Fructose is the simple sugar found in fruit and honey. In its natural state, fructose is not considered a health concern. It becomes a concern when it is used to make table sugar and high fructose corn syrup (HFCS). HFCS is corn syrup (glucose) that has been enzymatically treated to change some of the glucose into fructose, making it sweeter for the same number of calories.
Metabolism of Fructose and Glucose
All carbohydrates are broken down by the body into the simple sugars, glucose, galactose and fructose. Sucrose (table sugar) is made from equal parts of glucose and fructose, whereas HFCS has a slightly higher fructose-to-glucose ratio.
All simple sugars and are metabolized in the liver. Once glucose has been metabolized by the liver, it is used for immediate energy or stored as glycogen in either the muscles or the liver. If glycogen stores are not used, then glucose will be turned into fat. Fructose, on the other hand, goes to the liver but it is solely converted to fat.
Fructose and Metabolic Syndrome
Fructose has come under attack as more research is linking a high fructose intake to obesity. A study published in the March 2010 edition of the "Journal of Pharmacology, Biochemistry and Behavior," reports ScienceDaily, concluded that rats given HFCS gained significantly more weight than those given table sugar. The rats on the HFCS rich diet had an abnormal weight gain, an increase in triglyceride levels and an increased amount of fat surrounding their abdomens. These are all characteristics typically seen with metabolic syndrome.
Fructose and Leptin
Leptin is a key hormone that helps regulate appetite. A diet high in fructose can result in the development of leptin resistance. This means that a high intake of fructose can hinder the leptin from telling the body that it is full, leading to overeating.
Fructose and Diabetes
Fructose has been recommended for individuals suffering from diabetes due to its lower glycemic index compared to sucrose. This suggests that fructose doesn't raise the blood glucose levels as high as sucrose. New research emerging on this topic may be saying something different when it comes to fructose and blood glucose levels. University of Florida researchers published a report in the "European Journal of Nutrition," and reported by ScienceDaily, suggesting that consuming too much fructose, as in HFCS, causes uric acid levels in the body to increase. An increased level of uric acid in the blood is often linked with diabetes and can induce insulin resistance.
Fruits and Fructose Levels
Fructose, naturally found in fruit, certain vegetables and honey, is not the enemy. These foods are not off limits, it just means that large amounts of the fruit or vegetable should be avoided. Fruits and vegetables contain important nutrients such as fiber, vitamins, minerals and antioxidants. They should be an integral part of a healthy and balanced diet.
Foods to limit
People should be cautious of ingredients that include high fructose corn syrup and sucrose. One of the major sources of fructose in the American diet comes from soda. In addition, fructose can be found in baked goods, most processed foods, ketchup, and table sugar. If you are concerned about fructose in your diet, you should consult a dietitian or talk to your physician.
References
- Science Daily: High-Fructose Corn Syrup Prompts Considerably More Weight Gain, Researchers Find
- Science Daily: Fructose Sets Table For Weight Gain Without Warning
- American Journal of Clinical Nutrition: Consumption of High-Fructose Corn Syrup in Beverages May Play a Role in the Epidemic of Obesity
- Science Daily: Too Much Fructose Could Leave Dieters Sugar Shocked
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