Digestion of food is a complex but necessary process for breaking down and absorbing food in the human body. Digestive organs include the mouth, esophagus, stomach, small intestine and colon; the digestive tract is about 30 feet long, according to the Nemours Foundation. The amount of time it takes for food to digest and pass through the human body depends on the composition of food consumed.
Carbohydrates
Simple and complex carbohydrates found in foods digest fairly quickly compared to other nutrients such as protein, fat and fiber. Complex carbohydrates take longer to digest than simple carbohydrates. The Dietary Guidelines for Americans 2005 recommend consuming a diet consisting of 45 to 65 percent of daily calories from carbohydrates. Foods high in complex carbohydrates include potatoes, cereals, bread, rice, pasta legumes and starchy vegetables. Foods containing simple carbohydrates include fruits, nonstarchy vegetables, milk, honey, table sugar and sweets.
Protein
According to the National Digestive Diseases Information Clearinghouse, protein spends more time digesting in the stomach than simple and complex carbohydrates. Proteins are broken down from large protein particles into smaller amino acids. Foods high in protein include meat, eggs, dairy products and dried beans. The Dietary Guidelines for Americans 2005 recommend consuming a diet containing 10 to 35 percent of total calories from protein.
Fat
Fats are broken down into fatty acids and cholesterol inside the body, and spend a longer period of time digesting in the stomach than do carbohydrates and protein, according to the National Digestive Diseases Information Clearinghouse. Because of the slower digestion process of dietary fat, high-fat foods tend to make a person feel fuller longer than after eating low-fat foods. Dietary Guidelines for Americans 2005 recommend consuming a diet that is 20 to 35 percent of total calories from fat. High-fat foods include butter, margarine, whole milk, cheese, high-fat meats, vegetable oils and avocados.
Fiber
Little if any fiber from foods is actually digested and absorbed by the human body; therefore high-fiber foods can help with weight management. According to Medline Plus, soluble fiber helps slow the digestion process while insoluble fiber may help food digest and pass more quickly through the digestive system. Dietary Guidelines for Americans 2005 recommend consuming 14 grams of fiber per 1,000 calories. High-fiber foods include whole grains, cereals, fruits, vegetables and legumes.
Vitamins
During the digestive process, vitamins from foods are absorbed by the small intestine. Two types of vitamins, water-soluble and fat-soluble vitamins, react differently in the human body during digestion. According to the National Digestive Diseases Information Clearinghouse, fat-soluble vitamins can be stored in the body, while water soluble vitamins are not easily stored and excess amounts are excreted in urine. Water-soluble vitamins include B vitamins and vitamin C; vitamins A, D, E and K are fat-soluble vitamins.
