We all know to limit our intake of sugar, but the most pressing, silent toxin is in fact fructose. Fructose is one of the most— universally prevalent ingredients in processed foods. Meanwhile, table sugar (i.e. sucrose) is composed of both glucose and fructose. Sugar as a whole has its negative effects on chronic diseases, but due to the alternative way our bodies metabolize fructose, fructose poses a greater risk.
Unlike glucose, fructose cannot be used by all body cells—only the liver. As the only organ that is capable of using fructose as energy, the liver’s energy stores are easily filled to capacity. Consequently, the energy that is not used is converted to fat. In short, calories no longer hold as much merit as we thought they did—the composition of calories influences energy metabolism more, thus making calorie quality a more important factor of obesity to consider.
Unfortunately, government subsidies have contributed to the shockingly large corn industry in the United States; due to subsidies, corn is widely available and cheap, which has promoted the prevalence of high fructose corn syrup in processed foods (as opposed to cane sugar or honey).
Links to chronic diseases
Dr. Robert H. Lustig (a Professor of Pediatrics at the University of California in San Francisco) is known for his hypothesis that refined fructose is the main contributor to the current obesity epidemic in the United States. He sources the origin of fructose in our diets to the late 1900s, when a fat-free craze was promoted by health professionals.
To provide context, fat in processed goods is an important ingredient that influences texture, taste, and structure. When it is taken out, a substitute is needed to compensate for the loss. High fructose corn syrup began to infiltrate the food industry to help with this compensation, and obesity levels sky-rocketed despite fat-free endeavors. Along with obesity, the prevalence of diabetes and nonalcoholic fatty liver disease rose with the increasing usage of high fructose corn syrup.
As mentioned, fat build up results from unmetabolized fructose in the liver and can lead to non-alcoholic fatty liver disease. At the same time, insulin resistance—a key biomarker for type II diabetes—is likely to occur. Insulin resistance triggers the production of excess insulin, and high insulin levels block the action of leptin, which is a hormone that signals satiety to the brain. Non-functioning leptin promotes overeating and demotes energy metabolism. Furthermore, studies of bloodwork from obese individuals have found higher levels of leptin in the bloodstream. This domino effect caused by fructose ultimately plays a role in the current obesity epidemic, and in the rising population suffering from chronic diseases.
It is important to note that fruits contain fructose, but this form of fructose is not harmful! Fruits are rich in water and fiber, which reduce blood sugar spikes. Compared to processed goods, fruits contribute a minimal amount of fructose to your diet. What is of concern are foods containing added fructose, corn syrup, and high fructose corn syrup. Even infants of 6 months have been diagnosed with obesity—increased exposure a to formulas and beverages sweetened with high fructose corn syrup have been associated with rising infant obesity levels. Additionally, foods that are marketed towards children (including cereals, lunchables, breakfast pastries and bars, and Gatorade) are notoriously high in fructose. Further, keep in mind that fructose is found in loads of foods that you would never suspect—including medicine, pickles and yogurt.
A common criticism is that table sugar is equally harmful (or even more harmful) due to its chemical makeup—not only is it composed of fructose, but it contains glucose as well! However, given that fructose has dominated most food production factories due to availability and cheap costs, fructose is more widespread than regular table sugar, affirming the greater risk it poses to health.
Dr. Lustig—who first brought the concern of fructose to the forefront of science—is unable to fully explain the long-term effects of fructose because the introduction of its presence in our diets is comparatively recent. While professional research continues, we can all do our own research by simply reading ingredient labels and being more aware of the prevalence of this dangerous toxin in our diets.