Doctors investigate not-so-sweet side of fructose

More and more people have become aware of the dangers of excessive fructose in diet. A new review on fructose in a recent issue of the Journal of the American Society of Nephrology(JASN) indicates just how dangerous this simple sugar may be.

Richard J. Johnson, M.D., F.A.C.P., and Takahiko Nakagawa, M.D., Ph.D., at the University of Colorado School of Medicine, provide a concise overview of recent clinical and experimental studies to understand how excessive amounts of fructose, present in added sugars, may play a role in high blood pressure, diabetes, obesity and chronic kidney disease (CKD).

Dietary fructose is present primarily in added dietary sugars, honey and fruit. Americans most frequently ingest fructose from sucrose, a disaccharide containing 50 percent fructose and 50 percent glucose bonded together, and high fructose corn syrup (HFCS), a mixture of free fructose and free glucose, usually in a 55/45 proportion. With the introduction of HFCS in the 1970s, an increased intake of fructose has occurred and obesity rates have risen simultaneously.

The link between excessive intake of fructose and metabolic syndrome is becoming increasingly established. However, in this review of the literature, the authors conclude that there is also increasing evidence that fructose may play a role in hypertension and renal disease.

"Science shows us there is a potentially negative impact of excessive amounts of sugar and high fructose corn syrup on cardiovascular and kidney health," Johnson said. "Excessive fructose intake could be viewed as an increasingly risky food and beverage additive."

Concerned that physicians may be overlooking this health problem when advising CKD patients to follow a low-protein diet, Johnson and Nakagawa recommend that low-protein diets include an attempt to restrict added sugars containing fructose.

Johnson and Nakagawa are listed as inventors on several patent applications related to lowering uric acid for the treatment or prevention of hypertension, diabetes and fatty liver. Johnson also has published a book, "The Sugar Fix," which covers this topic for the general public.

The article, titled "The Effect of Fructose on Renal Biology and Disease," appears online athttp://jasn.asnjournals.org.