Fructose is a natural sugar that is present in fruits, fruit juices, certain vegetables, and honey. In these forms, fructose sugars can be part of a healthful diet.
However, fructose is also a component of high-fructose corn syrup (HFCS), which manufacturers make from corn starch and add to unhealthful foods such as sodas and candies.
Researchers are studying the links between high-fructose foods and obesity, diabetes, and even some cancers. However, there is also some evidence that indicates that fructose is not necessarily a public health concern when a person consumes it in moderation.
In this article, we will cover whether fructose is bad for health, the different types of sugar, and the research into their effects on the human body.
What is fructose?
Fructose is a natural sugar present in fruit and honey.
Fructose is the sweetest of the naturally occurring caloric sweeteners. Fructose occurs naturally in fruits, fruit juices, honey, and even some vegetables.
Pure fructose is 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
- agave nectar
- fruit juices
- HFCS, which is present in candy, baked goods, and sodas, and other processed foods
Manufacturers create HFCS by adding certain enzymes to corn starch, which is essentially pure glucose. Glucose is another type of sugar. They then use this glucose to create a syrup that contains varying amounts of fructose.
Most varieties of HFCS contain either 42 or 55 percent fructose and 45 percent glucose. This means that HFCS contains the same amount of fructose as sucrose, or table sugar.
Manufacturers make table sugar from a combination of fructose and glucose.
Honey is another common food additive. Honey contains a 1-to-1 ratio of fructose to glucose.
Is fructose bad for you?
Natural fructose from fresh fruit and vegetables is good for a person's health. Processed forms of fructose, such as HFCS, may have negative health effects. Scientists are currently studying how this type of sweetener compares with other forms of sugar.
Below, we discuss the research around the possible risks and benefits of fructose on a person's health.
The evidence against fructose
Consuming large amounts of fructose may put a person at greater risk of obesity.
Some researchers believe that the body processes fructose differently than other types of sugar.
In particular, there are concerns that when a person consumes fructose in excess, it may stimulate the body to deposit extra fat, especially in the liver. This may contribute to nonalcoholic fatty liver disease.
According to a 2017 literature review, eating excessive amounts of fructose is associated with:
- inflammation that could lead to insulin resistance
- an increased development of fat, as it may alter the ways that the body breaks down fats and carbohydrates
- a greater risk of obesity and related conditions, such as metabolic syndrome
- greater food intake, as it does not make people feel full
A 2016 study 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, which is a marker for hardened arteries, diabetes, and heart disease in adults.
The evidence for fructose
Although there is evidence that excess fructose consumption is bad for health, it is difficult for researchers to separate the effects of fructose in the diet from those of other sugars.
This is because foods that contain 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 when 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 United States Food and Drug Administration (FDA) say that they are not currently aware of any evidence that foods containing HFCS are less safe than other foods containing similar sweeteners, such as sucrose and honey.
The FDA list HFCS, the most controversial of the fructose-containing foods, as safe to eat.
However, people should limit their intake of all added sugars, including HFCS and sucrose.
Fructose vs. glucose
Fructose can bind to glucose. Fructose plus glucose is called sucrose, or table sugar.
Unlike fructose, the body largely breaks glucose down in the cells. The small intestine usually absorbs this sugar type and sends it out to the body's cells for energy. Researchers usually regard glucose as the body's preferred carbohydrate source for energy.
When a person eats 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, nor does it trigger the release of hormones such as leptin, which tells the brain that a person is full, or inhibit hormones that tell a person's body that they are hungry.
As a result, researchers suggest that fructose is more harmful to a person because they are more likely to eat more than if they had eaten a food containing glucose.
However, a person should remember that foods with glucose-containing sugars still have calories. Excess calorie intake can lead to weight gain.
Sources and types of fructose
Pears are naturally high in fructose.
Two fructose types exist: naturally occurring and HFCS. The body digests both the same way.
Examples of natural foods that are naturally high in fructose include:
- agave syrup
- apple juice
- dry figs
Some vegetables contain fructose, but this is usually in smaller amounts than fruits. These include:
- chicory roots
- Jerusalem artichokes
Fructose is naturally present in many fruits and vegetables, which people can include as part of a healthful, balanced diet.
Researchers are still debating whether various forms of fructose are bad for people's health. The FDA state that fructose is a safe ingredient to add to foods.
They believe that there is not enough evidence to say that fructose is less safe than other similar sugars, such as sucrose and honey, but they recommend 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 minimum or maximum intake of fructose daily 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.