Sugar Terminology
In the previous blog we spoke about the affects that sugar has on your brain and your body. I just want to clarify some of the common types of sugar you will come across and the way in which each functions within your system.Carbohydrates are classified into two basic groups, complex carbohydrates and simple carbohydrates.
Complex carbohydrates are composed of many simple sugars, joined together by chemical bonds. The more chains and branches of simple sugars, the more complex a carbohydrate is. The more complex a carbohydrate is the longer it takes to be broken down by the body and the less impact it has on blood sugar levels. Simple carbohydrates are either monosaccharides (one sugar molecule) or disaccharides (two sugar molecules). The two main monosaccharides are glucose and fructose. The two main disaccharides are sucrose (composed of glucose and fructose) and lactose, which is made up of galactose and glucose.Remember I said to look out for the names ending in –OSE!
Glucose
Glucose is the main source of energy for the body. Every cell uses Glucose in order to function. When we talk about Blood sugar, we are referring to the amount of Glucose in the blood. Every carbohydrate we eat will eventually be broken down into glucose by the body in order for it to be used or stored. As the blood glucose level rises, Insulin is secreted by the pancreas so that the glucose can be absorbed by the cells to be used or stored. There is a rating for how quickly this can happen in each kind of food. It is called the Glycaemic index (GI). Glucose is the defining standard and has a rating of 100. So the glycaemic index of a food is the speed at which it is able to make your blood sugar rise.
As mentioned earlier, blood glucose stimulates insulin release from the pancreas, it also results in the release of two other hormones, leptin and ghrelin. Leptin is known as the “fullness” hormone and ghrelin the “hunger” hormone. It is thought that lower GI foods (such as whole grains, proteins and those lower in glucose) suppress ghrelin, therefore making us feel full and controlling our hunger.
Fructose
Fructose or fruit sugar is a simple sugar naturally occurring in honey, tree and vine fruits, flowers, berries, and most root vegetables. Commercially, fructose is frequently derived from sugar cane, sugar beets, and corn. High-fructose corn syrup (HFCS) is a mixture of glucose and fructose. Fructose is very sweet, roughly one and a half times sweeter than sucrose (white sugar). Because of the worldwide increase in the consumption of sweeteners, soft drinks and foods containing high fructose corn syrup (HFCS), fructose intake has quadrupled since the early 1900s.
Fructose is absorbed directly into the bloodstream during digestion and has no effect on insulin production or blood glucose levels. It was once thought this made it a good substitute for table sugar, but there is now a growing body of research to question this. Fructose is handled by the body in a different way to glucose as it is metabolised in the liver. As a result, blood glucose levels do not rise as rapidly after fructose consumption compared to other simple sugars. When you eat too much fructose the liver cannot process it fast enough and instead it starts to make fats, which are carried in the bloodstream and stored as triglycerides - the body’s main form of fat. Studies have shown that the consumption of large amounts of fructose may lead to increased appetite by decreasing the body’s ability to use insulin and allowing too much circulating ghrelin. Simply put, Fructose will make you hungry!
Sucrose
Sucrose is crystallised sugar produced by the sugarcane plant and can be found in households and foods worldwide. Sucrose is a disaccharide made up of 50% glucose and 50% fructose and is broken down rapidly into its constituent parts.Due to its glucose content, sucrose has a GI value of 65. As it is made up of glucose and fructose, the latter is metabolised in the liver and holds the same issues as those mentioned for fructose above. Due to its glucose content, sucrose does lead to an elevation in blood glucose.
Lactose
Lactose is a sugar found in milk. It is a disaccharide, and is made up of glucose and galactose. Lactose is broken down into the two parts by an enzyme called lactase. Once broken down, the simple sugars can be absorbed into the bloodstream. Whole milk has a GI value of 41 and is considered to be a low GI food. It is broken down slowly. Some people experience lactose intolerance – an inability to produce the lactase enzyme that breaks down milk. Lactose intolerance (which we will discuss soon) can lead to diarrhoea, bloating and other gastrointestinal symptoms.