A research team from the University of Washington (UW) recently published a study in Physiology & Behavior revealing that moderate consumption of fructose- and high fructose corn syrup-sweetened beverages leads to significant alterations of lipid metabolization in the liver. Conducted on rats, the study also noted marked increases in both cholesterol and triglyceride levels in rats that fed on fructose-sweetened beverages.

Fructose is a monosaccharide sugar that is found in various fruits. It is a simple sugar that is often promoted as being a healthy "fruit" sugar, however the reality is that fructose is just one component of the complex sugar composition that occurs naturally in fruit. Most granulated fructose available today, called crystalline fructose, is derived from fructose-enriched corn syrup.

Similarly, high fructose corn syrup is a fructose-enriched form of highly-processed corn syrup that is commonly found in soda, ketchup, candy, dressings, and many other processed foods. The biggest concern about fructose is the fact that, unlike sucrose, it passes undigested through the small intestine where it enters the portal vein and heads directly to the liver.

In the context of the UW study, rats whose water had been sweetened with some form of fructose experienced substantial increases in the liver enzyme alanine aminotransferase, an enzyme that typically indicates the onset of liver damage or disease. Since fructose is not regulated by insulin and does not serve the body by producing energy, it can place a large burden on the liver while contributing to obesity.

Metabolic syndrome, also called "Syndrome X", is a condition related directly to the effects of fructose on the body. Obesity, improper insulin metabolism, and hypertension are all characteristics of this disease that typically result in the development of type 2 diabetes and cardiovascular disease. All such symptoms were observed in the rats during the study.

Researchers note that they intentionally studied realistic, moderate intakes of fructose by the rats that paralleled the average human intake of fructose-sweetened beverages and foods. It didn't take much fructose to have a significant impact on the health of the rats, adding more proof that fructose and high fructose corn syrup are directly implicated in the development of diabetes and obesity.

Researchers also looked at natural stevia extract in their study and no demonstrable negative effects were observed. Stevia is a safe, natural extract that contains no sugar and is up to 300 times sweeter than sugar per volume. It has a glycemic index of zero and is safe for diabetics.