Sweeteners are a general class of additives that can be added to food to substitute the use of sugar. They are food additives that are used to stimulate the sweet taste or our system when we consume them. They are used to reduce the side effects of sugar which are blood sugar levels and diabetes. Sweeteners generally contain almost no calories. There are a lot of compounds that can be used as substitutes but not all of them are utilized for this purpose. A good example is this is the use of lead acetate which is a highly sweet substance but is also highly toxic.
Here are two main types of sweeteners, they are nutritive sweeteners and non-nutritive sweeteners. The former type of sweeteners (nutritive) are defined as the type of sweeteners that can be digested by the human body to at least some extent. This means that these type of nutritive sweeteners have some value in the metabolism. The non nutritive type of sweeteners are exactly the opposite meaning that they have none or almost no value of food energy in the metabolism.
Sugar can be classified as a nutritive sweetener but sugar is a general name given to a class of substances that are crystalline. This is confused with sucrose which is a commonly called as table sugar. By scientific meaning, sugar is a substance that is either a singular or (mono) saccharide or a di-saccharide. To explain in a few line, a monosaccharide is a singular unit of sugar or a single unit of the simplest form that sugar can be represented. A Disaccharide is simply a combination of two monosaccharide units.
The other kind of nutritive sweeteners are sugar alcohols. These type of nutritive sugars are neither sugars nor are they alcohol that can be consumed. These are just water soluble and white substances that can be used for multiple purposes. The most common of these purposes are as thickening agents and sweetening agents. Xylitol is an industry grade sweetening and thickening agent that is a sugar alcohol. Xylitol is also used in a lot of other procedures such as dental hygiene and also as a source of energy. Like other artificial sweeteners, Xylitol also has side effects as it is found to be highly toxic during some research involving dogs and certain species of birds.
Artificial sweeteners on the other hand are non nutritive and contain no value in the food nutrition scale. Most commonly used artificial sweeteners are aspartame and saccharin. These are chemically synthesized compounds that deliver the sweetness without adding any calorific value to the substance. These although are harmful if used in large quantities and can lead to adverse effects like obesity and hearth disease.