No doubt you’ve heard about fructose. Is it better than glucose? Is it “bad”? Do you have any idea whether there is a difference? Does it really matter? Like most things we talk about, fructose is not inherently bad. After all humans have been consuming it in fruits and vegetables since the dawn of time. But also like most things we talk about, issues arise when there’s an excess. And unfortunately, our industrial food system loves to up the fructose content of our food. Our body then has to deal with that imbalance and excess. So let’s dive in to talk about what that means and why it matters for you and your health.

What is Fructose?

Like glucose, fructose is a simple sugar. It’s commonly found in honey and fruits, as well as foods that contain high fructose corn syrup like sodas, breakfast cereals, and candy. 

It’s a monosaccharide, which means it’s a sugar in its simplest form. It cannot be broken down any further. When it bonds with glucose, it becomes sucrose — the sugar we think of as sugar. 

Fructose vs Glucose Metabolism

Our body handles glucose and fructose very differently. The biggest difference between glucose and fructose is how the body metabolizes each. Metabolism is simply the process by which your body converts what you eat or drink into energy. You can learn more about glucose metabolism here, but the short version is that cells all over your body can use glucose as fuel— your muscles, your brain, your heart, etc. Your liver pulls the excess glucose out of your blood stream and can store it as glycogen, turn it into fat for storage, make cholesterol, and other cool stuff.

Fructose, on the other hand, is not a major energy source for most cells. In fact, the liver has to metabolize over 70% of fructose that you consume. In moderate amounts, this is totally fine. Fructose can go through a similar process as glucose to make energy for the liver. And it can be converted to glucose derivatives and then stored as liver glycogen.

However, the liver only needs so much energy and can only store only a certain amount of glycogen. So, when there is excess fructose, the liver has to figure out what to do with all of it.  As a result, fructose is often stored as fat.  In fact, excess fructose in the liver actually turns on the machinery that converts sugar to fat and has it working in overdrive. 

Fructose is Everywhere

People have been eating fructose forever. It’s in fruits and vegetables. It’s half of table sugar. there is no need to demonize all fructose! It’s the amount of fructose in our modern diets that is a problem. To put it into perspective just how much more fructose we are consuming, the average American consumed about 15 grams of fructose a day in the early 1900s. Today, we easily average 60-75 grams a day.

It isn’t just that we are eating more added sugar. Today’s food products are full of high concentrations of fructose. For example, high-fructose corn syrup describes corn syrup that has been processed to have a higher-than-natural fructose concentration. They process the heck out of corn to make a syrup with a concentration of fructose that is higher than natural. It’s sweeter and a cheap alternative to other sugar. As a result, high fructose corn syrup is everywhere! Don’t believe me? Go look at some of the items in your fridge. Start with the ketchup. Or that “healthy” flavored oatmeal. Or that can of Campbell’s soup. The list goes on.

It’s also in our sweets where we would expect to find plain sugar, now they often have a excess fructose. It’s in candy, popsicles, pop tarts... Basically, if it is ultra-processed and sweet, it probably is extra high in fructose. I was given an ice cream cup after a run the other day. You expect ice cream to have sugar, but high-fructose corn syrup? Why!?

The Health Impacts of Too Much Fructose

Researchers are still trying to understand the full impact of high fructose intake, especially in the form of high fructose corn syrup. Current studies have found an association with heart disease, cancer, diabetes, nonalcoholic fatty liver disease, and obesity. But scientists are unsure whether the health issues are related to the fructose specifically or the extra (un-filling) calories and the high palatability that go hand-in-hand with many products containing high fructose.  l

The scientific evidence is growing concerning the relationship of one disease: nonalcoholic fatty liver disease.  The link between high levels of fructose and risk of developing nonalcoholic fatty liver disease is strong.  This condition can progress to nonalcoholic steatohepatitis and then liver cirrhosis, liver failure, or liver cancer. Given what you have just learned about fructose metabolism, this makes sense.  The liver metabolizes most of the excess fructose you consume, and most of it is stored as fat. 

Studies have also confirmed that a high intake of fructose may reduce the production of leptin.  Leptin is the hormone that makes us feel full and helps regulate our energy balance. A decrease in leptin can make you really hungry, like eat your arm hungry. This makes it nearly impossible to regulate your food intake because you never quite feel full.  The result? Your body is constantly telling you that you are starving when you don’t actually need the calories. This results in unwanted weight gain (and a lot of frustration).

Managing the Fructose in Our Diets

Fructose isn’t inherently bad– what matters is how much you are consuming and what you are consuming with it. The fructose found in fruits is accompanied by important fiber and nutrients that our bodies need. The fiber may slow some of the absorption, giving your body time to metabolize it and not overload your system.  Whole fruit has also not been processed to increase the amount of fructose (though one may argue that it may have been grown and bred to have more fructose – a topic for a different day).  High fructose corn syrup, however, doesn’t have the same benefits. These highly concentrated levels of fructose are designed to be absorbed quickly, overloading your liver.

HFCS has become increasingly impossible to avoid. Gone are the days when it was only found in fast food and dessert. Now it’s in almost everything, from ketchup to chicken patties. To keep the flavor we crave in our food, some companies are in the process of creating a ‘healthier’ alternative to HFCS. But the best bet is to eat whole, unprocessed foods as much as possible. 

Want some support in creating a diet rich in the foods that fuel your body? I’d love to help— let’s talk.