Corn Fructose

There is a lot of confusion about fructose. Much marketing has been done to make us believe that "fructose is the sugar (singular) in fruit" and therefore it is healthy.

In fact, there are many sugars (plural) in fruit including galactose, glucose, dextrose, sucrose, levulose, maltose, and others. These are metabolized in the human body into blood glucose.

In a fresh, whole fruit, these sugars occur along with a lot of water, fiber, antioxidants, vitamins, minerals and other trace nutrients, beneficial plant sterols, and other co-factors that contribute to their usefulness and metabolism. Fruit itself is a natural and healthy food.

Fructose is NOT a type of naturally occurring sugar found in fruit, but is rather the name for a manufactured version of the simple sugar 'levulose', found in many foods including honey, tree fruits, berries, melons, and some root vegetables, such as beets, sweet potatoes, parsnips, and onions, usually in combination with sucrose and glucose. Fructose is made in factories from the starch in corn. It was developed by Japanese food scientists in 1971 as a cheap replacement for cane sugar, and called "high fructose corn syrup." It is sold as "crystalline fructose" in natural food stores. High fructose corn syrup is now the standard sweetener used in mainstream processed foods as well as many "natural" and "healthy" foods, including natural soft drinks, chewable and dissolvable vitamins, and protein powders.

According to the book Fat Land: How Americans Became the Fattest People in the World, from the beginning fructose was known to have a problem:

"Fructose, unlike sucrose or dextrose, took a decidedly different route into the human metabolism. Where the latter would go through a complex breakdown process before arriving in the human liver, [fructose], for some reason, bypassed that breakdown and arrived almost completely intact in the liver, whereupon the organ set upon it as it would anything else. This unique feature of fructose, which was intensified by the high concentrations...would come to be called 'matabolic shunting'. In food science circles, it raised eyebrows...but no one really looked at it in depth...

Eventually, cell biologists figured out that fructose was being used in the liver as a building block of triglycerides. This it did by mimicking insulin's ability to cause the liver to release fatty acids into the blood stream...Bombarded by fatty acids, muscle tissue develops insulin resistance.

Whether humans consume enough high-fructose syrup to activate the effect was something that eluded scientists until the year 2000, when researchers at the University of Toronto in Canada fed a high-fructose diet to Syrian golden hamsters, which have a fat metabolism remarkably similar to that of humans. In weeks, the hamsters developed high triglyceride levels and insulin resistance.

The book goes on to describe a human study in which two dozen healthy volunteers were fed a diet that derived 17 percent of total calories from fructose (the percentage believed by the researchers to be consumed by the average American). Blood measurements were taken for fats and sugars, then the volunteers were switched to a diet sweetened with sucrose. "The results were dramatic. The fructose diet produced significantly higher triglycerides in the blood--in men about 32 percent higher--than the sucrose-sweetened diet."

Triglycerides, of course, in the blood stream trigger LDL or bad cholesterol, which leads to heart disease.

Another interesting study on fructose was done by a team of investigators at the USDA, led by Dr. Meira Field. Sucrose (as in cane sugar) is composed of glucose and fructose. When sugar was given to rats in the study in high amounts, they developed multiple health problems, especially when the rats were deficient in certain nutrients.

The researchers wanted to know whether the fructose or the glucose was responsible for the problems. So they repeated their tests with two groups of rats--one given glucose only and the other given fructose only. The results were clear. The glucose group was unaffected. The fructose group, however, had disastrous results: male rats did not reach adulthood, they had anemia, high cholesterol and their hearts enlarged until they exploded. They also had delayed testicular development. The female rats were not so affected, but they were unable to give birth to live offspring.

Dr. Field said, "Every cell in the body can metabolize glucose. However, all fructose must be metabolized in the liver. The livers of the rats on the high fructose diet looked like the livers of alcoholics, plugged with fat and cirrhotic."

For more on the health effects of fructose, see:

* "Fructose is No Answer for a Sweetener"

* The Murky World of High-Fructose Corn Syrup</a>

* The Double Danger of High Fructose Corn Syrup

* Fructose: Sweet, But Dangerous

* Fructose: Maybe Not So Natural...and Not So Safe

* Foods Filled With Fructose Can Lead to Overeating