03/03/2010High Frutose Corn Syrup, Blood Pressure, and Kidneys

Joel Topf, MD

In 1964, Walt Disney purchased the "It's a Small World" ride from the New York World's Fair. It became a staple of the American experience and became as beloved a part of Disneyland as mouse ears. I n 2007, the ride had to be refurbished, in part due to the increase in the average size of the passengers. The boats had been built for men weighing 175 pounds and women, 135 pounds.  The overloaded boats were now routinely running aground in shallow areas, delaying the ride and frustrating patrons.

While this seems to be an innocent anecdote on our expanding waist sizes it serves to remind us that we are different than we used to be. The diseases of today have not always been with us. Obesity is not the only disease of indulgence that newly plagues us. Diabetes and hypertension were both rare diseases at the beginning of the twentieth century. Hypertension used to occur in 6% of adults; it now attacks a third. Diabetes was a one in a thousand diagnosis, now it is found in 1/5th of hospital admissions.

These three diseases; obesity, diabetes and hypertension, lie near the origin of the major health challenges facing our civilization. One explanation of why these diseases emerged in the last 100 years is the fundamental change in our diet: A dramatic increase in the amount of sugar we eat. In 1700 Europeans ate a pound of sugar a year. Americans now eat 80 pounds a year.

Table sugar, sucrose, is a disaccharide, which means it is made from binding two simple sugars together: One molecule of glucose and one of fructose. Glucose is the simple sugar our body is tuned to use. The carbohydrates found in breast milk, lactose, is 50% glucose. E very tissue of the body is able to turn glucose into energy; in fact, glucose is the only carbohydrate the brain can use as a fuel supply. The other half of sucrose, fructose, is less useful than glucose. It is only metabolized in the liver. Glucose metabolism is a tightly regimented, stepwise process. Meticulous control is maintained over the breakdown of glucose at three separate steps in its initial metabolism.

Fructose, on-the-other-hand, enters the liver and is consumed as fast as possible. The liver goes crazy over fructose and metabolizes it in a haphazard and unregulated process. Since the energy is produced without immediate need, a lot of the metabolic energy is directed into storage, which in the liver takes the form of triglycerides and fat. Fructose consumption leads to non-alcoholic fatty liver disease and has surpassed alcoholism as the number one cause of hepatitis.

The fructose consumption also increases the production of uric acid and raises serum uric acid level. W hile classically, uric acid is associated with gout, it is increasingly being accepted as a cause of chronic kidney disease and hypertension. Fructose appears toxic and we are eating more than ever.  But there is a general confusion about the source of fructose in our diet. High fructose corn syrup was introduced in the 1960's and has increased from non-existent in the food supply to average annual consumption of about 40 lbs a year. High Fructose Corn Syrup (HFCS) replaced sucrose in both Pepsi and Coke in 1984. HFCS is largely found in two varieties: HFCS 42 and HFCS 55. The number indicates the percent of which is fructose, 42% in the former and 55% in the latter.

Regardless of which variety of HFCS one encounters, they all have roughly the same amount of fructose as common table sugar. Despite the scary sounding name, HFCS does not contain any more fructose than your sugar bowl. W e are eating more fructose than ever but it not because of HFCS, it is because we love sweets.

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