Fructose Definition, Sources, and Health Effects

close-up of spoon in a small bowl of sugary syrup
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Sugar has long been a household staple sprinkled over cereal, stirred into coffee, or borrowed from a neighbor in a baking emergency. You used to have just two types of sugar to choose from, white or brown. Since sugar was either kept in a bowl on the table with a spoon or measured out carefully for baking, it was also easy to control sugar intake.

Today, sugar can take several different forms, and many foods contain added or hidden sugars. This is especially true of packaged and processed foods. As a result, people often don't realize how much sugar they regularly consume.

One of the most common forms of sugar is fructose. Understanding what fructose is, how it’s used, where it’s found, and what health effects it can have will empower you to make educated choices about what to eat.

Fructose Definition

The white sugar (granulated sugar) in your pantry is known as sucrose, which is made of two simple sugar molecules: glucose and fructose. Any foods that contain sugar will have fructose in them. Fructose in a monosaccharide and is the main natural sugar found in fruits and vegetables. If fructose is refined it turns into high fructose corn syrup.

Both sucrose and fructose are refined from natural sources. Sucrose comes from plants, like sugar cane, and small amounts of fructose are found in berries, melons, and apples. It's also found in certain vegetables, including beets, sweet potatoes, and onions.

Fructose Sources

While intake of fresh produce is an essential component of a balanced meal plan, when consumed in excess, the body cannot process fructose effectively. However, it is very unlikely that someone would consume too much fructose from natural sources.

Seventy-four percent of the food products we eat have added sweeteners—and not just those with a sweet taste. Added sugars can be found in everything from bottled salad dressing to ketchup.

Years ago, the eating habits of the average American looked (and tasted) very different from what we’re accustomed to today. In the early 19th century, the average American consumed about two pounds of sugar in an entire year.

In 1999, sugar consumption by the average American peaked, in large part due to the growing presence of added sugars. Americans were eating about 26.7 teaspoons of sugar, or about 112 grams, per day. (This figure doesn’t include non-caloric sugar substitutes like aspartame).

Today, a person living in the U.S. consumes an average of 77 grams of sugar a day, which equals a staggering 60 pounds per year. Sugar intakes for children are even higher. A typical child in America consumes 81 grams of added sugar per day or 65 pounds per year. Much of this added sugar comes from beverages, with most kids drinking up to 30 gallons of sugary drinks annually.

In fact, sugar-sweetened beverages like soda and energy drinks are one of the main ways people of all ages ingest added sugars. Another factor contributing to increased consumption is larger portion sizes, especially in drinks purchased at fast food establishments or in larger bottles sold in bulk at the grocery store.

Health Effects of Fructose

In recent decades, we’ve learned more about the potential health effects of increased consumption of all types of added sugars, and of fructose specifically. We know that excess added sugars are linked with risks like obesity, heart disease, and type 2 diabetes. Some scientists think fructose is especially dangerous, though research hasn't confirmed this yet.

Fructose Metabolism

The body can't use fructose as efficiently as it uses glucose, the sugar that is the body's main source of fuel. Most carbohydrates we eat are made up of chains of glucose. When glucose enters the bloodstream, the body releases insulin to help regulate it. Insulin allows the glucose to enter cells, where it's used for energy.

Fructose, on the other hand, needs to be processed by the liver first. In small amounts, the liver can handle fructose effectively. But when too much fructose reaches the liver all at once, it has trouble metabolizing the sugar fast enough. That's where possible health risks come in.

Fructose Risks

One of the ways the liver tries to handle the excess is by converting the fructose into fat. This can lead to a condition called nonalcoholic fatty liver disease, which causes liver inflammation and damage. The damage can make the liver function less efficiently.

The fats produced by the liver also can enter the bloodstream in the form of triglycerides. Elevated levels of triglycerides are a risk factor for heart disease. Furthermore, excess fructose consumption can also raise levels of LDL cholesterol and may facilitate insulin resistance, which can eventually lead to type 2 diabetes.

In addition, it's thought that excess levels of fructose in the bloodstream can lead to the buildup of a substance called uric acid. Too much uric acid can cause gout and kidney stones.

Several studies have demonstrated the way fructose affects the body’s appetite-regulating system. Fructose is suspected to work as a driver of obesity because it fails to trigger the hormones responsible for sending “I’m full!” signals. Genetic mutations may make some people more susceptible to weight gain related to fructose intake.

More Added Sugar Risks

Whether or not fructose has unique risks, it's still a major source of added sugars, which have known dangers in adults and children. Once you've eaten enough sugar to meet your body's energy needs, the body doesn't have another immediate use for the extra sugar.

When excess sugar is present, the body's organs and tissues will try to compensate. This can result in elevated levels of lipids and glucose in the blood, which can increase a person's risk for metabolic diseases. It might also raise the risk of cognitive decline.

While sugar is often implicated in cancer risk, the link between sugar and cancer is more indirect. The health effects of consuming excess sugar, particularly weight gain and insulin resistance, may increase a person's risk for certain types of cancer.

A newer theory is that, when the colony of bacteria living in your intestines freely feeds on sugar, it can upset the balance of healthy gut flora. High sugar intakes appear to decrease the diversity of gut bacteria, favoring pro-inflammatory species, and reducing levels of "good bacteria." This alteration is suspected to impair immunity and increase our susceptibility to other health issues.

High Fructose Corn Syrup

Fructose is commonly added to processed foods because it's less expensive to produce than sucrose and less is required to achieve the same level of sweetness. As a standalone sweetener, fructose is nearly 1.8 times as sweet as table sugar.

It often takes the form of high fructose corn syrup (HFCS), which is fructose combined with chemically-treated corn syrup that has been altered to increase its concentration and sweetness. Since fructose has a low glycemic index (meaning it does not cause high spikes in blood sugar), it was once believed fructose was a better choice than regular table sugar.

However, several epidemiological studies have linked the availability of HFCS in the food supply to increasing rates of obesity and diabetes. Community programs and public health initiatives aimed at reducing HFCS intake have led to a plateau in obesity and diabetes rates.

Experts are still debating whether HFCS is worse for your health than other types of sugar. Whether or not it's uniquely bad, it's in some processed foods, making it one of the sources of sugar in the typical Western diet.

Manufacturers claim HFCS is about 55% fructose and 45% glucose. When tested, however, the exact composition seems to be closer to 60% fructose to 40% glucose.

More natural sources of sugar have various ratios, too: Honey has about the same fructose/glucose ratio as high fructose corn syrup and agave syrup can be up to 90% fructose. Fruit juice concentrates, which are often used as sweeteners, can have high amounts of fructose and tend to be highly processed. Processing strips away fruit's nutritional value. 

Whether it comes from corn syrup, fruit, or honey, your body handles fructose in the same way. The amount you consume makes the difference and can impact your health.

Average Fructose Content (in grams)
One can of regular (non-diet) soda 23 grams
Super size fountain soda 62 grams
*using the 55% fructose standard.

How to Reduce Sugar Intake

The American Heart Association recommends limiting daily added sugar intake to 6 teaspoons a day (or 25 grams) for women and 9 teaspoons (or 37.5 grams) for men. This refers to added sugars, not naturally occurring ones.

In reality, the average American consumes much, much more sugar each day. With many of those sugars hidden, it’s easy to underestimate how much you’re eating. In fact, unless you regularly check nutrition labels, you may not even be aware that many of the foods you eat even have added sugar.

Due to corn subsidies in the United States, HFCS is cheap to produce in large quantities, which accounts somewhat for its abundance in the modern American diet. Some of the most common sources include:

  • Baked goods
  • Cereals and cereal bars
  • Condiments
  • Frozen foods and dinners
  • Salad dressings
  • ​Sugar-sweetened beverages (the largest dietary source)
  • Sweetened yogurt

Once you become more aware of the sugar content of the food and drinks you consume each day, there are some steps you can take to reduce your sugar intake.

  • Reach for fresh fruits and veggies when you need a quick snack or midday pick-me-up.
  • Swap out soda for water, flavored seltzer, or plain seltzer mixed with 100% fruit juice.
  • Sweeten unsugared cereals with fresh fruit.
  • Watch out for foods labeled "fat-free," as these are often loaded with extra sugar to make up for the loss of flavor that occurs when fat is removed from the recipe.

A Word From Verywell

Reducing sugar consumption is a process. You don’t have to cut it out all at once. Take it slow and make mindful swaps to help your tastebuds develop a preference for foods that aren’t overly sweet. Reducing sugar intake stands to benefit your health in several ways. One small change at a time can add up to significant health effects over time.

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