The effect of fructose on human health has been the source of much controversy. This is because people are consuming more fructose than ever, due to the addition of sugar and high fructose corn syrup in processed foods.

Fructose is a natural sugar present in fruits, fruit juices, certain vegetables, and honey. In these forms, fructose sugars can be part of a nutritious diet.

However, fructose is also a component of high fructose corn syrup, which manufacturers make from corn starch and add to foods such as sodas and candies. These foods are less nutritious, but a person can eat them in moderation.

Researchers are studying the links between high fructose foods and obesity, diabetes, and even some cancers. However, some evidence indicates that fructose is not necessarily a public health concern when a person consumes it in moderation.

This article covers whether fructose is bad for health, the different types of sugar, and the research into their effects on the human body.

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Fructose comes from natural foods, such as honey or fruits, and it can be healthy as part of a balanced diet. However, people should limit their intake of processed forms of fructose, including high fructose corn syrup.

Some research suggests fructose can adversely affect a person’s health in several ways.

Obesity

Researchers in a 2017 literature review found evidence that consuming excessive amounts of fructose may lead to a greater risk of obesity and related conditions, such as metabolic syndrome.

They also found that excess fructose consumption may have links to an increased development of fat, as it may alter how the body breaks down fats and carbohydrates.

Moreover, fructose consumption could lead to increased food consumption, as it may not make people feel as full.

Learn facts and statistics about obesity.

Insulin resistance

The same 2017 review found excess amounts of dietary fructose seemed to cause inflammation that could lead to insulin resistance.

Insulin resistance means glucose can build up in the blood, causing a range of health problems, including type 2 diabetes.

A 2016 study discovered similar results. The research looked at the effects of fructose-rich drink consumption in those aged 12–16 years in Taiwan. People who drank more fructose-rich drinks had higher levels of insulin resistance.

Liver problems

According to the National Institutes of Health (NIH), fructose consumption could lead to an increased risk of nonalcoholic fatty liver disease. In this condition, the body stores too much fat in the liver cells.

The results of some studies have confirmed this finding, although others have stated there is no correlation.

Fatty liver disease can lead to liver damage and inflammation, which can lead to nonalcoholic steatohepatitis, a serious condition that can cause:

Colorectal cancer

Researchers in one 2021 study on mice found that consuming too much fructose can promote intestinal tumor growth.

A 2019 study, also on mice, had similar findings. Researchers wrote that in mice prone to developing intestinal tumors, high fructose corn syrup seemed to make the tumors more aggressive and cause them to grow faster, but they were not sure why.

The newer study found that the fructose did not cause the tumor cells to grow faster, but it caused them to survive for a longer time. Researchers also found that fructose made the mice with colorectal cancer more likely to experience anemia, which has links to lower survival rates in both mice and humans with the condition.

However, further studies on humans are necessary to confirm the effects of fructose on cancer.

Contrasting evidence

Although there is much evidence that excess fructose consumption has negative effects on health, it is difficult for researchers to separate the effects of fructose in the diet from those of other sugars.

This is because foods with high levels of added fructose usually also contain high levels of other sugars, such as glucose. Scientists conduct many research studies into the effects of fructose in rats fed combinations of sugars.

A 2014 literature review states that fructose does not have specific effects on the body that can cause weight gain compared with eating sugar from other sources.

The authors also argue that, while sugar-sweetened drinks contain fructose, they are also high in calories. This may explain some links between fructose and obesity.

To date, the Food and Drug Administration (FDA) says it is not currently aware of any evidence that foods containing high fructose corn syrup are less safe than other foods containing similar sweeteners, such as sucrose and honey.

The FDA lists high fructose corn syrup — the most controversial of the fructose-containing foods — as safe to eat.

However, people should limit their intake of all added sugars, including high fructose corn syrup and sucrose.

Fructose is a very sweet, naturally occurring caloric sweetener. It can come from fruits, fruit juices, honey, and even some vegetables.

Pure fructose is also much sweeter than other types of sugar. As a result, people can use less fructose than other sugars in cooking to achieve the same sweetness.

The most significant sources of fructose in the diet include:

  • table sugar
  • honey
  • agave nectar
  • fruit juices
  • high fructose corn syrup, which is present in candy, baked goods, and sodas, and other processed foods

High fructose corn syrup

Manufacturers create high fructose corn syrup by adding certain enzymes to corn starch, which is essentially pure glucose, another type of sugar. They then use this glucose to create a syrup that contains varying amounts of fructose.

Most varieties of high fructose corn syrup contain either 42% or 55% fructose and 58% or 45% glucose. This means high fructose corn syrup contains slightly more fructose than table sugar, which is 50% fructose and 50% glucose.

Honey is another common food additive. The substance often contains a 1-to-1 ratio of fructose to glucose.

Fructose can bind to glucose to make sucrose, or table sugar.

Unlike fructose, the body largely breaks glucose down in the cells. The small intestine usually absorbs this sugar and sends it out to the body’s cells for energy. The body digests fructose with glucose more easily than fructose alone.

When a person consumes glucose, the chemical structure of the compound triggers the pancreas to release insulin, a hormone that allows cells to use glucose for energy.

Fructose does not trigger insulin release or the release of hormones, such as leptin, which tells the brain that a person is full. It also does not inhibit hormones that tell an individual’s body that they are hungry.

As a result, fructose may lead to weight gain because it may contribute to overeating.

In a 2017 study on mice quoted in the NIH news archives, researchers split mice on a standard, low fat diet into two groups. One group received added glucose and the other fructose. Both groups of mice gained weight. However, the rodents on a high fat diet that received fructose gained significantly more weight than mice on the same diet with added glucose.

There are two types of fructose: naturally-occurring fructose and high fructose corn syrup. The body digests both in the same way.

Examples of natural foods naturally high in fructose or fructans, which are long chains of fructose, include:

  • agave syrup
  • apple juice
  • apples
  • caramel
  • dry figs
  • honey
  • licorice
  • molasses
  • pears
  • prunes
  • sorghum

Some vegetables contain fructose, but this is usually in smaller amounts than fruits. These include:

  • asparagus
  • chicory roots
  • Jerusalem artichokes
  • leeks
  • onions

Fructose in processed foods

A person wishing to reduce their intake of dietary fructose and fructans should avoid food with the following sweeteners:

  • high fructose corn syrup
  • caramel
  • honey
  • molasses
  • palm sugar

A person should limit their consumption of foods that commonly contain high fructose corn syrup. These include packaged baked goods, candy, and sweetened drinks.

Learn more about sources of high fructose corn syrup.

Fructose is naturally present in many fruits and vegetables, which people can include as part of a nutritious, balanced diet.

The FDA states fructose is a safe ingredient to add to foods. It adds that there is not enough evidence to say the substance is less safe than other similar sugars, such as sucrose and honey, but it recommends limiting all added sugars.

When people eat or drink lots of high fructose foods, such as sugar-sweetened beverages, they are also taking in extra calories that can contribute to weight gain.

There is no recommended daily minimum or maximum fructose intake because a person does not need this sugar to survive. Manufacturers add fructose to foods as a sweetener, but it has little nutritional value.

Where possible, doctors recommend that people eat fresh, whole foods and avoid frequently eating foods with added sugars.