Table of Contents

What Is High Fructose Corn Syrup (HFCS / Isoglucose)?

Differences from Sugar, Effects on the Body, Global Perspective, and How to Handle It Wisely

Quick Takeaways: What You’ll Learn in This Article

You often see “glucose-fructose syrup” or “fructose-glucose syrup” on ingredient labels for soft drinks and snacks.
Even if you recognize the names, you may still feel uneasy and wonder:

Is it more dangerous than regular sugar?
Is it really responsible for obesity, diabetes, or fatty liver?
How much should I actually worry about it?

In this article, we’ll整理 (organize) the following points as clearly as possible:

What high fructose/glucose-fructose syrup (isoglucose) is, and how it’s defined under Japan’s JAS standards
How it relates to American High Fructose Corn Syrup (HFCS)
Its links with obesity, diabetes, fatty liver, cardiovascular disease, and more (including recent research)
Differences between sugar and HFCS, and why “how much you cut both of them” matters more than which one you choose
How Japan, the EU, the U.S., etc. classify and label these sweeteners
Realistic ways to include or avoid them in everyday life

This should be especially helpful for:

Households that regularly buy soft drinks and processed foods
People on a diet or pre-diabetic who are concerned about sugar intake
Parents wondering how to choose snacks and drinks for their children
People involved in product development, school meals, or restaurant menu design

I’ll explain things a bit more carefully than usual so it’s practical for all of you.

1. What Is Glucose-Fructose Syrup? Basics of Isoglucose and the JAS Definition

1-1. What is isoglucose?

“Glucose-fructose syrup” is one type of isoglucose.
Isoglucose is a liquid sweetener made mainly from starch—typically corn, potatoes, or sweet potatoes—through the following steps:

Starch is broken down into glucose using enzymes or acid
Part of that glucose is converted into fructose by an enzyme called glucose isomerase

The result is a liquid sugar whose main components are glucose and fructose.

Because it’s easy to handle as a liquid, resists crystallization, and tastes sweet even in cold drinks, it’s used in a very wide range of processed foods:

Soft drinks and sports drinks
Fermented milk drinks
Sauces and seasonings
Bread and baked goods
Sweets and snacks

1-2. How Japan’s JAS (Agricultural Standards) classify it

In Japan, isoglucose is defined under JAS according to its fructose content:

Fructose content less than 50%
→ Glucose-fructose syrup (ぶどう糖果糖液糖)
Fructose content 50%–less than 90%
→ Fructose-glucose syrup (果糖ぶどう糖液糖)
Fructose content 90% or more
→ High-fructose syrup (高果糖液糖)

The order of “glucose” and “fructose” in the name indicates which one is more abundant, which is the key point.

Furthermore, if 10% or more sugar (sucrose) is added to any of these, they are labelled as:

“Sugar-mixed glucose-fructose syrup”
“Sugar-mixed fructose-glucose syrup”

and so on.

1-3. Relationship to “HFCS” in the U.S.

The “high fructose corn syrup” (HFCS) that has drawn concern in the U.S. is, broadly speaking, corn-derived isoglucose.

Typical types include:

HFCS-42: Around 42% fructose (similar to Japanese glucose-fructose syrup)
HFCS-55: Around 55% fructose (roughly equivalent to Japanese fructose-glucose syrup)

HFCS-55 has been widely used, especially in colas and other soft drinks.

So when you see “果糖ぶどう糖液糖 (fructose-glucose syrup)” on a Japanese beverage label, it’s fair to think of it as close to HFCS-55 in the U.S.

2. Different Names and Labels Around the World, and What Foods It’s In

2-1. EU terminology: “glucose-fructose syrup”

In Europe, starch-based sugar syrups are labelled according to EU directives as follows:

Fructose less than 5% … Glucose syrup
Fructose 5–49.9% … Glucose-fructose syrup (glucose-dominant)
Fructose 50–95% … Fructose-glucose syrup (fructose-dominant)

In other words, when you see “glucose-fructose syrup” or “fructose-glucose syrup” on a European ingredient label, you can think of it as equivalent to what Japan calls “isoglucose” (glucose-fructose syrup / fructose-glucose syrup).

2-2. Common labels in Japan

On Japanese ingredient lists, you’ll see things like:

ぶどう糖果糖液糖 (glucose-fructose syrup)
果糖ぶどう糖液糖 (fructose-glucose syrup)
高果糖液糖 (high-fructose syrup)
砂糖混合ぶどう糖果糖液糖 (sugar-mixed glucose-fructose syrup), etc.

Soft drink labels often look like this:

Ingredients: fructose-glucose syrup (made in Japan), sugar, ◯◯ juice / acidulants, flavoring…

Quite often, these syrups appear first in the list.
Because ingredients are listed in order of quantity used, this can mean:

“The single largest component of this drink is fructose-glucose syrup.”

2-3. Foods and drinks where it’s especially common

Typical examples include:

Carbonated soft drinks, sports drinks, and fermented milk drinks
Flavored waters and vitamin drinks
Ready-to-drink coffee and tea beverages
Sweet breads, snacks, and breakfast cereals
Sauces, dressings, noodle dips, and other condiments
Pickles and prepared side dishes

Because it’s easy to handle as a liquid and relatively inexpensive, it’s widely used in “sweet, cheap, mass-produced” processed foods.

3. Why Is It Called “Bad for You”? Three Main Concerns

There are three broad reasons why glucose-fructose syrup (including HFCS) has been criticized:

It tastes sweet and goes down easily, leading to excess calorie intake
Excess fructose may negatively affect liver and fat metabolism
Compared with consuming the same calories from sugar, it may offer no meaningful benefit

Let’s walk through these.

3-1. Liquid sugars are easy to “overdrink”

Glucose-fructose syrup is used mainly in beverages and liquid foods.
Liquid sugars:

Are consumed quickly in large amounts, without chewing
Don’t give a strong feeling of fullness, so they don’t reduce overall food intake much

As a result, many studies have pointed out that “sugars consumed in drinks tend to promote weight gain”, whether they come from sugar or from HFCS.

The WHO also recommends that, regardless of sugar type, “free sugars” (added sugars plus sugars in fruit juices, etc.) be kept below 10% of daily energy intake—and ideally below 5%.

3-2. Fructose’s “straight to the liver” route and fatty liver

Glucose is distributed throughout the body and used as an energy source by many cells.
Fructose, on the other hand, is processed mainly in the liver.

Excessive fructose intake can:

Increase de novo lipogenesis (the liver’s synthesis of triglycerides)
Promote fat buildup in the liver (non-alcoholic fatty liver disease, NAFLD)
Raise triglycerides and uric acid, increasing risks of metabolic syndrome and gout

These mechanisms have been shown in animal experiments and human studies.

In particular, recent systematic reviews (from around 2023–2025) again report that long-term intake of sugar-sweetened beverages high in HFCS increases liver fat and inflammation.

3-3. Is it “uniquely harmful” compared with sugar? The ongoing debate

You often hear:

“HFCS is more dangerous than sugar. If you must choose, sugar is better.”

But from a chemical standpoint, they’re actually quite similar:

Sugar (sucrose):
50% glucose + 50% fructose, chemically bound 1:1 as a disaccharide
Typical isoglucose (HFCS-55 / fructose-glucose syrup):
About 45% glucose + 55% fructose, mixed as free monosaccharides

So the glucose-to-fructose ratio is nearly the same, and once they’re in the body, most experts believe they behave similarly.

In the U.S., some drinks switched from HFCS to cane sugar and advertised this change,
but nutrition experts have consistently said:

“They are both sugar-sweetened beverages; the health effects are virtually the same.”

So rather than:

“Glucose-fructose syrup is the villain and sugar is safe,”

it’s more realistic to think:

Any type of added sugar is harmful in excess

That’s a practical and evidence-based way to see it.

4. HFCS and Disease: What Do We Actually Know So Far?

Now let’s look in a bit more detail at the diseases most strongly linked to HFCS and related sweeteners.

4-1. Obesity and metabolic syndrome

Many studies consistently show:

People who frequently and heavily consume sugar-sweetened beverages rich in glucose-fructose syrup / HFCS are more likely to be obese or have metabolic syndrome.

Possible reasons include:

Liquid calories are easy to consume without feeling full, increasing total energy intake
Fructose is readily converted to triglycerides in the liver, promoting visceral fat and fatty liver
Getting used to very sweet drinks may increase cravings for sweet foods in general

4-2. Type 2 diabetes and insulin resistance

Observational studies have often found that people who drink lots of high-fructose beverages:

Have higher risk of developing type 2 diabetes
Are more likely to develop insulin resistance (a condition where insulin becomes less effective)

However, rather than saying “HFCS causes diabetes,” it’s more accurate to note that:

Total calories consumed
Overall dietary pattern (fat intake, fiber, etc.)
Lack of exercise, poor sleep, and other lifestyle factors

all contribute significantly in addition to sugar type.

4-3. Non-alcoholic fatty liver disease (NAFLD)

Recently, fatty liver has become a major focus.

Several review articles from 2023–2025 have suggested that beverages high in HFCS:
- Promote accumulation of liver fat
- Increase liver inflammation
- Accelerate fibrosis (scar formation)
For people with obesity or type 2 diabetes, fatty liver progresses more easily and can lead to cirrhosis and liver cancer, so:

Cutting down on sweet drinks is a key step in protecting your liver.

4-4. Cardiovascular disease (atherosclerosis, heart attack, etc.)

People who consume large amounts of sugar-sweetened beverages (including those made with HFCS) tend to have:

Higher triglycerides
Lower HDL (“good”) cholesterol
Higher rates of high blood pressure
Higher risk of heart attacks and strokes

In 2024–2025, animal studies also suggested that HFCS may be involved in heart inflammation and myocardial damage.

The research is still evolving, but there is a growing consensus that:

We should cut back on sugar-sweetened beverages to protect cardiovascular health as well.

4-5. Inflammation, gout, and other issues

Inflammation
Diets high in sugar (including HFCS) tend to raise chronic inflammation markers (such as CRP), laying the groundwork for various lifestyle diseases.
Hyperuricemia and gout
Fructose metabolism generates uric acid, so overconsumption may raise the risk of hyperuricemia and gout.
Tooth decay
Like sugar, HFCS helps oral bacteria produce acid, which erodes tooth enamel.
Constant sipping throughout the day is particularly harmful.

5. Sugar vs. Glucose-Fructose Syrup: Which Is “Less Bad”?

Let’s address a common question more directly.

5-1. Calories and glycemic impact: “basically similar”

Calories:
Both sugar and isoglucose provide about 4 kcal per gram—essentially the same.
Blood sugar:
Small differences in fructose ratio can slightly change how blood sugar rises,
but in practice, drinking a lot of either will promote weight gain and worsen blood sugar.

Experts in the U.S. often say:

“Switching from HFCS to cane sugar offers almost no health advantage.
The key is how much you cut sugar-sweetened beverages overall.”

5-2. Differences in taste, cost, and handling

Glucose-fructose syrup
- Easy to handle as a liquid
- Fructose is sweeter, especially in cold drinks
- Doesn’t crystallize easily, ideal for beverages and sauces
- Inexpensive to produce in large quantities
Sugar (sucrose)
- Familiar taste, easy to use at home
- Solid form is easy to transport, but in industry it may require extra steps to dissolve

From a health standpoint, both are “free sugars” we want to reduce.
So the question isn’t really “Which is better?” but:

Can we choose products in a way that reduces total sugar intake?

That’s the crucial point.

6. How Japan, the EU, the U.S., and China Treat HFCS

6-1. Japan: strictly defined by JAS, not banned

As mentioned earlier, Japan’s JAS defines isoglucose in detail.

For example:

Clear categories for glucose-fructose syrup, fructose-glucose syrup, and high-fructose syrup
Fructose content thresholds for each
Quality standards like minimum sugar content and maximum ash content
Only starch as the raw material and no additives allowed

So quality is tightly regulated.
However, it is not treated as “banned due to health hazards.”
Like sugar, it’s positioned as a food ingredient we should not over-consume, while managing our overall diet.

6-2. EU & U.S.: Ingredient allowed, quantity curbed mainly via taxes and policies

EU
- Glucose-fructose syrups are treated as types of sugar.
- Historically, production quotas limited their share compared to sugar, but loosened rules have increased their use.
- At the same time, many countries now impose sugar or soft drink taxes, targeting all sugar-sweetened beverages, not just HFCS.
U.S.
- HFCS is recognized as a safe food ingredient by the FDA; it is not banned.
- However, various states and cities have introduced taxes on sugar-sweetened drinks to reduce overall consumption.

6-3. China and other regions

In China, starch-based sugar syrups are widely used and regulated under national standards (GB).
In Southeast Asia, you’ll see terms like “High fructose glucose syrup,” governed by each country’s regulations.

In all regions, the trend is less:

“Ban isoglucose itself,”

and more:

“Reduce free sugar intake overall.”

7. Practical Tips for Living with HFCS: Everyday Strategies

Now, let’s look at some concrete tips for keeping reasonable distance from glucose-fructose syrup, especially for everyday consumers.

7-1. How to spot HFCS on labels

If you see any of the following, it’s an isoglucose-type sweetener:

ぶどう糖果糖液糖 (glucose-fructose syrup)
果糖ぶどう糖液糖 (fructose-glucose syrup)
高果糖液糖 (high-fructose syrup)
砂糖混合ぶどう糖果糖液糖 (sugar-mixed glucose-fructose syrup), etc.

On imported products, you may see:

High fructose corn syrup
Corn syrup
Glucose-fructose syrup
Fructose-glucose syrup

Just by checking:

Whether these appear first or second in the ingredients list
Whether “sugar,” “isoglucose,” or “juice” is the main sweetener

you can get a rough sense of how sweet the product is and adjust:

“I had a lot of sweet drinks today—maybe I’ll cut back tomorrow.”

7-2. The most efficient step: reduce sweet drinks

WHO and many national experts agree that the first target when cutting sugar should be sugar-sweetened beverages.

Some simple steps:

Step 1: Limit your daily soda or sports drink to “one can/bottle per day”
Step 2: Make water, unsweetened tea, or plain sparkling water your default when thirsty
Step 3: When you want flavor:
- Dilute 100% fruit juice 2–3x with water or sparkling water
- Use sparkling water with a splash of lemon juice

Rather than “quitting completely,” thinking in terms of “cut a bit and substitute” is usually more sustainable.

7-3. Rough guidelines for children

Children are lighter, so the same amount of sugar represents a larger dose per kilogram of body weight.

A simple rule-of-thumb:

On a daily basis:
→ Water, barley tea, milk, and diluted fruit juice as staples
Sweet juice or sports drinks:
→ A few times a week, roughly one small glass (150–200 mL) per occasion
Sweet sodas:
→ Reserve for “special occasions” (weekends, events, parties)

It can help to set these as gentle household rules, rather than rigid bans.

7-4. “Slightly better” choices among processed foods

Completely eliminating sweet foods isn’t realistic. Instead, choose slightly simpler options within the same category.

Sweet breads
- From cream-, chocolate-, or jam-filled bread loaded with isoglucose →
  switch to anpan (sweet bean bread), plain rolls, or baguettes with fewer ingredients.
Snacks
- From colorful gummies or candies with isoglucose →
  switch to unsalted nuts, plain yogurt with a small drizzle of honey, or whole fruits.
Condiments
- From very sweet sauces or dressings where fructose-glucose syrup is the first ingredient →
  make simple sauces yourself (soy sauce + mirin + a little sugar), or choose “no added sugar” / “reduced sugar” products.

These small switches add up, and before you know it, your intake of glucose-fructose syrup can drop significantly.

8. Who Should Be Especially Careful, and Why?

8-1. People with obesity, metabolic syndrome, or fatty liver

If you already have visceral fat or fatty liver,
excess fructose (including from isoglucose) may worsen your condition.
If you drink sugar-sweetened beverages daily,
simply re-evaluating your drinks can be one of the most important steps you take to protect your liver and blood vessels.

8-2. People with diabetes or prediabetes

Glucose raises blood sugar directly; fructose promotes liver fat and triglycerides.
Beverages rich in glucose-fructose syrup can easily cause blood sugar “spikes” (rapid rises and falls), making them particularly risky for people with diabetes.

It’s wise to discuss with your doctor or dietitian and:

Avoid sweet drinks as a general rule
Decide realistic limits on quantity and frequency for the occasions when you do drink them

8-3. Children and teens

Growing kids need energy, but these years also shape their long-term sense of taste.
If sweet drinks and sweets are the daily norm from an early age, multiple studies show higher risks of future obesity, tooth decay, and lifestyle-related diseases.

Framing sweet treats as:

“An accent for fun times” rather than “everyday staples”

may be one of the best long-term gifts you can give them.

9. Summary: How Should We Think About Glucose-Fructose Syrup?

Let’s整理 the key points:

Glucose-fructose syrup is a type of isoglucose
Made from starch, it’s a liquid sugar composed of glucose and fructose.
Depending on fructose content, it’s classified as glucose-fructose syrup, fructose-glucose syrup, or high-fructose syrup.
The “High Fructose Corn Syrup (HFCS)” that’s been controversial in the U.S. is roughly equivalent to Japanese fructose-glucose syrups, and is widely used in drinks and processed foods.
Many studies have linked high intake of these sweeteners—especially via sugar-sweetened beverages—to obesity, type 2 diabetes, fatty liver, and cardiovascular diseases.
However, the health impact of sugar and glucose-fructose syrup is “basically similar”.
Rather than one being uniquely dangerous, WHO and most experts stress that:

The key is how much you reduce all free sugars, regardless of type.

In Japan, the EU, the U.S., China, and elsewhere, isoglucose is not banned,
but many places are moving toward reducing overall sugar-sweetened beverage consumption via sugar taxes and similar policies.
What we can do starting today:
- Get in the habit of spotting “glucose-fructose syrup” and “fructose-glucose syrup” on labels
- Make water, tea, or plain sparkling water your default choice when thirsty
- Treat children’s sweet drinks and snacks as “occasional treats,” not everyday necessities

All in all, glucose-fructose syrup is neither pure poison nor completely harmless.
It’s a convenient sweetener that can burden the body when consumed in excess.

There’s no need to be so afraid that you can’t eat anything at all.
But if you start glancing at labels, cutting out one sweet drink here and there, and making small tweaks, you’ll gradually shape a healthier relationship with sweetness.