In learning about healthy eating, you might have been told that anything with the suffix "-ose" indicates that a substance is a sugar. It's easy to get confused about why one sugar -- glucose -- is important for health, while table sugar -- sucrose -- should be avoided. Structurally, the two are very closely related, but their effects on your body are very different.
Glucose
Glucose, a molecule that is made up of carbon, hydrogen and oxygen, is the most basic form of sugar. It is part of a group of sugars called monosaccharides, which means "single sugar." It is the type of sugar that provides your body's most abundant source of fuel. When you eat any carbohydrate, including bread, pasta or starchy vegetables, the bulk of the food matter gets broken down into glucose, which is absorbed by the small intestine to power your body.
Sucrose
When simple sugars like glucose occur in a ring-shaped molecule, they can link together to form disaccharides, a group that includes sucrose. Sucrose, commonly known as table sugar, is extracted from sugar cane or sugar beets. It's frequently added to a multitude of foods, but gets broken down into glucose in your digestive system. Because sucrose is essentially two glucose-sized molecules hooked together, it's too large for your body to siphon from your digestive tract and burn as fuel. So your body expends a tiny bit of energy to break it apart, getting a large return on its energy investment.
Interactions
When you consume sucrose, the level of glucose in your blood spikes rapidly because sucrose is so quickly and easily broken down into glucose. The sheer pace of the process ensures that the fuel source won't hold out. Therefore, you experience a "crash" just as suddenly and quickly as you experienced the rush. When the sucrose is all used up, your blood glucose level drops, leaving you tired and sluggish, and may even cause a headache.
Eating Sugar
The myth that eating too much sucrose will cause diabetes is not true. Still, people with diabetes must make an effort to avoid eating excessive sucrose because the spike and subsequent drop in their blood glucose levels can be dangerous. Limit your sugar intake even if you're not diabetic because your body can get the glucose it needs from whole grains, fruits and vegetables, the only thing sucrose adds to your diet is calories. The American Heart Association recommends that men consume no more than 9 tsp. of sugar per day, and women should have no more than 6 tsp. per day.
