Carbohydrates, along with fats and proteins, make up one of the main categories of food. Providing the body with energy, especially the brain, is the primary function of carbohydrates, notes Medline Plus. Carbohydrates are divided into two groups: simple carbohydrates, which have one or two sugars and are absorbed more quickly, and complex carbohydrates, which have three or more sugars and are absorbed more slowly. It is recommended that people get between 40 and 60 percent of their total calories from carbohydrates, although complex carbohydrates are preferred. However, not all simple carbohydrates are found in highly processed foods with abundant refined simple sugars, which provide very little nutrition. Some occur naturally in various food sources.
Fructose is a simple carbohydrate composed of one sugar that is found naturally in fruits, notes Medline Plus. While fructose from fruit sources is beneficial because it's accompanied by vitamins and other nutrients, highly processed fructose, like that found in soft drinks and other highly refined foods, usually in the form of high fructose corn syrup, has been shown to have negative health effects. The Globe and Mail reported on a study recently which showed that, while all sugars tend to feed cancer cells, fructose was a powerful activator of cancer cell division.
Galactose and Lactose
Galactose is a simple carbohydrate composed of one surgar molecule that occurs naturally peas and in milk products, although it is found more commonly in lactose, which is a double sugar made up of glucose and galactose, according to Vertual Chem Book. Of every 18,000 babies born, one will have a genetic defect and be unable to digest galactose. However, this condition will right itself because maturation results in the development of an enzyme to metabolize galactose.
Maltose is found in some vegetables and beer, notes Medline Plus. Maltose is a double sugar, formed by two glucose molecules. Maltose, also known as malt sugar, occurs least commonly in nature. In the process of making beer, barley grains must be "malted," which brings the grain to the point of its highest possible starch content. Then the sugar is fermented by the yeasts to create beer.
Sucrose is a double sugar made up of a fructose and a glucose molecule. Sucrose is commonly used as table sugar. It is also found in maple syrup, brown sugar, powdered sugar and beet sugar or cane sugar. These sugars, with the exception perhaps of maple syrup, are considered to be refined sugars which provide calories, but are lacking in other nutrients like vitamins, fiber and minerals, notes Medline Plus. Calories from refined sugars are considered to be "empty calories" for this reason and can result in weight gain. Medline Plus notes, that it is healthiest to choose carbohydrates with vitamins and other nutrients from natural sources like fruit, instead of table sugar.