High fructose is something nobody should consume too much of--yet many nutrition experts make too much of its harmfulness.

We Americans love to think in terms of good and evil. This binary, moralistic mindset even affects our understanding of food and nutrition. We delight in classifying food types, food components, and individual nutrients as either “good” or “evil”. Fiber, protein, and omega-3 fatty acids make the good list. Saturated fat, starch, and sugar are evil.

The reality is that there are no inherently good or evil nutrients. By their very definition, all nutrients have the capacity to nourish. Ingestible substances that do not have the capacity to nourish have another name: poisons.

It is possible to consume too much of any nutrient—even the “good” ones—or too little of any nutrient—even the “bad” ones. For example, it is possible to consume too much fiber. It is also possible to consume too little saturated fat. The nutrients we tend to classify as evil are simply those we tend to consume too much of rather than too little of.

High fructose corn syrup is currently one of the public’s favorite evil food compounds. It is not, in fact, a single nutrient but is instead a processed food compound comprising two simple sugars: fructose and glucose. Invented in the early 1970s as an inexpensive way to sweeten processed foods and beverages, high fructose corn syrup overtook America’s food supply like an invading army beginning in 1980. The average American now consumes more than 60 pounds of high fructose corn syrup each year.

The obesity epidemic that plagues our society also began to emerge in 1980 or thereabouts. This coincidence has led many nutrition experts and would-be experts to wonder whether high fructose corn syrup might be a major cause of our societal weight problem—or perhaps even the major cause. This speculation has led to widespread research into differences in how fructose and other sugars are metabolized and into the metabolic, hormonal, and other effects of high levels of fructose consumption.

It turns out that fructose is metabolized somewhat differently than other sugars, and that high levels of fructose consumption do have certain metabolic, hormonal, and other effects that result in fat storage and weight gain. These findings have led some nutrition experts to conclude that high fructose corn syrup is inherently fattening and a primary culprit in the obesity epidemic. Thanks to their influence, a large and growing portion of the general population today holds the same belief.

There is a fatal flaw in the logic of this conclusion, however. Any nutrient or food compound that is consumed in amounts many times greater than is natural is sure to have some type of negative effect on the body—whether that effect is weight gain or something else. And if you then investigate how that specific nutrient or food compound affects the body, both generally and when consumed in excess, you will surely identify one or more mechanisms that underlie the negative effect of excess. But once you have identified these mechanisms, it is wrong to conclude that you have isolated an inherent property of the nutrient that causes the negative health effect. You have merely determined how an excess of the nutrient in question results in an undesirable consequence.

This is precisely what has happened with high fructose corn syrup. Sixty pounds a year is way too much. It is only to be expected that this absurdly high level of consumption should cause at least one health problem—in this case weight gain. And it is only to be expected that high fructose corn syrup causes this effect through a slightly different physiological process than some other nutrient might cause the same effect when consumed in excess. But the essence of the problem is not that high fructose corn syrup is intrinsically more harmful (evil) than glucose, sucrose, or anything else for that matter. The essence of the problem is the 60 pounds!

There is no reason to believe that Americans would lose weight if all the high fructose corn syrup in every product that uses it were replaced with another form of sugar. There is every reason to believe we would lose weight if we ate less sugar altogether.

High Fructose Corn Syrup and Sports Drinks

Some sports drinks contain high fructose corn syrup, as do some sports energy gels and energy bars. Athletes tend to be more nutrition-conscious than the average person, so it’s no surprise that athletes often decry the use of high fructose corn syrup in sports drinks and other “ergogenic aids” and go out of their way to find and use products that do not contain it.

Two things need to be said about this phenomenon. First, ergogenic aids are not health foods. Their purpose is to improve athletic performance. They are designed to be used only immediately before, during, and after exercise and should only be used at these times. When used to fuel exercise, the sugars (of whatever kind) in ergogenic aids are broken down immediately to supply energy and are not stored as fat. But when consumed at other times, the sugars in ergogenic aids affect the body in the same way as those in a can of soda or a cupcake.

The important question regarding sugars in sports drinks and other ergogenic aids when used properly is not how they affect health but how they affect performance. Research has shown that, when consumed individually in solution, most simple sugars and high-glycemic carbohydrates—including glucose, sucrose, maltodextrin, and polylactate—have the same level of benefit. Fructose is actually a notable exception in that it tends to cause GI distress when consumed as the only carbohydrate in a sports drink of normal concentration.

However, a sports drink is more effective when fructose is added to a sports drink as a second carbohydrate. This was shown in a recent study conducted by Roy Jentjens from the University of Birmingham. Cyclists were given either a glucose solution or a combined glucose-fructose solution with the same total calories during a ride to exhaustion. The cyclists receiving the combined sugars burned 55 total more carbohydrate than those that received the glucose solution.

The reason fructose boosts total carbohydrate oxidation during exercise when included as a second carbohydrate is that, as mentioned above, it is processed by the body through different channels than other sugars. Thus, when, say, your body’s sucrose absorption channel is saturated by the sucrose contained in the sports drink you’re using, your fructose absorption channel remains available. Adding fructose to your sports drink allows you to exploit this additional carbohydrate absorption capacity and thereby absorb and use more total carbohydrate.

Thus, it is actually foolish to avoid sports drinks containing fructose or high fructose corn syrup. As long as one or two other high-glycemic carbohydrates (glucose, sucrose, maltodextrin, etc.) are listed ahead of fructose or high fructose corn syrup on the product label, a sports drink that contains some form of fructose is likely to perform better than one that does not.

Take-Home Lessons

· The average American consumes far too much high-fructose corn syrup.

· Consuming large amounts of any sugar promotes weight gain.

· A person who consumes high fructose corn syrup in moderation is no more likely to gain weight than a person who consumes none.

· There is no reason to selectively avoid processed foods and beverages containing high fructose corn syrup. Such foods tend to contain other nutrients and ingredients that we consume too much of and not to contain many nutrients we consume too little of. So consumption of processed foods and beverages should be minimized in general, for reasons that go far beyond high fructose corn syrup.

· The addition of high fructose corn syrup or fructose to a sports drink as a second (or third) carbohydrate enhances total carbohydrate oxidation during exercise.

- Sports drinks that contain high fructose corn syrup or fructose as a second (or third) carbohydrate are likely to perform better than those that do not.