Negative Side Effects of Consuming High Fructose Corn Syrup

Content provided by the Faculty of the Harvard Medical School

Negative Side Effects of Consuming High Fructose Corn Syrup

Question:

Why is high fructose corn syrup associated with so many harmful side effects?

Answer:

High-fructose corn syrup is in a huge number of processed foods. It adds a lot of calories, so it can contribute to obesity. But when eaten in moderation, this sweetener presents no special concern. However, recent evidence suggests that a large amount of fructose in your diet might alter your metabolism in a way that increases your risk for diabetes.

A series of chemical reactions changes fructose into glucose. During these reactions, fructose uses up a valuable resource in our body called "ATP" (adenosine-5-triphosphate). ATP fuels many reactions and helps deliver oxygen to your tissues. Without ATP, many functions in the body come to a standstill.

You can eat and drink a small amount of fructose without running your body low on ATP. But when you have a lot of fructose in your diet, the reaction that changes fructose depletes your ATP. This puts the body in a stressed state. This stressed state triggers resistance to insulin, especially in liver and fat cells. Insulin resistance is responsible for causing type 2 diabetes.

In addition to insulin resistance, depleted ATP has been blamed for other problems. High triglycerides, fatty liver, high blood pressure, artery disease, kidney troubles and high uric acid levels have all been tied to the stress of low ATP, and to high fructose.

Many of these problems are part of the so-called "metabolic syndrome." This is a cluster of health issues that tend to occur in the same person. It makes a person's risk for heart attack extremely high. Doctors don't completely understand what causes metabolic syndrome. Fructose has not been proven to be the source, but it is one likely suspect.

If this is true, it is a good reason for us to limit high-fructose corn syrup and other sweeteners. Table sugar (sucrose), honey, brown sugar, and molasses contain 50% fructose. High-fructose corn syrup is about 55% fructose.

Studies of diet habits give the "fructose theory" some teeth. In a study of more than 6,000 people (the Framingham Heart Study), people who drank at least one soft drink (soda, pop) each day had a higher risk for developing metabolic syndrome compared with people who did not often have a soft drink. Some scientists think the main culprit is the high-fructose corn syrup sweetener in these drinks.

There also appears to be a strong association between soft drinks and type 2 diabetes. The Nurses' Health Study followed more than 50,000 American women over an eight-year stretch. Women who had one or more sugary drinks a day were almost twice as likely to develop diabetes as women who did not have this habit. The soda drinkers also were about 10 pounds heavier than those who didn't drink soda.

Mary Pickett, M.D., is a lecturer for Harvard Medical School and an assistant professor of medicine at Oregon Health & Science University in Portland, OR. At OHSU, she practices general internal medicine and teaches medical residents and students.

Last updated:	July 20, 2009