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Troubles with Fructose?

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What is wrong with fructose?  Is it bad for you?  Fructose is becoming ubiquitous in our diets due to the widespread use of high fructose corn syrup (HFCS) in soft drinks as well as other processed foods.  For example, a cup of chopped tomatoes has 2.5 grams of fructose, a super-size soda has about 62 grams.  HFCS is made up of 55% fructose and 45% glucose.  It has become so incredibly inexpensive and abundant, partly due to corn subsidies in the U.S.  Sucrose (table sugar) use is also prevalent in the American diet  and is chemically a combination of glucose and fructose in a 1:1 ratio. Now, a new “natural sweeter” such as SUSTA contains fructose as its second ingredient, although this product has not yet been available for widespread use.  Do we need any more fructose?

In the early 1800’s and 1900’s, the average American took in about 15 grams of fructose (about ½ an ounce), mostly from fruits and vegetables.  Today we average 55 grams per day (73 grams for adolescents). Fructose is alleged to help contribute to the epidemics of obesity and associated diabetes so prevalent the United States and the world and is implicated in the a new condition called nonalcoholic fatty liver disease now affecting up to one-third of Americans.

All body cells can use glucose for energy, but only liver cells break down fructose.  End products can result in the formation of triglycerides, uric acid and free radicals.  The triglycerides may build up and cause liver damage.  When triglycerides get to the bloodstream, they can contribute to atherosclerosis in artery walls as plaque.  Uric acid decreases the production of nitric oxide that helps to protect artery walls; free radicals can damage cells, enzymes and DNA.  High fructose intake can help contribute to insulin resistance.

“There has been a remarkable increase in consumption of high-fructose corn syrup,” said Gerald Shulman of Yale University School of Medicine. “Fructose is much more readily metabolized to fat in the liver than glucose is and in the process can lead to nonalcoholic fatty liver disease,” he continued.  NAFLD in turn leads to hepatic insulin resistance and type II diabetes.

The small amount of fructose found in fruits, vegetables, and honey is not a bad thing.  But to sum it all up- too much fructose is bad for three main reasons:

  1. High blood triglycerides are a risk factor for heart disease.
  2. Fructose ends up circumventing the normal appetite signaling system so the regulation of appetite hormones can be out of balance.  This may help to explain why excess fructose in the diet is associated with weight gain.
  3. There is growing evidence that excess fructose consumption may contribute to insulin resistance leading to diabetes type 2 and thus a higher risk of heart disease.

Most studies on the effects of fructose metabolism have been animal studies and there have been no human clinical studies.

A recent study entitled “Consumption of fructose and high fructose corn syrup increase postprandial triglyceride, LDL-cholesterol, and apolipoprotein-B in young men and women” appears in the October 2011 issue of Journal of Clinical Endocrinology & Metabolism.

Researchers examined 48 adults aged 18-40 years old to compare the effects of consuming 25% of one’s daily calorie requirement as glucose, fructose, or high fructose corn syrup.  Within two weeks, the people consuming fructose or HFCS, but not glucose, had increased blood levels of LDL-cholesterol, triglycerides, and apolipoprotein B (a protein that can increase the risk of atherosclerosis

Today, almost all packaged foods have sugar added in some form (read nutrition and ingredient labels and you will soon realize the extent of its presence). Sugar had invaded virtually every processed food including ketchup, mayonnaise, and tomato sauce.  Just eat it in the form our grandparents ate it: fresh fruit.

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One thought on “Troubles with Fructose?

  1. Pingback: The Temptation of Eve « PaleoWorks

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