When you bite into a juicy apple, the sweetness comes from fructose, a simple sugar that occurs naturally in most fruits and honey. Fructose's sweetness accounts for its popularity in processed foods. In 2004, high-fructose corn syrup accounted for 40 percent of all caloric sweeteners additives, notes the Institute for Agriculture and Trade Policy. The human body metabolizes fructose in a different way to glucose. Some people may even struggle to metabolize fructose at all.
Fructose Metabolism
Fructose metabolism in the human body is different to the metabolism of other forms of carbohydrates, according to researchers at the University of Illinois. Instead of being broken down into glucose for energy use or storage throughout the body, fructose metabolism mainly occurs in the liver. This process is more likely to produce fat. However, this doesn't seem to apply so much with sucrose -- a combination of glucose and fructose. Sucrose is the chemical name for the white sugar substance you find in kitchens all across America.
Negative Effects
When fructose breaks down in the liver, triglyceride forms, which is a type of fat, along with uric acid and particles known as free radicals. The Harvard Health Letter points out that all three have negative effects in the body. Free radicals can cause cell damage, while triglycerides can stick to artery walls or build up in the liver, contributing to a condition known as non-alcoholic fatty liver disease. Uric acid can turn off production of nitric oxide, which helps protect artery walls from damage. These effects are more likely when you consume large amounts of concentrated fructose, not simply by eating fruit each day.
Obesity Link
In an article published in April 2004 in the "American Journal of Clinical Nutrition," researchers linked the consumption of high-fructose corn syrup with rising obesity levels. In a population-based study, researchers noted that consumption of high fructose corn syrup increased by over 1,000 percent from 1970 to 1990, more than any other food substance. At the same time, overall obesity levels increased. They concluded that a diet high in refined fructose syrup is likely to lead to a greater chance of obesity. Like glucose, an excess of fructose also appears to increase insulin resistance, something that can lead to diabetes over time.
Hereditary Fructose Intolerance
An inability to break fructose down in the human body is known as hereditary fructose intolerance. It occurs when you don't have the protein needed to metabolize fructose. It can lead to dangerous fatty buildup in the liver. Early signs of fructose intolerance in babies include convulsions, jaundice and excessive vomiting. Your doctor can diagnose the condition, but treatment is mainly based around changing your diet to avoid fructose altogether.
References
- Georgia State University Department of Physics and Astronomy: Glucose
- MedlinePlus; Hereditary Fructose Intolerance; May 2011
- "American Journal of Clinical Nutrition"; Consumption of High-fructose Corn Syrup in Beverages May Play a Role in the Epidemic of Obesity; Bray G.A., et al.; April 2004
- University of Illinois At Urbana-Champaign; U of I Study: Fructose Metabolism More Complicated than Was Thought; Manabu Nakamura; December 2008
- News At Princeton: A Sweet Problem: Princeton Researchers Find that High-fructose Corn Syrup Prompts Considerably More Weight Gain; Hilary Parker; March 2010
- Harvard Health Publications; Is Fructose Bad For You?; P.J. Skerrett; April 2011
- Institute for Agriculture and Trade Policy; Not So Sweet: Missing Mercury and High Fructose Corn Syrup; David Wallinga, M.D.; Jan. 2009
