Vol.3, # 23
June 17, 2006

Q: What is fructose corn syup and high fructose corn syrup and are they safe to use? - Layperson

A: Corn syrup, known as glucose syrup outside Canada and the United States, is a syrup made from corn starch and composed mainly of glucose. A series of three enzymatic reactions is used to convert the corn starch to corn syrup. It is used to sweeten commercially prepared foods. Its moisture retaining (humectant) properties keep foods moist and maintain freshness.

Like ordinary corn syrup, the high fructose variety is made from corn starch using enzymes. The production process of HFCS was developed by Japanese researchers in the 1970s. HFCS was rapidly introduced in many processed foods and soda drinks in the US over the period of about 1975 - 1985, and usage continues to increase as sugar use decreases at a nearly one to one level (Bray, 2004 & U.S. Department of Agriculture, Economic Research Service, Sugar and Sweetener Yearbook series, Tables 50 - 52.).

By increasing fructose content of corn syrup (glucose), the syrup is more comparable to table sugar (sucrose). This makes it useful to manufacturers as a possible substitute for sugar in soft drinks and other processed foods. Unlike sucrose, HFCS consists of a mixture of glucose and fructose, which doesn't require an enzymatic step to break it down before absorption in the intestine.

Through enzymatic processing, the fructose content of corn syrup can be increased to yield a product with similar properties to table sugar. Common commercial grades of high fructose corn syrup include fructose contents of 42%, 55%, or 90%. The 55% grade is most commonly used in soft drinks and equivalent to caster sugar.Comparison to other sugars

Sucrose (table sugar) is a disaccharide composed of one unit each of fructose and glucose linked together. Sucrose is 50% fructose, so HFCS may have a higher or lower fructose content than sucrose, with a corresponding change in sweetness. Sucrose is broken down during digestion into fructose and glucose through hydrolysis by the enzyme sucrase.

Honey is another product that is a mixture of different types of sugars, water, and small amounts of other compounds. Honey typically has a fructose/glucose ratio similar to HFCS, as well as containing some sucrose and other sugars.

Contrary to its name, HFCS is not high in fructose. At the time HFCS was developed, the only sweetener in all other corn syrups was glucose; none contained fructose. So the name "high" fructose corn syrup, in comparative terms, makes sense and is entirely appropriate. But when compared to table sugar (sucrose), HFCS is not at all "high" in fructose. In fact, HFCS is nearly identical in composition to table sugar (sucrose), which is composed of 50 percent fructose and 50 percent glucose.  HFCS is composed of either 42 percent or 55 percent fructose, with the remaining sugars being primarily glucose and some higher sugars. HFCS is used in foods and beverages because of the many benefits it offers. In addition to providing sweetness at a level equivalent to table sugar (1), HFCS makes foods such as bread and breakfast cereal "brown" better when baked, and gives chewy cookies and snack bars their soft texture. It also protects freshness. HFCS actually inhibits microbial spoilage by reducing water activity and extends shelf life through superior moisture control.Both HFCS products share functional advantages, but each offers special qualities to food manufacturers and consumers. The sweeter HFCS-55 has a predominant role in carbonated colas and soft drinks. HFCS-42 is popular in canned fruits, condiments, baked goods and other processed foods for its mild sweetness that won't mask natural flavors. The dairy industry uses HFCS-42 in fluid products such as flavored milks and eggnog; yogurt, ice cream and other frozen desserts and novelties. 

Is HFCS sweeter than sugar?

No. When HFCS was developed it was specifically formulated to provide sweetness equivalent to sucrose (table sugar). In order for food and beverage makers to use HFCS in place of sucrose, it was important that it provide the same level of sweetness as sucrose so that consumers would not perceive a difference in product sweetness and taste. HFCS is marketed in two formulations, HFCS-55 and HFCS-42 (55 and 42 represent the percentage of fructose.) HFCS-55 has sweetness equivalent to sucrose and is used in many carbonated soft drinks in the United States. HFCS-42 is somewhat less sweet and is used in many fruit-flavored noncarbonated beverages, baked goods and other products in which its special characteristics such as fermentability, lower freezing point, surface browning or flavor enhancement add value to the product.

With regards to fruit, the ratio is usually 50 percent glucose and 50 percent fructose, but most commercial fruit juices have HFCS added. Fruit contains fiber which slows down the metabolism of fructose and other sugars, but the fructose in HFCS is absorbed very quickly.

For many years, Dr. Meira Fields and her coworkers at the US Department of Agriculture investigated the harmful effects of dietary sugar on rats. They discovered that when male rats are fed a diet deficient in copper, with sucrose as the carbohydrate, they develop severe pathologies of vital organs. Liver, heart and testes exhibit extreme swelling, while the pancreas atrophies, invariably leading to death of the rats before maturity.

Sucrose is a disaccharide composed of 50 percent glucose and 50 percent fructose. Dr. Fields repeated her experiments to determine whether it was the glucose or fructose moiety that caused the harmful effects. Starch breaks down into glucose when digested. On a copper-deficient diet, the male rats showed some signs of copper deficiency, but not the gross abnormalities of vital organs that occur in rats on the sucrose diet. When the rats were fed fructose, the fatal organ abnormalities occured.

Lysl oxidase is a copper-dependent enzyme that participates in the formation of collagen and elastin. Fructose seems to interfere with copper metabolism to such an extent that collagen and elastin cannot form in growing animals—hence the hypertrophy of the heart and liver in young males. The females did not develop these abnormalities, but they resorbed their litters.

These experiements should give us pause when we consider the great increase in the use of high fructose corn syrup during the past 30 years, particularly in soft drinks, fruit juices and other beverages aimed at growing children, children increasingly likely to be copper deficient as modern parents no longer serve liver to their families. (Liver is by far the best source of copper in human diets.)

"The bodies of the children  today are mush," observed a concerned chiropractor recently. The culprit is the modern diet, high in fructose and low in copper-containing foods, resulting in inadequate formation of elastin and collagen—the sinews that hold the body together.


Until the 1970s most of the sugar we ate came from sucrose derived from sugar beets or sugar cane.  Then sugar from corn—corn syrup, fructose, dextrose, dextrine and especially high fructose corn syrup (HFCS)—began to gain popularity as a sweetener because it was much less expensive to produce. High fructose corn syrup can be manipulated to contain equal amounts of fructose and glucose, or up to 80 percent fructose and 20 percent glucose. Thus, with almost twice the fructose, HFCS delivers a double danger compared to sugar.

In 1980 the average person ate 39 pounds of fructose and 84 pounds of sucrose. In 1994 the average person ate 66 pounds of sucrose and 83 pounds of fructose, providing 19 percent of total caloric energy. Today approximately 25 percent of our average caloric intake comes from sugars, with the larger fraction as fructose.

High fructose corn syrup is extremely soluble and mixes well in many foods. It is cheap to produce, sweet and easy to store. It's used in everything from bread to pasta sauces to bacon to beer as well as in "health products" like protein bars and "natural" sodas.


In the past, fructose was considered beneficial to diabetics because it is absorbed only 40 percent as quickly as glucose and causes only a modest rise in blood sugar. However, research on other hormonal factors suggests that fructose actually promotes disease more readily than glucose. Glucose is metabolized in every cell in the body but all fructose must be metabolized in the liver. The livers of test animals fed large amounts of fructose develop fatty deposits and cirrhosis, similar to problems that develop in the livers of alcoholics.

Pure fructose contains no enzymes, vitamins or minerals and robs the body of its micronutrient treasures in order to assimilate itself for physiological use. While naturally occurring sugars, as well as sucrose, contain fructose bound to other sugars, high fructose corn syrup contains a good deal of "free" or unbound fructose.  Research indicates that this free fructose interferes with the heart's use of key minerals like magnesium, copper and chromium. Among other consequences, HFCS has been implicated in elevated blood cholesterol levels and the creation of blood clots.  It has been found to inhibit the action of white blood cells so that they are unable to defend the body against harmful foreign invaders.

Studies on the Maillard reaction indicate that fructose may contribute to diabetic complications more readily than glucose. The Maillard reaction is a browning reaction that occurs when compounds are exposed to various sugars. Fructose browns food seven times faster than glucose, resulting in a decrease in protein quality and a toxicity of protein in the body. This is due to the loss of amino acid residues and decreased protein digestibility. Maillard products can inhibit the uptake and metabolism of free amino acids and other nutrients such as zinc, and some advanced Maillard products have mutagenic and/or carcinogenic properties. The Maillard reactions between proteins and fructose, glucose, and other sugars may play a role in aging and in some clinical complications of diabetes.

Fructose reduces the affinity of insulin for its receptor, which is the hallmark of type-2 diabetes. This is the first step for glucose to enter a cell and be metabolized. As a result, the body needs to pump out more insulin to handle the same amount of glucose.


Nancy Appleton, PhD, clinical nutritionist, has compiled a list of the harmful effects of fructose in her books Lick the Sugar Habit, Healthy Bones, Heal Yourself With Natural Foods, The Curse Of Louis Pasteur and Lick the Sugar Habit Sugar Counter. She points out that consumption of fructose causes a significant increase in the concentration of uric acid; after ingestion of glucose, no significant change occurs. An increase in uric acid can be an indicator of heart disease. Furthermore, fructose ingestion in humans results in increases in blood lactic acid, especially in patients with preexisting acidotic conditions such as diabetes, postoperative stress or uremia. Extreme elevations cause metabolic acidosis and can result in death.

Fructose is absorbed primarily in the jejunum before metabolism in the liver. Fructose is converted to fatty acids by the liver at a greater rate than is glucose. When consumed in excess of dietary glucose, the liver cannot convert all of the excess fructose in the system and it may be malabsorbed. The portion that escapes conversion may be thrown out in the urine. Diarrhea can be a consequence. A study of 25 patients with functional bowel disease showed that pronounced gastrointestinal distress may be provoked by malabsorption of small amounts of fructose.

Fructose interacts with oral contraceptives and elevates insulin levels in women on "the pill."

In studies with rats, fructose consistently produces higher kidney calcium concentrations than glucose. Fructose generally induces greater urinary concentrations of phosphorus and magnesium and lowered urinary pH compared with glucose.

In humans, fructose feeding leads to mineral losses, especially higher fecal excretions of iron and magnesium, than did subjects fed sucrose. Iron, magnesium, calcium, and zinc balances tended to be more negative during the fructose-feeding period as compared to balances during the sucrose-feeding period.

There is significant evidence that high sucrose diets may alter intracellular metabolism, which in turn facilitates accelerated aging through oxidative damage. Scientists found that the rats given fructose had more undesirable cross-linking changes in the collagen of their skin than in the other groups. These changes are also thought to be markers for aging. The scientists say that it is the fructose molecule in the sucrose, not the glucose, that plays the larger part.

Because it is metabolized by the liver, fructose does not cause the pancreas to release insulin the way it normally does. Fructose converts to fat more than any other sugar. This may be one of the reasons Americans continue to get fatter. Fructose raises serum triglycerides significantly. As a left-handed sugar, fructose digestion is very low. For complete internal conversion of fructose into glucose and acetates, it must rob ATP energy stores from the liver.

Not only does fructose have more damaging effects in the presence of copper deficiency, fructose also inhibits copper metabolism—another example of the sweeteners double-whammy effect. A deficiency in copper leads to bone fragility, anemia, defects of the connective tissue, arteries, and bone, infertility, heart arrhythmias, high cholesterol levels, heart attacks, and an inability to control blood sugar levels.

Although these studies were not designed to test the effects of fructose on weight gain, the observation of increased body weight associated with fructose ingestion is of interest. One explanation for this observation could be that fructose ingestion did not increase the production of two hormones, insulin and leptin, that have key roles in the long-term regulation of food intake and energy expenditure.


The magnitude of the deleterious effects of fructose varies depending on such factors as age, sex, baseline glucose, insulin, triglyceride concentrations, the presence of insulin resistance, and the amount of dietary fructose consumed. Some people are more sensitive to fructose. They include hypertensive, hyperinsulinemic, hypertriglyceridemic, non-insulin dependent diabetic people, people with functional bowel disease and postmenopausal women.

Everyone should avoid over-exposure to fructose, but especially those listed above. One or two pieces of fruit per day is fine, but commercial fruit juices and any products containing high fructose corn syrup aremore dangerous than sugar and should be removed from the diet.

Sweetener consumption patterns

In the United States

US sweetener consumption, 1966-2004 (cane and beet sugar are both pure sucrose)
US sweetener consumption, 1966-2004 (cane and beet sugar are both pure sucrose)

The accompanying graph shows the consumption of sweeteners per capita in the United States since 1966. Since HFCS and sucrose (cane and beet sugars) provide almost identical proportions of fructose and glucose, no metabolic changes would be expected from substituting one for the other. However, it is apparent from this graph that overall sweetener consumption, and in particular glucose-fructose mixtures, has increased since the introduction of HFCS. Thus, the proportion of fructose as a component of overall sweetener intake in the United States has increased since the early 1980s. This would be true whether the added sweetener was HFCS, table sugar, or any other glucose-fructose mixture.

International markets

Currently, HFCS remains an almost uniquely American phenomenon.

In Europe, whilst HFCS is not specifically banned, the greater availability of cane sugar over maize would make it uneconomical to produce it there.

The average American consumed approximately 42.3 lb of HFCS versus 44.0 lb of sugar in 2004. By contrast, where HFCS is not used or rarely used (EU, Brazil, Australia), the sugar consumption per person is nearly double or more than the USA.

One study concluded that Fructose "produced significantly higher fasting plasma triacylglycerol values than did the glucose diet in men". The research, led by J.P Bantle, concluded that "if plasma triacylglycerols are a risk factor for cardiovascular disease, then diets high in fructose may be undesirable" (Bantle, 2000). However, this study looked at the effects of fructose independently. As noted by the U.S. Food and Drug Administration in 1996, the saccharide composition (glucose to fructose ratio) of HFCS is approximately the same as that of honey, invert sugar and the disaccharide sucrose (or table sugar).

A more recent study by Dr. George Bray (2004) found a link exists between obesity and high HFCS consumption (Bray, 2004), especially from soft drinks. On the other hand, University of California, Davis nutrition researcher Peter Havel, PhD, point out that while there are likely differences between sweeteners, "the increased consumption of fat, the increased consumption of all sugars, and inactivity are all to blame for the obesity epidemic." 

  • Bantle, et al, "Effects of dietary fructose on plasma lipids in healthy subjects", American Journal of Clinical Nutrition, Vol. 72, No. 5, 1128-1134, November 2000
  • Bray, George A, "Consumption of high-fructose corn syrup in beverages may play a role in the epidemic of obesity" American Journal of Clinical Nutrition, Vol. 79, No. 4, 537-543, April 2004

Labeling restrictions

In May 2006, the Center for Science in the Public Interest (CSPI) threatened[1] to file a lawsuit against Cadbury Schweppes for labeling 7UP as "All Natural" despite containing high fructose corn syrup. While the FDA has no definition of "Natural", CSPI claims that HFCS is not a “natural” ingredient due to the high level of processing required to produce it.


High-fructose corn syrup (HFCS) is produced by processing corn starch to yield glucose, and then processing the glucose to produce a syrup with a higher percentage of fructose.

First, cornstarch is treated with alpha-amylase to produce shorter chains of sugars called polysaccharides.

Next, an enzyme called glucoamylase breaks the sugar chains down even further to yield the simple sugar glucose.

The third enzyme, glucose-isomerase, converts glucose to a mixture of about 42% fructose and 50–52% glucose with some other sugars mixed in. While alpha-amylase and glucoamylase are added directly to the slurry, glucose-isomerase is packed into columns and the sugar mixture is then passed over it. This 42–43% fructose glucose mixture is then subjected to a liquid chromatography step where the fructose is enriched to approximately 90%. The 90% fructose is then back-blended with 42% fructose to achieve a 55% fructose final product. Numerous ion-exchange and evaporation steps are also part of the overall process.

In short, fructose corn syrup and high fructose corn syrup are relatively safe to use in limited amounts. Those with corn allergies, cholesterol, lipid, triglyceride, pregnant/lactating, and blood sugar abnormalities, should consult an healthcare professional.


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