High-fructose corn syrup: is it worse than sugar?
High-fructose corn syrup (HFCS) is a liquid sweetener made from corn (maize) starch, used widely in American processed food and soft drinks. Its fearsome reputation is mostly undeserved: once it reaches your gut it is almost chemically identical to ordinary table sugar, and at the same dose the evidence does not show it to be meaningfully worse. The real issue is the total amount of added sugar, and the fructose within it, rather than this one syrup. In the UK you are unlikely to be eating much of it anyway.
Key facts
- HFCS comes in two main grades: HFCS-42 (about 42 percent fructose) and HFCS-55 (about 55 percent fructose). Table sugar (sucrose) is 50 percent fructose and 50 percent glucose.1
- Because HFCS-55 and sucrose deliver nearly the same fructose-to-glucose mix, most of the harms blamed on HFCS actually track total added sugar, not HFCS specifically.1
- In the UK and EU it is called glucose-fructose syrup, fructose-glucose syrup or isoglucose, and it is far less common than in the US.2
- A 2022 meta-analysis of randomised trials (767 participants) found no significant difference between HFCS and sucrose for weight, blood lipids, blood glucose or inflammation.9
- UK adults already eat roughly two to three times the recommended limit for free sugars, whatever the source.34
What HFCS actually is
HFCS is made by breaking corn starch down into glucose, then using an enzyme (glucose isomerase) to convert some of that glucose into fructose, which tastes sweeter. The result is a cheap, pourable syrup that manufacturers like for its consistency and shelf life. They blend it to a target fructose content, which is why you see numbered grades.1
Two grades dominate. HFCS-55 is about 55 percent fructose and 42 percent glucose, and is the version used in American soft drinks. HFCS-42 is about 42 percent fructose and 53 percent glucose, used in baked goods, breakfast cereals, tinned products and many processed foods. The small remainder in each is other corn sugars.1 Despite the name, neither is overwhelmingly fructose: the word "high" simply means higher than the plain glucose syrup it is made from, not high in absolute terms.
Why you rarely see it in the UK
If you read British and American labels side by side, you will notice HFCS almost everywhere in the US and almost nowhere in the UK. This is history and economics, not a safety ban. The US grows vast amounts of subsidised corn, which made corn syrup cheaper than sugar from the 1970s onwards. Europe, by contrast, grew sugar beet and protected it.
For nearly fifty years the EU capped production of "isoglucose" (its regulatory word for these syrups) at a small share of the sweetener market, and that cap only ended on 30 September 2017.2 Cheap home-grown beet sugar was already entrenched, so uptake has stayed low even since. On a UK or EU label the same family of syrups appears under different names depending on which sugar dominates: glucose-fructose syrup when there is more glucose, and fructose-glucose syrup when there is more fructose.
| Term you may see | What it means |
|---|---|
| High-fructose corn syrup (HFCS) | US term; usually HFCS-42 or HFCS-55 |
| Glucose-fructose syrup | UK/EU label term when fructose is under 50 percent (equivalent to HFCS-42) |
| Fructose-glucose syrup | UK/EU label term when fructose is over 50 percent (equivalent to HFCS-55) |
| Isoglucose | The EU policy and trade name for the same family of syrups |
HFCS versus table sugar: the biochemistry
This is the heart of the matter, and it is more reassuring than the headlines suggest. Table sugar, sucrose, is a single molecule made of one glucose unit and one fructose unit chemically bonded together. HFCS is a mixture of those same two sugars, but free and unbonded. The only real difference is that bond, and your gut splits sucrose into its two halves within minutes of eating it.1
So after digestion, a can of cola sweetened with HFCS-55 and a cup of tea sweetened with sucrose deliver almost the same thing to your bloodstream: roughly equal parts glucose and fructose. HFCS-55 carries only a few percent more fructose than sucrose, a difference too small to matter for health at normal intakes.1 This is the single most important fact in the whole debate, and it is why most researchers treat the two as broadly interchangeable.
| Sweetener | Fructose | Glucose | Form | Typical use |
|---|---|---|---|---|
| Table sugar (sucrose) | ~50 percent | ~50 percent | Bonded (one molecule) | UK default sweetener |
| HFCS-55 | ~55 percent | ~42 percent | Free, unbonded | US soft drinks |
| HFCS-42 | ~42 percent | ~53 percent | Free, unbonded | US baked goods, cereals, sauces |
| Plain glucose syrup | Very low | ~95 percent or more | Free | Confectionery; not a major fructose source |
The genuine metabolic concerns
The concerns that are real attach to fructose, and therefore to all added sugars that contain it, including ordinary table sugar, rather than to HFCS as a special villain. Fructose is handled differently from glucose. While almost every cell in the body can burn glucose, fructose is processed mainly in the liver, and in large, rapid doses (the kind you get from a sugary drink, not from a piece of fruit) this has several knock-on effects.
Liver fat and triglycerides
The liver can turn surplus fructose into fat, a process called de novo lipogenesis. In a 2021 randomised controlled trial, Bettina Geidl-Flueck and colleagues gave 94 healthy men a daily drink sweetened with fructose, glucose, sucrose or nothing for seven weeks. Drinks containing fructose or sucrose roughly doubled the liver's fat production, while the glucose drink did not, even though calorie intake was similar across groups.5 Over time this is one of the pathways to raised blood triglycerides and to fatty liver disease (MASLD).
Uric acid
Metabolising fructose burns cellular energy (ATP) quickly, and a by-product of that process is uric acid. Richard Johnson and colleagues have argued that this fructose-driven rise in uric acid may itself feed insulin resistance and high blood pressure.7 This is largely a mechanistic and hypothesis-driven case rather than settled fact, and whether uric acid is a true cause or simply a marker remains debated. It is, however, a plausible reason high-fructose intakes track with gout and metabolic problems. We cover it in detail in our uric acid and fructose guide.
Appetite signalling
Fructose does not raise insulin or the satiety hormone leptin the way glucose does, and it blunts the normal fall in the hunger hormone ghrelin after a meal. In a controlled study of 12 women, Karen Teff and colleagues found that fructose-sweetened meals produced lower insulin and leptin, and less ghrelin suppression, than glucose-sweetened ones.8 The concern is that liquid fructose calories may be less filling, making them easy to overconsume. This was a small, short, mechanistic study, so it is best treated as a clue rather than proof.
Evidence note: The cleanest experiments compare fructose against glucose, not HFCS against sugar. In a 10-week trial, Kimber Stanhope and colleagues had overweight and obese adults drink either fructose- or glucose-sweetened beverages at a quarter of their daily calories. Both groups gained similar weight, but only the fructose group added visceral (belly) fat, raised their triglycerides and became less insulin-sensitive.6 The lesson is that the fructose component carries most of the metabolic risk, which is exactly the part that HFCS and table sugar share almost equally.
Is HFCS uniquely worse than sugar?
On the best available evidence, no, not at the same dose. A 2022 systematic review and meta-analysis by Xiang Li, Yunqi Luan and colleagues pooled randomised trials that compared HFCS with sucrose directly (four studies, nine comparison arms, 767 people). It found no significant difference in body weight, blood lipids, blood glucose, calorie intake or markers of inflammation.9 When two sweeteners deliver almost the same sugars, that is the result you would expect.
What does matter is dose. A large meta-analysis of controlled feeding trials by John Sievenpiper and colleagues found that fructose did not cause weight gain when it simply replaced other carbohydrates at the same calorie level, but it did add weight when it was piled on top as extra calories.10 In other words, the problem is having too much added sugar in total, in a form that is easy to over-consume, rather than which syrup it came from.
Separating evidence from speculation: It is well established, from randomised trials, that fructose-containing sugars raise liver fat and triglycerides more than glucose, and that HFCS and sucrose behave alike at equal doses. It is plausible but not proven, resting on mechanistic and observational work, that fructose-driven uric acid and weaker appetite signals make sugary drinks especially fattening. The popular claim that HFCS is a uniquely toxic ingredient, distinct from sugar, is not supported by the trial evidence.
Where it hides in food
In the US, HFCS turns up in soft drinks, fruit-flavoured drinks, sweetened yoghurts, breakfast cereals, biscuits, tinned fruit, sauces, ketchup, salad dressings and even some breads. In the UK it is far rarer, but you may still meet it as glucose-fructose syrup or fructose-glucose syrup in some confectionery, soft drinks, jams, ice cream and sports or energy products, and in imported American foods.2
The practical point is that chasing the words "corn syrup" off your labels is the wrong target. Whether a product is sweetened with HFCS, glucose-fructose syrup, sucrose, cane sugar, honey or fruit-juice concentrate, your body sees much the same fructose and glucose. The number worth reading is the "of which sugars" line and, on UK packaging, the free-sugars content, not the specific name of the sweetener.3
The sensible bottom line
HFCS is not a special poison, and swapping a fizzy drink made with it for one made with cane sugar buys you essentially nothing. Both are concentrated added sugar, roughly half fructose, and both are easy to drink in quantities you would never sit down and eat as whole food. UK guidance is to keep free sugars to no more than about 5 percent of your daily energy, which works out at around 30 grams (about seven sugar cubes) a day for an adult, and most of us are comfortably over that.34
If you want one change that matters, it is cutting sugar-sweetened drinks of any kind, because they are the easiest way to take in a lot of liquid fructose quickly. That single step does more for your liver, triglycerides and waistline than worrying about which syrup is printed on the label. For a structured way to make changes one at a time, see our start here guide and the stack builder.
- Given my added-sugar and soft-drink intake, should we check my triglycerides and a full lipid panel?
- Do I have enough metabolic risk factors to be screened for fatty liver, for example with a FIB-4 score?
- I get gout or have high uric acid: could my intake of sugary drinks be contributing?
- Is my HbA1c or fasting glucose in a range I should be acting on now?
References
- White JS, 2008. Straight talk about high-fructose corn syrup: what it is and what it ain't. American Journal of Clinical Nutrition 88(6):1716S-1721S. link
- European Commission, 2017. EU sugar quota system comes to an end (press release IP/17/3487). link
- NHS. Sugar: the facts. link
- Scientific Advisory Committee on Nutrition (SACN), 2015. Carbohydrates and Health. London: TSO. link
- Geidl-Flueck B, Hochuli M, Nemeth A, et al., 2021. Fructose- and sucrose- but not glucose-sweetened beverages promote hepatic de novo lipogenesis: a randomized controlled trial. Journal of Hepatology 75(1):46-54. link
- Stanhope KL, Schwarz JM, Keim NL, et al., 2009. Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans. Journal of Clinical Investigation 119(5):1322-1334. link
- Johnson RJ, Nakagawa T, Sanchez-Lozada LG, et al., 2013. Sugar, uric acid, and the etiology of diabetes and obesity. Diabetes 62(10):3307-3315. link
- Teff KL, Elliott SS, Tschop M, et al., 2004. Dietary fructose reduces circulating insulin and leptin, attenuates postprandial suppression of ghrelin, and increases triglycerides in women. Journal of Clinical Endocrinology and Metabolism 89(6):2963-2972. link
- Li X, Luan Y, Li Y, et al., 2022. The effect of high-fructose corn syrup vs. sucrose on anthropometric and metabolic parameters: a systematic review and meta-analysis. Frontiers in Nutrition 9:1013310. link
- Sievenpiper JL, de Souza RJ, Mirrahimi A, et al., 2012. Effect of fructose on body weight in controlled feeding trials: a systematic review and meta-analysis. Annals of Internal Medicine 156(4):291-304. link
This article is educational and does not constitute medical advice, diagnosis, or a treatment recommendation. Medication uses described as “off-label” are not licensed for that purpose in the UK and should only be considered under qualified clinical supervision. Always speak to your GP, pharmacist, or a registered specialist before starting, stopping, or changing any treatment. If you have severe or alarm symptoms - unintentional weight loss, blood in your stool, difficulty swallowing, persistent vomiting, a fever, or severe pain - seek urgent medical care.