Structure & Function of Sucrose

Plants produce sucrose during photosynthesis, making it the most abundant sugar in nature. Cane sugar and sugar beets are exceptionally rich sources, so their sucrose is extracted to produce granulated sugar. This is why you may know sucrose better by the name table sugar. Sucrose in any form gives you a boost of energy, but it's only healthy when it comes from natural fruits and vegetables.

All sugars are made from three basic building blocks -- carbon, hydrogen and oxygen -- connected to form different structures. Sucrose consists of one molecule of glucose connected to one molecule of fructose. The connection between the molecules, called an acetal oxygen bridge, makes sucrose a non-reducing sugar, which means it’s less reactive than most other sugars. This doesn't affect its digestion or function in your body, but it makes a difference during cooking. Because it's non-reducing, sucrose can't participate in a chemical change called the Maillard reaction -- this allows other sugars to interact with amino acids in food, turning food brown and boosting its flavor.

Sucrose has one essential job to perform: It provides energy for your body. When you consume sucrose, digestive enzymes break the bond between fructose and glucose, and these two sugars enter your system. When glucose reaches the bloodstream, insulin transports it into cells throughout your body, where it’s converted into energy. Fructose is metabolized in the liver, where it's turned into fat. The fat may be used for energy or stored in adipose tissue, but it can also accumulate in the liver and potentially cause problems, according to the Harvard Medical School.

The glycemic index measures how much carbohydrate-containing foods boost your blood sugar. Foods are rated using a scale of zero to 100, where 100 equals the large spike caused by glucose. With a few exceptions, such as starchy vegetables, fruits and vegetables that contain sucrose have low glycemic scores because their fiber content slows down the absorption of carbohydrates. Even as a sweetener, fructose has a low glycemic score of 23, which helps balance the high glycemic score of glucose when they're combined to make sucrose. In the form of table sugar, sucrose has a score of 65, which places it in the upper portion of the moderate range.

When you eat fruits and vegetables, their natural sucrose provides a healthy source of energy because it’s part of foods rich in other important nutrients. But health problems can arise if you consume too much sucrose, whether it comes from a spoonful of table sugar stirred into tea or a sweet dessert. The calories from added sucrose -- 16 calories in 1 teaspoon, or 4 grams -- can also contribute to weight gain, which increases your risk of developing diabetes and cardiovascular disease. Women should limit their consumption of added sugar to no more than 6 teaspoons daily, while men should stay below 9 teaspoons, according to the American Heart Association.