We’ve always known that sugar, as a source of empty calories, is not good for us. Some suspected that, in large amounts, it contributed to diabetes and heart disease. New research is showing that sugar, especially fructose, is worse than we thought.
Dr. Richard Johnson MD, a kidney disease researcher at the University of Colorado, published a book in 2008 called “The Sugar Fix – the High Fructose Fallout that is making you Fat and Sick”. The book is based on years of his research on the effects of fructose on the metabolic system in animals and humans.
Johnson originally focused his research on uric acid which he found was a significant factor in obesity, high blood pressure as well as kidney disease. At low levels uric acid is actually an important antioxidant, but at high concentrations it causes problems. The most well-known is gout – that painful arthritis that attacks the big toes. We knew that meats with a high purine amino acid content raises uric acid. What Johnson discovered to his surprise is that the simple sugar fructose is a strong promoter of uric acid.
Fructose is metabolized differently in the body. Laboratory animals fed a high fructose diet developed obesity, insulin resistance (which can lead to diabetes), fatty liver, high blood pressure, high triglycerides, kidney disease and vascular disease, while animals given the same calories as either dextrose or glucose did not.
Johnson noted a rise in these conditions in Americans over the past 20 years which coincides with the increase of added sugars in the typical American diet. One quarter of Americans now consume 180 lbs a year in added sugars. Is it a coincidence that one in four Americans are diabetic or pre-diabetic?
The most common sources of fructose are High Fructose Corn Syrup (HFCS) and sucrose. Even though HFCS is 55% fructose and sucrose is 50%, they are metabolized differently; an animal study found that HFCS increased fatty liver more than sucrose. HFCS is a very cheap food additive and is increasingly common in many processed foods. One of the highest sources of HFCS is soft drinks (keep in mind the sugar free “diet” pops with artificial sweeteners are no healthier). Fruit is not a significant source of fructose in the diet, but fruit juice can be.
A human trial with a high fructose diet caused an increase in hypertension. In a recent controlled clinical trial Johnson found that a low fructose diet significantly improved weight loss and blood pressure in overweight people.
Johnson found that the best way to benefit from a low fructose diet is to first eliminate it completely for two weeks. This allows your body to “reboot” after which you can tolerate small amounts. He suggests limiting fructose to 25g a day. To accomplish this you will need to eat mostly unprocessed foods and read labels carefully. It won’t be easy – a lab study found that, at least for rats, sugar was more addictive than cocaine – but your improved weight and health will make it worthwhile.
This article is intended for educational purposes only; for medical advice consult your licensed health practitioner.