Demand for sugar in the United States grew throughout the 20th century. But it skyrocketed when the food industry began mass producing high-fructose corn syrup (HFCS) in the 1970s. Though HFCS intake has fallen in the new millennium, researchers still struggle to understand how this hotly debated sweetener impacts our health.
Some sugars appear in nature. Table sugar (also known as sucrose, which is half fructose and half glucose) is derived from sugar beets and cane. Fructose is common in fruits and honey.
HFCS, on the other hand, is processed from corn kernels. Producers soak kernels to extract corn starch and then add enzymes, refining the naturally occurring glucose (a.k.a. dextrose) into a syrup that often contains high levels of fructose. (At its peak in 1999, 10 percent of America’s corn crop was being used to make HFCS, according to government figures.)
HFCS is frequently found in soft drinks, breakfast cereals and sauces like ketchup. It is cheaper than sugar (in part because America’s corn crop is government-subsidized) and does not conceal other flavors. Though the level of fructose in most HFCS is advertised as no more than 55 percent, researchers at the University of Southern California have found samples of Pepsi and Coca-Cola containing 65 percent fructose and believe we may be consuming far more fructose than we realize.
Since a landmark paper in 2004, many scientists have linked America’s obesity epidemic to our high HFCS intake. But, as the two sections of research below emphasize, scientists disagree on the role that added sugars play not just in obesity, but in related health concerns as well, such as type 2 diabetes and liver disease. Is the problem that Americans eat too much sugar generally? Or is HFCS more harmful than sugar? Like fructose, HFCS is metabolized in the liver — so is there a connection to liver disease?
Some scientists argue that the data is too limited to vilify HFCS or that many foods containing HFCS simply lack nutritional value. The American Medical Association, in its last public comment on the disagreement in 2008, declared that “there is insufficient evidence” to curb consumption of HFCS or merit placing warning labels on products containing HFCS.
But, affirm many of the papers below, subsequent evidence warrants caution.
In response to these growing concerns, the corn industry has actively championed HFCS. A 2013 commentary in the International Journal of Obesity, for example, condemns research on links between HFCS and health problems. Two of the authors had received funding from the Corn Refiners Association. That industry group, which defends HFCS as “nearly identical to table sugar” often lobbies the Food and Drug Administration (FDA), America’s food regulator, which calls the additive safe. The same group unsuccessfully petitioned the FDA in 2012 to change the name of HFCS to “corn sugar.”
Academic papers that find reasons for concern:
“Fructose Content in Popular Beverages Made with and Without High-Fructose Corn Syrup” Walker, Ryan W.; Dumke, Kelly A.; Goran, Michael I. Nutrition, 2014. DOI: 10.1016/j.nut.2014.04.003. Conclusion: “Our results provide evidence of higher than expected amounts of free fructose in some beverages. Popular beverages made with HFCS have a fructose-to-glucose ratio of approximately 60:40, and thus contain 50 percent more fructose than glucose. Some pure fruit juices have twice as much fructose as glucose. These findings suggest that beverages made with HFCS and some juices have a sugar profile very different than sucrose, in which amounts of fructose and glucose are equivalent. Current dietary analyses may underestimate actual fructose consumption.”
“An Assessment of the Relationship Between the High-Fructose Corn Syrup and the Soft Drink Markets in the United States” Kennedy, P. Lynn; Garcia-Fuentes, Pablo A. Working paper presented at the Southern Agricultural Economics Association annual meeting, 2017. Abstract: “This study analyzes the market of high fructose corn syrup (HFCS) in the United States and its linkages with soft drink market. […] The results show that soft drinks are the main driver behind the growing demand for HFCS. In addition, negative news on HFCS (the association of HFCS consumption and obesity) has a negative effect on the growth of demand for soft drinks; however, per capita advertising on soft drinks has a positive effect on the growth of demand for soft drinks and more than offsets the effect of negative news.”
“High-Fructose Corn Syrup-55 Consumption Alters Hepatic Lipid Metabolism and Promotes Triglyceride Accumulation” Mock, Kaitlin; et al. Journal of Nutritional Biochemistry, 2017. DOI: 10.1016/j.jnutbio.2016.09.010. Abstract: “High-fructose corn syrup-55 (HFCS-55) has been suggested to be more lipogenic than sucrose, which increases the risk for nonalcoholic fatty liver disease (NAFLD) and dyslipidemia. The study objectives were to determine the effects of drinking different sugar-sweetened solutions on hepatic gene expression in relation to liver fatty acid composition and risk of NAFLD. […] Results from gene expression and fatty acid composition analysis showed that, in a hypercaloric state, some types of sugars are more detrimental to the liver. Based on these preclinical study results, excess consumption of caloric sweetened beverage, particularly HFCS-sweetened beverages, should be limited.”
“Sugar Content of Popular Sweetened Beverages Based on Objective Laboratory Analysis: Focus on Fructose Content” Ventura, Emily E.; Davis, Jaimie N.; Goran, Michael I. Obesity, 2010. DOI: 10.1038/oby.2010.255. Abstract: “The consumption of fructose, largely in the form of high fructose corn syrup (HFCS), has risen over the past several decades and is thought to contribute negatively to metabolic health. However, the fructose content of foods and beverages produced with HFCS is not disclosed and estimates of fructose content are based on the common assumption that the HFCS used contains 55 percent fructose. The objective of this study was to conduct an objective laboratory analysis of the sugar content and composition in popular sugar-sweetened beverages with a particular focus on fructose content. […] Results showed that the total sugar content of the beverages ranged from 85 to 128 percent of what was listed on the food label. The mean fructose content in the HFCS used was 59 percent (range 47–65 percent) and several major brands appear to be produced with HFCS that is 65 percent fructose. Finally, the sugar profile analyses detected forms of sugar that were inconsistent with what was listed on the food labels. This analysis revealed significant deviations in sugar amount and composition relative to disclosures from producers. In addition, the tendency for use of HFCS that is higher in fructose could be contributing to higher fructose consumption than would otherwise be assumed.”
“High-Fructose Corn Syrup and Diabetes Prevalence: A Global Perspective” Goran, Michael I.; Ulijaszek, Stanley J.; Ventura, Emily E. Global Public Health, 2012. DOI: 10.1080/17441692.2012.736257. Abstract: “The overall aim of this study was to evaluate, from a global and ecological perspective, the relationships between availability of high fructose corn syrup (HFCS) and prevalence of type 2 diabetes. […] Diabetes prevalence was 20 percent higher in countries with higher availability of HFCS compared to countries with low availability, and these differences were retained or strengthened after adjusting for country-level estimates of body mass index (BMI), population and gross domestic product (adjusted diabetes prevalence=8.0 vs. 6.7 percent, p=0.03; fasting plasma glucose=5.34 vs. 5.22 mmol/L, p=0.03) despite similarities in obesity and total sugar and calorie availability. These results suggest that countries with higher availability of HFCS have a higher prevalence of type 2 diabetes independent of obesity.”
“Energy and Fructose from Beverages Sweetened with Sugar or High-Fructose Corn Syrup Pose a Health Risk for Some People” Bray, George A. Advances in Nutrition, 2013. DOI: 10.3945/an.112.002816. Abstract: “Sugar intake in the United States has increased by >40 fold since the American Revolution. The health concerns that have been raised about the amounts of sugar that are in the current diet, primarily as beverages, are the subject of this review. Just less than 50 percent of the added sugars (sugar and high-fructose corn syrup) are found in soft drinks and fruit drinks. […] Calorically sweetened beverages contribute to obesity through their caloric load, and the intake of beverages does not produce a corresponding reduction in the intake of other food, suggesting that beverage calories are ‘add-on’ calories. The increase in plasma triglyceride concentrations by sugar-sweetened beverages can be attributed to fructose rather than glucose in sugar. Several randomized trials of sugar-containing soft drinks versus low-calorie or calorie-free beverages show that either sugar, 50 percent of which is fructose, or fructose alone increases triglycerides, body weight, visceral adipose tissue, muscle fat, and liver fat. Fructose is metabolized primarily in the liver. […] By worsening blood lipids, contributing to obesity, diabetes, fatty liver, and gout, fructose in the amounts currently consumed is hazardous to the health of some people.”
“Impact of Perinatal Exposure to Sucrose or High-Fructose Corn Syrup (HFCS-55) on Adiposity and Hepatic Lipid Composition in Rat Offspring” Toop, Carla R.; et al. The Journal of Physiology, 2017. DOI: 10.1113/JP274066. Abstract: “Perinatal exposure to excess maternal intake of added sugars, including fructose and sucrose, is associated with an increased risk of obesity and type 2 diabetes in adult life. However, it is unknown to what extent the type of sugar and the timing of exposure affect these outcomes. The aim of this study was to determine the impact of exposure to maternal consumption of a 10 percent w/v [weight of solution in the total volume] beverage containing sucrose or high fructose corn syrup-55 (HFCS-55) during the prenatal and/or suckling periods on offspring at 3 and 12 weeks, utilizing a cross-fostering approach in a rodent model. […] This study suggests that the type of sugar and the timing of exposure (prenatal or suckling periods) are both important for determining the impact on metabolic health outcomes in the offspring.”
“Differential Effects of Fructose Versus Glucose on Brain and Appetitive Responses to Food Cues and Decisions for Food Rewards” Luo, Shan; et al. Proceedings of the National Academy of Sciences, 2015. DOI: 10.1073/pnas.1503358112. Abstract: “Fructose compared with glucose may be a weaker suppressor of appetite. Here we sought to determine the effects of fructose versus glucose on brain, hormone, and appetitive responses to food cues and food-approach behavior. We show that the ingestion of fructose compared with glucose resulted in smaller increases in plasma insulin levels and greater brain responses to food cues in the visual cortex and left orbital frontal cortex. Ingestion of fructose versus glucose also led to greater hunger and desire for food and a greater willingness to give up long-term monetary rewards to obtain immediate high-calorie foods. These findings suggest that ingestion of fructose relative to glucose activates brain regions involved in attention and reward processing and may promote feeding behavior.”
Academic papers that cast doubt on the alleged dangers: