I thought is was because dextrose didn't need to be converted in the liver and cane sugar did.
Ah, I find this over at Yahoo! answers and jives with what I've read before. Pretty much, is says that
monosaccharides (like glucose) are the most simple for of carbohydrates and don't need to be converted in the liver, unlike
disaccharides which do.
Carbohydrates: Simple vs. Complex
What Are Carbohydrates?
Carbohydrates are combinations of carbon (C), hydrogen (H) and oxygen (O). The basic formula: CnH2nOn. All carbohydrates are made up of one or more molecules of simple sugars. They are classified by structure:
Monosaccharides or one-molecule sugars. Those commonly found in food are:
glucose (dextrose or blood sugar)
fructose (levulose or fruit sugar)
galactose (occurs mainly in milk)
Disaccharides are two monosaccharides linked together. Those common to food always contain at least one glucose molecule.
sucrose (table sugar) = glucose + fructose
lactose (milk sugar) = glucose + galactose
maltose (malt sugar) = glucose + glucose
Polysaccharides (complex carbohydrates) are made up of simple sugars (monosaccharides) or their derivatives linked together in different ways. Those found in food include:
starch - made up of several hundred glucose units joined together.
dietary fiber - consists of glucose, galactose or other monosaccharides linked together in such manners that the long chains are indigestible.
Energy From Carbohydrates
To utilize carbohydrates for energy, your body converts them to glucose. Carbohydrates--from sugars, fruits, vegetables or grains--follow a similar route in the process of digestion. Monosaccharides are absorbed and carried unchanged to the liver before distribution throughout the body. Disaccharides and the more complex starches are broken into their simple sugar constituent parts, then routed to the liver.
Sucrose, for example is broken down in the intestine to its components, glucose and fructose. These two sugars are absorbed into the bloodstream and carried directly to the liver. Some fructose is converted into glucose in the liver before it is returned to the blood for use as energy.
If the glucose is not needed right away to meet energy needs, it is converted preferentially to glycogen, the starch-like compound that is the energy reserve of human metabolism. Glycogen can be converted back to glucose when the body needs energy. Once the body's glycogen reserves are filled, any remaining glucose and fructose become involved in the metabolism of dietary fats and their physiological products.
All carbohydrate foods, such as potatoes, broccoli, apples, grapes, sugar, honey, have the same ultimate destination: they become glucose, fuel for the body.
Carbohydrates: Simple vs. Complex
In recent years, nutrition scientists have reexamined traditional views about the physiological differences between "simple" and "complex" carbohydrates. The old view was that any simple carbohydrate raised blood sugar levels very quickly because it was metabolized rapidly, while any complex carbohydrate caused a slower and more moderate rise in blood sugar.
However, research on the "glycemic index of foods" shows no defined nutritional difference between simple and complex carbohydrates. Some simple sugars cause a slow, moderate rise in blood sugar levels; some complex carbohydrates cause a rapid rise. Table sugar has a moderate effect on blood sugar--about the same as potatoes and less than bread or rice. This new knowledge has led to a better understanding of carbohydrate's role in nutrition and to increased flexibility in meal planning for people with diabetes. Carbohydrates provide the most easily accessible energy source for your body. The other main sources of energy are protein and fats. However, carbohydrates are efficiently converted into glucose which will be used for energy. Glucose is used directly by your muscles and brain. Excess glucose is stored as glycogen in your muscles. Where a supply of glucose is not available, your muscles will burn fat as a source of energy.
By being converted into glucose, levels of carbohydrates will affect your blood sugar levels. Your blood sugar levels are important because your brain uses glucose from your blood. This explains why people often get depressed and down beat whilst on diets. Your blood sugar levels are not something that should be neglected!
Carbohydrates come in two forms: Simple carbohydrates and complex carbohydrates. Simple carbohydrates contain naturally occurring sugars, such as those found in fruit (fructose) for example. The sugars that make up simple carbohydrates also include table sugar (sucrose) and a variety of syrups.
Because simple carbohydrates are already simple sugars they can rapidly be converted into glucose and enter the bloodstream very soon after consumption. This where the term "sugar fix" comes from. After drinking a sugary cup of tea, for example, you may notice a sudden release of energy and an accompanying lift in your mood. However, have too much and your body will produce insulin to counteract the effect and, depending on how much sugar you've ingested, this will likely result in a rapid drop in blood sugar level and leave you feeling more tired than before!
So what are complex carbohydrates then? Complex carbohydrates are present in most grain products, vegetables and potatoes. Unlike simple carbohydrates, complex carbs are digested at a much slower rate. As a result of this, the conversion to glucose also happens at a slower rate and your blood sugar levels will not fluctuate as rapidly as they do when digesting simple carbohydrates.
Many people will try and avoid all types of carbohydrates where possible, particularly when on weight loss diets. This is not a good idea. Carbohydrates in general are not normally a problem. It's the quality of carbohydrates that should be taken into account. Highly processed foods should be avoided. This is because they normally contain a higher proportion of simple carbohydrates. For example, whole grain bread (complex carbs) should be eaten instead of white bread which uses refined white flour (simple carbs).
Complex carbohydrates are often also lower in fat and provide higher amounts of other essential nutrients like dietary fiber. It is for the above reasons that a diet of complex carbohydrates is preferable.
