The Breakdown of Sucrose

Sucrose is a sweet carbohydrate probably best known as refined white table sugar. Sucrose is also found in many vegetables and fruits, although sugar cane and sugar beets are mainly used as sources for its commercial production. Sucrose is readily broken down or metabolized into glucose, which is the simplest sugar used by the body to produce energy and do work.

Sucrose is a disaccharide made up of two simpler sugars -- glucose and fructose. Sucrose is relatively sweet tasting, which is why it’s commonly used in baked goods, candies and as a sweetener for coffee and teas, but many other compounds are sweeter. Fructose or fruit sugar, for example, is about 70 percent sweeter tasting than sucrose. Some herbs such as stevia are up to 300 times sweeter than sucrose, whereas most artificial sweeteners such as aspartame are about 200 times sweeter. The glycemic index of sucrose, which is a measure of how quickly glucose is broken down, is absorbed into the bloodstream and triggers insulin release, is moderately high at 80 -- comparable to processed honey. Any substance rated higher than 55 can cause insulin spikes and unhealthy fluctuations in blood sugar levels.

Sucrose passes through your mouth and stomach virtually undigested. Once it enters the initial part of your small intestine, an enzyme called sucrase is secreted from the mucosal membrane. Sucrase breaks down sucrose by cleaving it in half, which produces one molecule of glucose and one molecule of fructose. The glucose is immediately absorbed into the bloodstream and transported around the body. In contrast, fructose is also absorbed in the small intestine, but it’s shuttled to the liver where it spends more time either being reduced into glucose, stored as glycogen or converted into lipids. In addition to sucrase, another enzyme called isomaltase glycoside hydrolase can also help facilitate the breakdown of sucrose. Overall, sucrose is readily assimilated and produces a quick boost of energy -- about 3.94 kilocalories of energy per gram.

Aside from baked goods, desserts, candy and beverages that contain lots of refined sucrose, some foods are naturally rich sources. Good examples include sugar cane, sugar beets, dates, carrots, apples and sweet grapes. However, keep in mind that most of the sweetness of fruit comes from the fructose content and sucrose plays only a minor role. There is no specific recommended daily intake of sucrose, but most nutritionists note that a healthy diet should include between 200 and 300 grams of carbohydrates per day.

Overconsumption of sucrose is linked to a variety of health problems. For example, the rapid breakdown of sucrose triggers large fluctuations in blood glucose levels and insulin secretion, which can be dangerous for diabetics. In fact, regular insulin spikes may be a contributing cause of type 2 diabetes, which is characterized by insulin resistance of tissues. Processed sucrose is also acidic, which promotes tooth decay and gum infections, and it may reduce immune response for at least a few hours following ingestion. High consumption of any refined sugar is also linked to increased risk of obesity and heart disease.