Fats, Protein, Carbohydrates, and Digestion

Certain digestive organs release digestive juices necessary for digestion. These digestive juices contain enzymes that break down nutrients in to their component parts, when they can be used. The salivary glands, stomach, pancreas, liver, and small intestine all release digestive juices. Carbohydrase is an enzyme that breaks down carbohydrates, lipase, is an enzyme that breaks down fat, and protease is an enzyme that breaks down protein.

When carbohydrate rich foods, such as breads, pastas, and potatoes, are consumed are first eaten, the salivary glands in the mouth will secrete saliva to help moisten and lubricate the food. The saliva contains an enzyme that will initiate digestion of the carbohydrate. Next, digestion continues in the upper storage area of the stomach. When the carbohydrates move to the lower area of the stomach, they are mixed with hydrochloric acid and another enzyme in the stomach juices that stop the digestion. Next, the pancreas will produce and release a carbohydrate-digesting enzyme in to the small intestine. The lining of the intestine contains enzymes on the surface that will break down sugar and starch fragments in to simple sugars, which are absorbed. Any undigested carbohydrates reach the large intestine and are broken down further by intestinal bacteria.

http://goodcarbs.org/

Fat is digested in a manner different from that of carbohydrates. First, fat-rich foods are mixed in your mouth with saliva. The tongue produces small amounts of a fat-digesting enzyme that begins the digestive process. This enzyme is very helpful in breaking down milk fat and is stable at low ph. Next, fat will rise from the stomach fluid and will float. Fat is the last to leave the stomach. The liver will secrete bile, which is stored in the gall bladder. The bile emulsifies fat and gets it ready for enzymes. The pancreas produces fat digesting enzymes and releases them in to the small intestine to split fats in to fatty acids, where they are absorbed. Some fatty materials are not absorbed and are carried out of the body with other wastes (Sizer & Whitney, 2012).

Digestion of protein also begins in the mouth. Protein-rich food is crushed during chewing and is mixed with saliva. Next, the protein-rich food is transported to the stomach, where it is mixed hydrochloric acid, where the protein strands are uncoiled. When this occurs, the stomach will release a protein digesting enzyme. This enzyme will break down the protein strands into small fragments. Next, enzymes from the small intestine and pancreas will take these smaller protein fragments and break them down in to even smaller fragments or amino acids. The enzyme on the intestinal lining will also break down protein fragments in to amino acids, which are then absorbed. The large intestine will carry any undigested protein out of the body; however, most protein is digested and absorbed (Sizer & Whitney, 2012).

I have just explained how components vital in creating energy are digested and absorbed by the human body. Fats is necessary to supply nutrients to the body. On average, most people require twenty-percent of their daily energy to come from unsaturated fat. There are three types of fatty acids: saturated fats or trans-fats, monounsaturated fats, and polyunsaturated fats. Saturated fats and trans-fats should be limited and replaced with polyunsaturated and monounsaturated fats. Fish and vegetable oils are rich in polyunsaturated fats. Olive oil and canola oil are examples of oils high in monounsaturated fat. The 2010 dietary guidelines offers suggestions for reducing trans-fats and other saturated fats from your diet and replacing them with polyunsaturated and monounsaturated fats. For example, replacing meat with seafood or buying fat-free milk.

Lastly, fiber is a critical component to one’s diet. Many carbohydrate rich foods are also rich in fiber. Whole grains, vegetables, legumes, and fruits are examples of fiber-rich foods. Fiber promotes normal blood cholesterol, normal blood pressure, modulation of blood glucose, healthy bowel function, and promotes healthy body weight.  The average intake of fiber for people in the United Stated is less than half of the daily-recommended intake. Many argue that this is a major factor in the rising obesity epidemic in America (Slavin, 2005).

Sizer, F. & Whitney, E. (2012). Nutrition: Concepts and controversies, MyPlate Update (12th ed.). Mason, OH: Cengage Learning. Package

Slavin, J. L. (2005). Dietary fiber and body weight. Nutrition, 21(3), 411-8. doi:http://dx.doi.org/10.1016/j.nut.2004.08.018