HFCS 101: The Biology of High Fructose Corn Syrup

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biology high fructose corn syrup

High-fructose corn syrup (HFCS) is a commonly used sweetener found in a variety of processed foods and beverages. HFCS is made by first producing corn starch (a flour-like substance from corn), then processing it to turn it into a very sweet syrup. The processing of corn converts glucose into fructose, making it more concentrated than regular table sugar. But, sucrose (sugar) and HFCS actually have the about the same ratio of fructose to glucose, making them molecularly relatively similar.  Even so, HFCS can have a notably different impact on your system.

The History Of HFCS

HFCS was first invented in 1957, but did not start to be mass produced and put into food in the United States until the late 1970s. HFCS has replaced sucrose (sugar) as the primary sweetener in many foods over the last 20 years. It is now found in a variety of processed foods form bread, sodas, yogurt, etc. Granulated sugar, made from beets or sugarcane, is problematic when adding it to foods, especially beverages, because it is not in a liquid form. It will separate into granules in any sort of acidic liquid and cola is highly acidic. Since HFCS is in a liquid (syrup) form already, it has become an ideal sweetener to be added to drinks or food because it does not pose the same problem as granulated sugar. Corn is also a subsidized crop making it significantly cheaper to grow than beets or sugar cane.

The Dangers of HFCS

Many critics of HFCS believe it is dangerous to human health because it is a highly processed and concentrated sweetener. In 2004, Bray et al published a study where they connected the invention of HFCS (and the addition of it to 1000s of processed food products) to the increasing obesity rates over in the United States over the last 50 years. Other researchers have demonstrated, through various animal studies that consumption of HFCS may increase appetite leading to overeating and weight gain. One particular study on rats compared food with added sucrose to foods with HFCS. Rats who received the food with the HFCS showed 48% more weight gain and symptoms of metabolic syndrome (high blood pressure, elevated blood sugar, and high cholesterol). There have been several studies on humans also that have shown that increased intake of HFCS has resulted in abdominal weight gain and elevated triglycerides (a fat found in the blood). The question is, why is HFCS so much worse for you, compared to, say, Organic Cane Sugar?  The answer lies largely in the difference between Glucose and Fructose.


Glucose is one of the three dietary monosaccharides that are absorbed directly into the bloodstream during digestion.  It is the primary energy source for most organisms, from bacteria to humans.  Glucose is also the primary source of energy for the brain, so it’s availability greatly influences mental processes. When glucose is low, mental processes requiring greater effort (self-control, higher level decision making) are impaired.  Glucose molecules are absorbed in the intestines.  Once glucose has entered the cells, insulin is released from the pancreas, it’s mission being to control the amount of and rate at which glucose is converted to fat. Another hormone that is released once glucose is detected is leptin.  Among leptin’s many jobs (like regulating energy intake and energy expenditure) is the managing of the body’s metabolism and appetite.  When glucose is sufficiently consumed, leptin is released, telling your brain that your body has eaten enough.


Fructose, unlike glucose, is processed in a pathway independent of insulin.  It is actually absorbed by a different transporter in the body (Glut-5) that is not controlled by insulin.  Once fructose is in the blood, it becomes very difficult for the body to regulate it’s absorption.  Not only is fructose poorly regulated by the body, but it also helps create insulin resistance, where cells stop responding to insulin’s messages about glucose absorption.  The more serious this becomes, the greater a person’s chances of contracting Type 2 Diabetes. Not only is insulin not released when fructose is consumed, but neither is leptin.  This lack of leptin means your brain never receives the signal that you have eaten enough, so you will keep on eating. Thus, the addition of HFCS to food does allow for a higher consumption of fructose than is generally found in less processed diets.  Though the obesity epidemic cannot be linked to only one food item as there are many different variables that have contributed to it, highly sweetened foods, like soda, which generally contain large amounts of HFCS, have provided additional calories in our diets.  If over-consumed, they can lead to obesity.  Too many calories equal weight gain, no matter where those calories are coming from.  Not only are excess calories a concern with HFCS, but so is it’s impact on insulin and leptin, two of the body’s greatest sugar regulators. The conclusion to the debate over HFCS versus sugar is very simple. Eat real food. Food should give you actual nutrients and vitamins. HFCS and sugar provide your body with many additional calories, but very little nutrition. Vegetables, lean protein, and healthy fats provide your body with the nutrients it really needs.