You’ve heard of glucose, fructose, lactose and sucrose. Have you wondered what these are? All four are forms of sugar found in food. Broadly sugars can be differentiated as:
Naturally-occurring sugars – like unrefined fructose in fruit, and lactose in milk.
Added sugars – including sucrose and HRCS.
Artificial sugars – such as saccharine and aspartame.
Let’s understand what each of these terms means.
Glucose is our primary source of energy. It is derived from the carbs we eat, which are broken down into units of glucose. When we speak of ‘blood sugar’ we are referring to glucose in the blood. When this is released into the bloodstream, the pancreas creates insulin to absorb and use the glucose.
The form of sugar that forms the basis for the Glycemic Index, glucose is the standard with a value of 100. The value of a food on the GI indicates the speed at which it can be broken down into glucose and absorbed into the bloodstream.
Foods that are high on the GI get converted into glucose faster and absorbed sooner into your system, leaving you hungry more quickly than foods lower on the index. Low GI foods leave you satiated and feeling fuller for a longer time.
Fructose is 1.5 times sweeter than white sugar. It is the naturally-occurring form of sugar found in fruit, honey, etc.. It gets absorbed into the bloodstream directly, and has no bearing on glucose levels or insulin production.
At 19 on the GI, fructose is lower than glucose. It was once believed to be a substitute for table sugar, but this piece of wisdom is now being questioned. Fructose is processed by the liver; when too much is consumed, the organ is unable to process it fast enough and converts it into fats which are then stored as triglycerides. Not a good thing!
Watch out for sweeteners like High Fructose Corn Syrup (HFCS or glucose-fructose) which have a higher GI because of the glucose content. You’ll find these in soft drinks, concentrated juices and shakes, and most processed foods including boxed mac-and-cheese, tinned fruit, cocktail peanuts, and salad dressings.
While HFCS is super-inexpensive when compared to table sugar, it leads to increased appetite and is now considered a cause of cardiovascular disease and type-2 diabetes.
Most diabetics can tolerate moderate quantities of fructose without messing up their blood sugar control. But they must keep in mind that excessive HFCS and other sweeteners contribute to increased blood sugar, body fats, and weight gain.
Sucrose, or table sugar, can be found in almost all homes across the world. It is the sugar we stir into tea and coffee, and use to sweeten cakes and biscuits and a ton of other stuff we eat. It is sweet, but not as sweet as refined fructose and artificial sweeteners.
Made up of equal parts of glucose and fructose (1:1), sucrose is extracted from the sugarcane plant and ultra-refined to form crystallised white sugar. The glucose in sucrose causes blood sugar to increase, while the fructose is processed by the liver, with excess being stored as triglycerides.
With a value of 65, sucrose is higher on the GI than honey and unrefined fructose. Because of its high GI value, it is easily broken down and absorbed into the system. When you eat food that is high in sucrose, your blood sugar will increase almost instantaneously and give you what’s called a “sugar rush”. This “high” is only temporary and fades as soon as the sucrose is absorbed by your body.
Natural sucrose is found in dates, beets, peas, nuts, dried fruit, and some fresh fruit like peaches, mangoes, and grapes. Foods with added sucrose include baked goods and processed foods; these contain a table or baking sugar, and even maple syrup, processed honey, and chocolate.
Lactose is a sugar found in milk. It is composed of glucose and galactose and is broken down by lactase, which is an intestinal enzyme. Once broken down, the simple sugars in it are absorbed into the bloodstream.
Whole milk has a value of 41. Milk is considered a low GI food and is metabolised rather slowly, helping in the absorption of the minerals – calcium, magnesium, and zinc – in it. Some infants and even adults are unable to produce lactase, which breaks down milk. This causes lactose intolerance, leading to diarrhoea and other gastrointestinal disorders. Such people have to avoid milk and milk products.
Now that we know about the kinds of sugar and how they work inside our bodies, what are the conclusions? Watch this space for this and more about sugar. We’ll be back with you very soon!
Until then, tra-la!