Fructose, a sugar widely used in the form of high-fructose corn syrup, is in the news again this week. The findings are very important for all of us -- according to Consumer Reports, the use of fructose as a processed sugar increased 1,000 percent between 1970 and 1990, while the Illinois Farm Bureau reported that the average American consumed about 35.7 pounds of high-fructose corn syrup in 2009. However, before you cut your daily apple from you diet, it's important to understand that the fructose found in processed food is just that ... processed! It's true, we are eating more of it and a large part of that increase comes from processed food.
Table sugar, called sucrose, is actually a molecule of fructose which is bound to a molecule of glucose. High-fructose corn syrup was developed as a cheaper alternative to sucrose and contains a higher amount of fructose than glucose. After eating food with high-fructose corn syrup, the glucose is absorbed into the bloodstream and, with the help of insulin, moves into fat and muscle tissues. However, most of the fructose goes straight to the liver, where it increases the production of triglycerides. The triglycerides then move into the bloodstream as lipoproteins with cholesterol. This increase of triglycerides in the liver can lead to nonalcoholic fatty liver disease, a growing metabolic problem that affects about 10 percent of children and as many as a third of all adults. This metabolic problem occurs at the same time as insulin resistance, a precursor to type 2 diabetes, and it is considered a serious risk factor for heart disease.
A new study from Harvard Medical School, which was published in Molecular Metabolism
, found that fructose may encourage obesity and diabetes by overstimulating a hormone -- the fibroblast growth factor 21 (FGF21) -- that helps regulate fat deposits. The hormone rises sharply in response to eating fructose, with the largest rise of the hormone in people who were already obese. The study included twenty-one adults, half were lean and healthy, half were obese with high risks for developing diabetes. Participants were given pure glucose, pure fructose or a common mixutre on different mornings, their blood sugars were then measured over the next five hours.
The results? The study found that glucose has minimal impact on FGF21, while fructose increases FGF21 levels -- with the largest dose increasing hormone levels an average of four times within two hours of consumption! That's quite a spike!
But don't throw out those apples! The fiber in fruit actually hampers a sudden change of sugar levels. And we're not talking just any fiber! Fruit fiber provides the most protection when the cell walls that hold the fructose are whole, releasing the fructose slowly as the fiber in the fruit is digested, cutting the chance of a spike in blood sugar levels!
We haven't even mentioned all the great nutrients from fresh fruit!