Fructose – a deadly sugar (sometimes)

Fructose is a simple sugar.

Carbohydrates are the primary type of nutrients used by the body for energy. Here is a chart representing carbohydrate sugars. Notice that fructose is identified as a yellow oval.

Carb Chemistry

Steve’s illustration of carbohydrate chemistry. Each sugar is represented by an oval – glucose is red, fructose is yellow and galactose is blue. When the simple sugars are combined, they make other sugars, starch, fiber and cellulose.

When these carbohydrates are digested, they are broken down into the simple sugars. Glucose is used by every cell in the body for energy. Galactose goes to the liver and in a very simple process, it is changed to glucose and sent back out in the bloodstream to be used for energy. However, fructose cannot be burned for energy. In fact, no cell in the body has any receptors for fructose. It all has to be metabolized into something else that can be used. One hundred percent (100%) goes to the liver.

Fructose is a Toxin

Fructose is a toxin in its pure state. The liver can handle small amounts of this sugar without becoming diseased. However, when large quantities are eaten it causes fatty liver disease, non-alcoholic cirrhosis and liver cancer. It cannot get out of the liver without the use of hormones. This places a heavy burden on the liver.

When Fructose is Metabolized in the Liver:

  1. Approximately 40% is converted into glucose and returned into circulation in the blood stream where it can be used by any cell in the body.
  2. Thirty percent (30%) is converted into bad cholesterol (VLDL).
  3. The remaining 30% follows multiple metabolic pathways.
  • Some is made into fat that goes to the muscle cells where it gums up the locks and causes insulin resistance.
  • Other is made into fat which remains in the liver as globules of fat causing a fatty liver, and causes liver insulin resistance.
  • Some of the fat is converted to triglycerides, or free floating fat in the blood. This also results in increased insulin resistance which causes elevated insulin levels and high blood pressure.
  • A portion is converted into uric acid.

A common disorder that is caused from high uric acid levels is gout. This is caused by an accumulation of uric acid crystals in the joints resulting in severe pain. Elevated uric acid levels will also cause a drop in nitric oxide levels, resulting in high blood pressure. A side effect of the above reactions involves the production of high levels of free radicals—substances that cause a lot of inflammation in the body, resulting in cardiovascular disease, organ and nerve damage and premature aging.

The ultimate end product of all these processes is increased insulin resistance.

Fructose in Food

Fresh fruit which includes fructose

Fresh from the tree loaded with vitamins, minerals and fiber.

Fructose is found in fruit and some root vegetables. It is also in most processed foods in the form of high fructose corn syrup. You may wonder about fructose being bad for you when it is found in fruit. Dr. Robert Lustig says that when God packages a toxin in your food, he always packages it with the antidote. The antidote for fructose is fiber. When you eat foods as they are packaged in nature, you do not have to worry about getting too much fructose. Those foods come packaged with fiber. Therefore, it is wise to avoid those foods that contain ingredients that have had the fiber removed. This would include processed foods, sugary foods, and even limit your intake of fruit juices. Choose to eat the whole foods instead.

Eating too much fructose stimulates fat production in the liver and pancreas. Its increased use is a primary cause of our diabetes epidemic today.  As bad as this all sounds, it does not mean that we should avoid fructose at all costs. When you eat foods that contain fructose, eat them with the fiber. Definitely avoid frequent use of sugar sweetened drinks, candies, desserts and processed foods. Eating it daily or many times a day will result in inflammation which will make you sick.

Here’s a great link to video by Dr. Lustig, Robert (2009, July 27). Sugar: the bitter truth.

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