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High-Fructose Corn Syrup’s Health Risks Remain Sticky

The need for a long-term study hinders what we know about high-fructose corn syrup.
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High-fructose corn syrup generally gets a bad rap by the health community. The sweetener has been blamed for everything from obesity to diabetes, heart attack to stroke. But what do we really know about it?

During the 1970s, the American food industry introduced high-fructose corn syrup, or HFCS, as a sweet substitute for sucrose (which we recognize as table sugar). Processed from corn — it gets its “high-fructose” name because its fructose content is higher than the corn from which it originates — the syrup contains about the same number of calories as sucrose or honey but has a greater shelf life. It’s also far cheaper than sugar, which has helped beverage manufacturers keep prices low.

The additional shelf life was a boon for processed foods, and, as a result, HFCS can now be found in just about every packaged item in the grocery store. From cookies to bagels, it’s nearly replaced sucrose in sweetened goods, although its real forte has been in liquids: Nearly two-thirds of all HFCS in the United States are found in beverages, namely soda.

(There are two types of the sweetener: HFCS-55, composed of 55 percent fructose, 42 percent glucose and 3 percent glucose polymers, used in soft drinks, and HFCS-42, which is 42 percent fructose, 53 percent glucose, and 5 percent glucose polymers, used in baked and processed goods.)

Although sugar’s availability has increased in the U.S. food supply since HFCS was introduced, the growth of corn sweetener is proportional to the growth in food supply.

That ubiquity has come at a price, and now having been vilified by the health conscious community as a source of obesity, diabetes and a slew of other problems, the Corn Refiners Association has lobbied to rename HFCS as “corn sugar” in an attempt to “enable consumers to easily identify added sugars in the diet.

Some products, such as Wheat Thins, Gatorade, Hunt's ketchup and Kraft salad dressings, no longer include HFCS as an ingredient in an effort to avoid the HFCS backlash. Even beverage manufacturers like Coca-Cola tout “imported” versions of their sodas from Mexico that use cane sugar and not HFCS.

Although making the change may work wonders for public relations, will replacing HFCS with sugar change consumers’ health?

During the last several years, scientists have had widely different results in testing whether HFCS reacts differently in the body compared to sucrose. Some researchers suggest there’s something special about HFCS that fosters obesity and the rapid weight gain and health failures of Americans during the last few decades.

A 2004 study postulated that fructose does not stimulate insulin production or enhance leptin production, unlike its cousin glucose, which is naturally found in fruit. Leptin and insulin are key hormones in the regulation of appetite and metabolism. Authors at Louisiana State University’s Pennington Biomedical Research Center, led by George Bray, reported that “because insulin and leptin act as key afferent signals in the regulation of food intake and body weight, this suggests that dietary fructose may contribute to increased energy intake and weight gain.” In short, the more HFCS you consume, the more HFCS you may want to eat.

Thus, “the increase in consumption of HFCS has a temporal relation to the epidemic of obesity, and the overconsumption of HFCS in calorically sweetened beverages may play a role in the epidemic of obesity.”

Another study found that when people were given HFCS-sweetened beverages, they gained significantly more weight than when they consumed the sugar (in the form of jelly beans). While jelly beans aren’t exactly a key component of a balanced meal, the study demonstrates people are generally more aware of the calories they eat rather than those they drink.

In a study by Princeton researchers last year, psychology professor Bart Hoebel noticed a disturbing trend in HFCS consumption. “When rats are drinking high-fructose corn syrup at levels well below those in soda pop, they're becoming obese — every single one, across the board. Even when rats are fed a high-fat diet, you don't see this; they don't all gain extra weight.”

Why? Nicole Avena, assistant research professor at the University of Florida who collaborated with Hoebel on HFCS research, said that although HFCS and sucrose are chemically similar, the greater amount of fructose found in HFCS could lead to considerable differences in the metabolic processes within the human body.

She explains the complicated process: “Fructose is absorbed further down the intestine than glucose, with much of the metabolism occurring in the liver. Fructose is metabolically broken down before it reaches the rate-limiting enzyme (phosphofructokinase), thereby supplying the body with an unregulated source of three-carbon molecules. These molecules are transformed into glycerol and fatty acids, which are eventually taken up by adipose tissue, leading to additional adiposity,” i.e. beer bellies and thunder thighs.

Circulating glucose, on the other hand, “increases insulin release from the pancreas.” Fructose does this less well because cells in the pancreas lack the fructose transporter.

Regardless, she added, “Too many calories, regardless of where they come from, can be detrimental to health and promote obesity.”

(Oddly enough, efforts to avoid calories may backfire. Consuming Splenda and other zero-calorie sweeteners may cause people to eat more than they normally would. Whether this is psychological, a person thinks they can over-consume calories because they saved 140 HFCS calories picking a Diet Coke over a Coca Cola, or a physiological response unique to a zero-calorie sweetener, is yet to be proven.)

But not all the research supports a malign role for corn syrup in the first place.

Stijn Soenen and Margriet S Westerterp-Plantenga at the University of Maastricht argue that “the replacement of sucrose with HFCS in beverages plays a causative role in obesity is not supported on the basis of its composition, biologic actions, or short-term effects on food intake.

In a study by the American Journal of Clinical Nutrition, participants’ insulin and blood sugar levels were measured upon eating food containing either HFCS or sucrose. The study's authors determined that “sucrose and HFCS do not have substantially different short-term effects on endocrine signals involved in body-weight regulation.” The way the body metabolizes HFCS and sucrose are similar enough that HFCS does not uniquely cause people to gain weight, compared to sugar.

The biggest issue with nailing down whether HFCS is a hero or villain is the lack of a long-term study. Because HFCS was only introduced into the diets of millions of Americans in the 1970s, scientists have not had enough time to determine whether HFCS is inherently good or inherently bad in the American diet.

Major roadblocks exist to producing long-term studies with definitive answers about HFCS's potential health risks. For a well-controlled study, participants would have to eat a highly restrictive diet controlling for the amount of HFCS in the diet, as well as other food groups to produce accurate results about how HFCS interacts in the body.

A nagging question remains: Consume HFCS freely or avoid it completely? Perhaps it is prudent to consider the foods in which HFCS is predominantly found: soda and processed foods. Both tend to be void of fiber, antioxidants and other key nutrients. Eating a diet rich in whole foods that limits both table sugar and HFCS may be the best nutritional bet.

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