High-fructose corn syrup (HFCS), also known as glucose-fructose, isoglucose and glucose-fructose syrup, is a sweetener made from corn starch. As in the production of conventional corn syrup, the starch is broken down into glucose by enzymes. To make HFCS, the corn syrup is further processed by glucose isomerase to convert some of its glucose into fructose. HFCS was first marketed in the early 1970s by the Clinton Corn Processing Company, together with the Japanese Agency of Industrial Science and Technology where the enzyme was discovered in 1965.:5
As a sweetener, HFCS is often compared to granulated sugar, but manufacturing advantages of HFCS over sugar include that it is easier to handle and more cost-effective. "HFCS 42" refers to 42% and "HFCS 55" to 55% fructose composition in manufacturing, respectively. HFCS 42 is mainly used for processed foods and breakfast cereals, whereas HFCS 55 is used mostly for production of soft drinks.
The United States Food and Drug Administration states that HFCS is a safe ingredient for food and beverage manufacturing. Uses and exports of HFCS from American producers have grown steadily during the early 21st century.
In the U.S., HFCS is among the sweeteners that mostly replaced sucrose (table sugar) in the food industry. Factors in the rise of HFCS use include production quotas of domestic sugar, import tariffs on foreign sugar, and subsidies of U.S. corn, raising the price of sucrose and lowering that of HFCS, making it cheapest for many sweetener applications. The relative sweetness of HFCS 55, used most commonly in soft drinks, is comparable to sucrose. HFCS (and/or standard corn syrup) is the primary ingredient in most brands of commercial "pancake syrup", as a less expensive substitute for maple syrup.
Because of its similar sugar profile and lower price, HFCS has been used illegally to "stretch" honey. Assays to detect adulteration with HFCS use differential scanning calorimetry and other advanced testing methods.
In the contemporary process, corn is milled to extract corn starch and an "acid-enzyme" process is used, in which the corn-starch solution is acidified to begin breaking up the existing carbohydrates. It is necessary to carry out the extraction process in the presence of mercuric chloride (0.01 M) in order to inhibit endogenous starch-degrading enzymes.:374-376 High-temperature enzymes are added to further metabolize the starch and convert the resulting sugars to fructose.:808-813 The first enzyme added is alpha-amylase, which breaks the long chains down into shorter sugar chains - oligosaccharides. Glucoamylase is mixed in and converts them to glucose; the resulting solution is filtered to remove protein, then using activated carbon, and then demineralized using ion-exchange resins. The purified solution is then run over immobilized xylose isomerase, which turns the sugars to ~50-52% glucose with some unconverted oligosaccharides and 42% fructose (HFCS 42), and again demineralized and again purified using activated carbon. Some is processed into HFCS 90 by liquid chromatography, and then mixed with HFCS 42 to form HFCS 55. The enzymes used in the process are made by microbial fermentation.:808-813:20-22
The most common forms of HFCS used for food and beverage manufacturing contain fructose in either 42% ("HFCS 42") or 55% ("HFCS 55") amounts, as described in the US Code of Federal Regulations (21 CFR 184.1866).
Commercial production of corn syrup began in 1964.:17 In the late 1950s, scientists at Clinton Corn Processing Company of Clinton, Iowa, tried to turn glucose from corn starch into fructose, but the process was not scalable.:17 In 1965-1970 Yoshiyuki Takasaki, at the Japanese National Institute of Advanced Industrial Science and Technology (AIST) developed a heat-stable xylose isomerase enzyme from yeast. In 1967, the Clinton Corn Processing Company obtained an exclusive license to a manufacture glucose isomerase derived from Streptomyces bacteria and began shipping an early version of HFCS in February 1967.:140 In 1983, the FDA approved HFCS as Generally Recognized as Safe (GRAS), and that decision was reaffirmed in 1996
Prior to the development of the worldwide sugar industry, dietary fructose was limited to only a few items. Milk, meats, and most vegetables, the staples of many early diets, have no fructose, and only 5-10% fructose by weight is found in fruits such as grapes, apples, and blueberries. Most traditional dried fruits, however, contain about 50% fructose. From 1970 to 2000, there was a 25% increase in "added sugars" in the U.S. After being classified as generally recognized as safe (GRAS) by the U.S. Food and Drug Administration in 1976, HFCS began to replace sucrose as the main sweetener of soft drinks in the United States. At the same time, rates of obesity rose. That correlation, in combination with laboratory research and epidemiological studies that suggested a link between consuming large amounts of fructose and changes to various proxy health measures, including elevated blood triglycerides, size and type of low-density lipoproteins, uric acid levels, and weight, raised concerns about health effects of HFCS itself.
Since 1789, the U.S. sugar industry has had trade protection against tariffs imposed by foreign-produced sugar, while subsidies to corn growers cheapen the primary ingredient in HFCS, corn. Industrial users looking for cheaper replacements rapidly adopted HFCS in the 1970s.
Production of HFCS in the United States was 8.3 million tons in 2017. HFCS is easier to handle than granulated sucrose, although some sucrose is transported as solution. Unlike sucrose, HFCS cannot be hydrolyzed, but the free fructose in HFCS may produce hydroxymethylfurfural when stored at high temperatures; these differences are most prominent in acidic beverages. Soft drink makers such as Coca-Cola and Pepsi continue to use sugar in other nations but transitioned to HFCS for U.S. markets in 1980 before completely switching over in 1984. Large corporations, such as Archer Daniels Midland, lobby for the continuation of government corn subsidies.
Consumption of HFCS in the U.S. has declined since it peaked at 37.5 lb (17.0 kg) per person in 1999. The average American consumed approximately 27.1 lb (12.3 kg) of HFCS in 2012, versus 39.0 lb (17.7 kg) of refined cane and beet sugar. This decrease in domestic consumption of HFCS resulted in a push in exporting of the product. In 2014, exports of HFCS were valued at $436 million, a decrease of 21% in one year, with Mexico receiving about 75% of the export volume.
In the European Union (EU), HFCS, known as isoglucose in sugar regime, is subject to a production quota. In 2005, this quota was set at 303,000 tonnes; in comparison, the EU produced an average of 18.6 million tonnes of sugar annually between 1999 and 2001.
In Japan, HFCS is manufactured mostly from imported U.S. corn, and the output is regulated by the government. For the period from 2007 to 2012, HFCS had a 27-30% share of the Japanese sweetener market.
Health concerns have been raised about a relationship between HFCS and metabolic disorders, and with regard to manufacturing contaminants. In general, however, the United States Food and Drug Administration has declared HFCS as a safe ingredient in food manufacturing, and there is no evidence that retail HFCS products contain harmful compounds or cause diseases.
HFCS is composed of 76% carbohydrates and 24% water, containing no fat, no protein, and no essential nutrients in significant amounts (table). In a 100 gram serving, it supplies 281 kilocalories, while in one tablespoon of 19 grams, it supplies 53 calories (table link).
In the 1980s and 1990s some publications cautioned consumption of sucrose and of HFCS.:18 In subsequent interviews, two of the study's authors stated the article was distorted to place emphasis solely on HFCS when the actual issue was the overconsumption of any type of sugar. While fructose absorption and modification by the intestines and liver does differ from glucose initially, the majority of the fructose molecules are converted to glucose or metabolized into byproducts identical to those produced by glucose metabolism. Consumption of moderate amounts of fructose has also been linked to positive outcomes, including reducing appetite if consumed before a meal, lower blood sugar increases compared to glucose, and (again compared to glucose) delaying exhaustion if consumed during exercise.
In 2007, an expert panel assembled by the University of Maryland's Center for Food, Nutrition and Agriculture Policy reviewed the links between HFCS and obesity and concluded there was no ecological validity in the association between rising body mass indexes (a measure of obesity) and the consumption of HFCS. The panel stated that since the ratio of fructose to glucose had not changed substantially in the United States since the 1960s when HFCS was introduced, the changes in obesity rates were probably not due to HFCS specifically, but rather a greater consumption of calories overall. In 2009, the American Medical Association published a review article on HFCS and concluded it was unlikely that HFCS contributed more to obesity or other health conditions than sucrose, and there was insufficient evidence to suggest warning about or restricting use of HFCS or other fructose-containing sweeteners in foods. The review did report that while some studies found direct associations between high intakes of fructose and other sugars and adverse health outcomes, including obesity and the metabolic syndrome, there was insufficient evidence to ban or restrict use of HFCS in the food supply or to require warning labels on products containing HFCS.
Epidemiological research has suggested that the increase in metabolic disorders such as obesity and non-alcoholic fatty liver disease is linked to increased consumption of sugars and/or calories in general and not due to any special effect of HFCS. A 2014 systematic review found little evidence for an association between HFCS consumption and liver diseases, enzyme levels or fat content. A 2012 review found that fructose did not appear to cause weight gain when it replaced other carbohydrates in diets with similar calories. One study investigating HFCS as a possible contributor to diabetes and obesity states that, "As many of the metabolic consequences of a diet high in fructose-containing sugars in humans can also be observed with high-fat or high-glucose feeding, it is possible that excess calories may be the main culprit in the development of the metabolic syndrome." Another study compared similar intakes of honey, white cane sugar, and HFCS, showing similar rises in both blood sugar level and triglycerides. High fructose consumption has been linked to high levels of uric acid in the blood, though this is only thought to be a concern for patients with gout.
Numerous agencies in the United States recommend reducing the consumption of all sugars, including HFCS, without singling it out as presenting extra concerns. The Mayo Clinic cites the American Heart Association's recommendation that women limit the added sugar in their diet to 100 calories a day (~6 teaspoons) and that men limit it to 150 calories a day (~9 teaspoons), noting that there is not enough evidence to support HFCS having more adverse health effects than excess consumption of any other type of sugar. The United States departments of Agriculture and Health and Human Services recommendations for a healthy diet state that consumption of all types of added sugars be reduced.:p.27
Since 2014, the United States Food and Drug Administration (FDA) has declared HFCS to be safe as a food ingredient. In 2015, production of HFCS in the United States was 8.5 million tons from some 500 million bushels of corn.
One consumer concern about HFCS is that processing of corn is more complex than used for "simpler" or "more natural" sugars, such as fruit juice concentrates or agave nectar, but all sweetener products derived from raw materials involve similar processing steps of pulping, hydrolysis, enzyme treatment, and filtration, among other common steps of sweetener manufacturing from natural sources. In the contemporary process to make HFCS, an "acid-enzyme" step is used in which the cornstarch solution is acidified to digest the existing carbohydrates, then enzymes are added to further metabolize the cornstarch and convert the resulting sugars to their constituents of fructose and glucose. Analyses published in 2014 showed that HFCS content of fructose was consistent across samples from 80 randomly selected carbonated beverages sweetened with HFCS.
One prior concern in manufacturing was whether HFCS contains reactive carbonyl compounds or advanced glycation end-products evolved during processing. This concern was dismissed, however, with evidence that HFCS poses no dietary risk from these compounds.
Through the early 21st Century, some factories manufacturing HFCS had used a chlor-alkali corn processing method which, in cases of applying mercury cell technology for digesting corn raw material, left trace residues of mercury in some batches of HFCS. In a 2009 release, The Corn Refiners Association stated that all factories in the American industry for manufacturing HFCS had used mercury-free processing over several previous years, making the prior report outdated. As of 2018, the USDA, FDA and US Centers for Disease Control list HFCS as a safe food ingredient, and do not mention mercury as a safety concern in HFCS products.
Most countries, including Mexico, use sucrose, or table sugar, in soft drinks. In the U.S., soft drinks, including Coca-Cola, are typically made with HFCS. Some Americans seek out drinks such as Mexican Coca-Cola in ethnic groceries because they prefer the taste over that of HFCS-sweetened Coca-Cola.Kosher Coca-Cola, sold in the U.S. around the Jewish holiday of Passover, also uses sucrose rather than HFCS and is highly sought after by people who prefer the original taste. While these are simply opinions, a 2011 study further backed up the idea that people enjoy sucrose (table sugar) more than HFCS. The study, conducted by Michigan State University, included a 99-member panel that evaluated yogurt sweetened with sucrose (table sugar), HFCS, and different varieties of honey for likeness. The results showed that, overall, the panel enjoyed the yogurt with sucrose (table sugar) added more than those that contained HFCS or honey.
In apiculture in the United States, HFCS is a honey substitute for some managed honey bee colonies during times when nectar is in low supply. However, when HFCS is heated to about 45 °C (113 °F), hydroxymethylfurfural, which is toxic to bees, can form from the breakdown of fructose. Although some researchers cite honey substitution with HFCS as one factor among many for colony collapse disorder, there is no evidence that HFCS is the only cause. Compared to hive honey, both HFCS and sucrose caused signs of malnutrition in bees fed with them, apparent in the expression of genes involved in protein metabolism and other processes affecting bee health.
There are various public relations concerns with HFCS, including how HFCS products are advertised and labeled as "natural". As a consequence, several companies reverted to manufacturing with sucrose (table sugar) from products that had previously been made with HFCS. In 2010, the Corn Refiners Association (CRA) applied to allow HFCS to be renamed "corn sugar", but that petition was rejected by the United States Food and Drug Administration in 2012.
In August 2016 in a move to please consumers with health concerns, McDonald's announced they would be replacing all HFCS in their buns with sucrose (table sugar) and would cut out preservatives and other artificial additives from their menu items. Marion Gross, senior vice president of McDonald's stated, "We know that they [consumers] don't feel good about high-fructose corn syrup so we're giving them what they're looking for instead." Over the early 21st century, other companies such as Yoplait, Gatorade, and Hershey's also phased out HFCS, replacing it with conventional sugar because consumers perceived sugar to be healthier. Companies such as PepsiCo and Heinz have also released products that use sugar in lieu of HFCS, although they still sell HFCS-sweetened products.
Because the sugar profile of high-fructose corn syrup is similar to that of honey, high-fructose corn syrup was more difficult to detect until new tests were developed in the 1980s. Honey adulteration has continued to evolve to evade testing methodology, requiring continual updating of testing methods.
At this time, there's insufficient evidence to say that high-fructose corn syrup is any less healthy than other types of sweeteners.