by regulating bowel movements.
The more refined the food, the less fiber it contains. (See Nutritional Effects of Refining and Enrichment on Wheat and Rice to see the effects of refinement.)
Try to eat at least 20 grams of fiber daily. Foods high in fiber include:
- Cooked split peas, one cup: 16 grams
- Boiled red kidney beans, one cup: 13 grams
- Whole wheat spaghetti, one cup: 6 grams
- Boiled broccoli, one cup: 5 grams
- Medium pear, with skin: 5 grams
- Medium apple, with skin: 4 grams
- Slice of whole wheat bread: 2 grams
Written By: Christina Ma
Reviewed By: Nancy Brown, Ph.D.
Last Reviewed: October 2013
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ChooseMyPlate.gov: MyPlate illustrates the five food groups that are the building blocks for a healthy diet using a familiar image – a place setting for a meal.