The Foods That Contain Fructose

Fructose, also called fruit sugar, is a naturally occurring chemical that biochemists formally classify as a monosaccharide, meaning single sugar unit. Like all monosaccharides -- including glucose and the sugar galactose that's found in milk -- fructose consists of a ring structure composed of carbon, oxygen, and hydrogen. It may occur alone in nature, or may occur linked to other monosaccharides, as it is in table sugar. Fructose is slightly sweeter than table sugar and much sweeter than glucose.

Table Sugar-Sweetened Foods

There are many ways to sweeten foods by adding sugars and sugar-like compounds. At home, many individuals rely upon sucrose, or table sugar, to sweeten their food and drink. In some processed foods, particularly those attempting to appeal to health-conscious individuals, added sugar comes from sugar beet or sugar cane, and these are also sources of sucrose. Sucrose is a disaccharide, meaning it's made up of two sugar units--specifically, sucrose is made up of glucose and fructose. As such, explain Drs. Reginald Garrett and Charles Grisham in their book "Biochemistry," any table sugar-sweetened foods or cane sugar-sweetened foods are sources of fructose.

Fruit

As plants produce energy by harvesting sunlight and using it to react carbon dioxide with water, they generate sugars, including glucose and fructose. Fruit, in particular, concentrates fructose to provide nutrition for a germinating seed. Fruits are natural sources of concentrated fructose, explain Drs. Mary Campbell and Shawn Farrell in their book "Biochemistry."

High Fructose Corn Syrup

Many processed foods are sweetened with high fructose corn syrup, which has a sweetness similar to that of table sugar, note Garrett and Grisham. The syrup is produced by chemically digesting starch, which does not taste sweet, from corn. As starch is digested, it breaks into individual molecules of glucose, similar to fructose. Using an enzyme called invertase, processing plants can convert some of the glucose in corn syrup into fructose. This sweetens the syrup and makes it roughly equivalent in sweetness to table sugar. From a chemically perspective, however, there are differences between corn syrup and table sugar -- glucose and fructose molecules in corn syrup aren't chemically combined, and the sugar molecules in sucrose are.