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Naturally Occurring Fructose in Fruit vs Industrial Fructose

©Ori Hofmekler

Given the numerous questions we received about the consequences of having fructose in food, I’d like to put the record straight on this topic.

Fructose is a monosaccharide component of sugar. In whole fruits, fructose occurs naturally along with nutrients and fiber that allow proper digestion and utilization. In its industrial refined form however, it is far more toxic than sugar itself.

The human body evolved for whole fruit ingredients including naturally occurring fructose but not for refined equivalents such as industrial fructose.

When consumed in its industrial form, fructose messes with the whole metabolic system. Refined fructose bypasses the insulin response, and thereby devastates organs that are insulin dependent such as the liver (liver’s sugar metabolism is regulated by insulin).

Being insulin dependent, the liver (which is the main site of fructose metabolism) fails to utilize fructose and thus becomes virtually defenseless against fructose accumulation. Desperate to facilitate fructose clearance, it tends to convert it to lipids which are then dumped into the circulation, thereby causing elevated blood lipids along with progression of disorders associated with hyperlipidemia.

Excessive fructose consumption has been linked to fatty liver, elevated blood lipids, diabetes and obesity. The seemingly “low glycemic” fructose molecule is now one of the most sickening and fattening substances known to man.

Industrial fructose is also a major contributor to aging.

Being highly reactive with proteins in a process known as glycation (Maillard reaction), refined fructose induces aging of cells and tissues by forming a defected protein matrix called Advanced Glycation End Product (AGE). AGE formation is irreversible. As fructose consumption remains persistently high, AGE tends to accumulate and react with tissues and DNA, to further accelerate physiological aging.

Industrial fructose is available in the forms of crystalline fructose, high fructose syrup (HFS), derived primarily from corn, and agave syrup derived from the agave plant; all of which have sweetness levels that are higher or equivalent to that of sucrose.


  • Refined fructose is poorly absorbed by the gastrointestinal tract, and thus dumped almost entirely into the liver which tends to convert it into fat/triglycerides.
  • A direct link was found between high fructose consumption to elevated triacylglycerols and bad cholesterol (LDL & VLDL) associated with increased waist-to-hip ratio and progression of obesity.
  • High fructose intake by children has been reported to affect their future risk of cardiovascular disease.
  • The load of fructose per capita has been ever increasing in parallel with that of sugar. Continuing surveys of food intake report that the average person consumes about 80g added sugar per day, approximately half of which is fructose. People ranked in the top one-third of fructose consumers, ingest 137g added sugar per day; whereas those in the top 10% consume 178g per day, with half of that amount being fructose.
  • Though high in fructose, whole fruits have been an essential part of the human diet and are thus viable and tolerable. That’s due to the presence of naturally occurring insulin supportive nutrients in fruits such as polyphenols, indoles, essential acids and alkaloids, which altogether grant viable nourishment. Some stress response nutrients in fruits such as resveratrol and salicin have been shown to trigger metabolic pathways that not only support sugar utilization, but also counteract disease and aging http://www.defensenutrition.com/stress-activated-food/ The fiber content in whole fruits is another contributing factor to healthy sugar metabolism (unlike fruit juices which are typically void of fiber).

In Conclusion:

Being more toxic than sugar, refined industrial fructose turns extremely harmful when ingested in large amounts. Consumption of Crystalline Fructose and High Fructose Corn Syrup, has been linked to obesity, diabetes, dyslipidemia and fatty liver. Unlike industrial fructose, whole fruits’ fructose is safe and viable as a naturally occurring ingredient.


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About Ori Hofmekler — founder of Defense Nutrition and author of The Warrior Diet, is a nutritional and fitness expert. Follow him on Twitter, Facebook and Google+.