Sugars are the simplest form of carbohydrates and are the building blocks of other complex carbohydrates. They are mostly monosaccharides or disaccharides, meaning they contain either one or two sugar molecules.

Sugar is absorbed in the small intestine where it passes into the bloodstream. The level of sweetness and ability to raise blood sugar levels varies depending on the type of sugar molecule. You may find one or more of these in mostly pre-packaged processed foods, drinks, gums and candies, especially diet products and foods marketed to diabetics.

Here's a list of common sugar terms:

Fructose: Fructose, also known as fruit sugar, is one of three monosaccharides (glucose and galactose are the other two) and is commonly found in foods. It is a nutritive sweetener, meaning it contains calories. “Along with sucrose (table sugar), it is used to make up high fructose corn syrup, which is added to many commercial foods for taste and other reasons,” says Rachel Begun, MS, RD, spokesperson for the Academy of Nutrition and Dietetics. Natural food sources of fructose include fruits and vegetables, honey, molasses, maple syrup and agave nectar. Much attention has been paid lately to fructose, and its increased presence in the food supply has coincided with an increase in obesity. 

High fructose corn syrup: (HFCS) is a man-made sweetener found in a wide range of processed foods, from condiments and cereals to crackers and sauces. It also sweetens most regular (non-diet) soda. HFCS used in foods is 50 to 55 percent fructose. Chemically, it’s identical to table sugar (sucrose), which is also 50 percent fructose. Produced by adding enzymes to corn syrup, it’s a cheaper alternative to sugar that also functions as a preservative. There is some controversy around high fructose corn syrup, with concerns about its role in increasing obesity, especially among children.

Glucose: This is sugar in its simplest form. One of the three monosaccharides, it is a building block of dietary carbohydrates, such as corn, rice and wheat, which are then broken down by the body to make glucose, the primary energy source used by the body. Everything has to be converted to glucose before it can be used by the body for fuel. Glucose can also be made commercially from the breakdown of these starches, and is used as a sweetener in the food supply. Glucose raises your insulin faster than other sugars. Refined glucose is best avoided, and it’s not typically found in food products.

Dextrose: Dextrose is another form of glucose. It can be produced synthetically from starches, such as corn, wheat and rice. In the U.S., it is mostly made from cornstarch. “It is used as a sweetener and color-enhancer in foods, and is commonly added to cereals, baked goods and candy,” says Begun. There is no benefit to having dextrose, except when dealing with diabetes. Then, a person may be given dextrose or glucose to get blood sugar up quickly.

Maltrose: Also called malt sugar, maltose is a type of sugar made from two glucose molecules. High maltose corn syrup is another common name for it, the result of processing corn in a different way. Maltose is an important component in the process of creating fermented barley that can be used to brew beer.

Lactose: Lactose is a disaccharide made from glucose and galactose. It is the natural sugar that gives milk its sweet flavor. Many people are lactose-intolerant, experiencing gas, diarrhea and stomach upset when they consume dairy. This happens because they don’t have the enzyme to properly digest it. Lactose-intolerance is especially common in African and Asian populations. Many people avoid or reduce their dairy intake as a result.

Galactose: One of the two simple sugars, along with glucose, that make up the protein lactose, which is found in milk and dairy products. Galactose can be toxic in high levels. Found also in sugar beets, gums and seaweed, galactose is less sweet than sugar.

Invert sugar: Also known as inverted sugar syrup, this is similar to honey, maple syrup and high fructose corn syrup in that it is sucrose (table sugar) that has been separated into glucose and fructose. It has a longer shelf life than crystal sugar and a sweeter taste. It is found in many commercial food products including cereal, granola bars, toffee, candies, gums and baked goods.

Sugar alcohols: Sugar alcohols are low-calorie alternative sweeteners that have a lower glycemic index than table sugar and will not raise your blood sugar as rapidly. You find them in sugar-free candy and baked goods with names like maltitol, xylitol and sorbitol. These sugar alcohols aren't actually sugar or alcohol, but some are extracted from plants (sorbitol from corn syrup and mannitol from seaweed), but they are mostly manufactured from sugars and starches. They taste similar to sugar yet not as sweet. Sugar alcohols aren’t absorbed by the body and they don’t promote tooth decay, so they are frequently found in chewing gum and diet candies. “The big drawback of sugar alcohols is that many people experience bloating and gas,” says Begun.

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