Is Fructose Dangerous? Sorting Through the Facts and Hype

SO Delicious Minis Sweetened with Agave
was much better than I thought they would be!

Fructose generates a lot of debate and controversy within the low-carb community and other health groups, but there is very little real research to back up the various theories.

Those who have a vested interest in getting a particular outcome fund most scientific studies.

Silly conspiracy theory, perhaps, but that idea grows more plausible every time I watch the low-carb gurus, supporters, and research funders do exactly that: defend or twist a study’s outcome to prove what they want you and me to believe.

I ran into some agave-sweetened dairy-free ice cream bars at the grocery store when I first wrote this post. Since I was dairy free back then, I came home and decided it was time to take a closer look at fructose.

Not just at what the:
  • low-carb folks
  • diabetics
  • vegans
  • paleo
supporters preach and suggest (although I did do that), and not what the medical community and big pharma supported medical websites teach (I did that too); but I actually took the time to dig into the scientific studies for myself and read what researchers and their data had to say about fructose.

Fructose Studies Use Intakes of Up to 50% of Daily Calories

I must have looked at a dozen research studies before giving up.

I could not find a single study that did not use an overly excessive amount of fructose to get the results they wanted.

A very high intake of fructose (35% to 50% of daily calories) first filled up the glycogen-depleted storage cells in the liver or muscles of the participants, and then the liver turned the rest of the carbohydrates into triglyceride and stored them in the liver or fat cells.

This is what the body does with all excess carbohydrates.

It isn't specific to fructose.

With that much fructose being eaten on a daily basis, the glycogen stores would always stay full. In that condition, there was no need for those carbs to be turned into glycogen, so all of it got turned into liver fat and body fat.

The same thing would have happened even with nutrient-dense carbohydrates.

Interesting Facts About Fructose

I ran into some interesting facts about fructose.

Apparently, the body doesn’t directly burn fructose for energy. It only burns glucose or fatty acids, so fructose has to be processed like any other carbohydrate.

The bottom line is that fructose is converted into glycogen or body fat, with a preference for glycogen, since glycogen can be quickly turned into glucose when the body needs it to keep your blood sugar steady.

Fructose is only turned into body fat when glycogen storage is full.

Fructose is the sweetest carbohydrate of all the sugars.

It is almost 1-3/4s sweeter than sugar is, so you don’t need to use anywhere near as much.

When I was on the low-glycemic Sugarbusters Diet, I used to use half as much as the sugar amount called for in the recipe.

Bowl of Strawberries and Purple Grapes
Fresh fruit contains 50 percent glucose
and 50 percent fructose in a non-concentrated form.

Low-glycemic diets like the Sugarbusters Diet are not opposed to fructose like low-carb diets are because fresh fruit contains both glucose and fructose in its natural form.

The problem with powdered crystalline fructose is that it's an extremely concentrated and highly processed carbohydrate, but so are all other sugars.

In fact, both table sugar and crystalline fructose have 4.2 carbs per level teaspoon, about 16 to 17 calories. The difference is that sugar is absorbed in the small intestine and fructose is absorbed through the stomach wall.

For that reason, fructose doesn’t spike blood glucose levels, since it doesn't have to be broken down during digestion, nor does it generate much of a second-phase insulin response after eating it.

What has people screaming about it is that unlike table sugar, fructose is processed in the liver, so the body is more likely to store excess fructose as liver fat rather than body fat if you eat too much of it.

The Sugarbusters Diet severely limited the amount of fructose you could eat, so excess storage was never a problem. Most people only used it to make their homemade stone-ground whole-wheat bread. People doing Sugarbusters were not addicted to fake treats. They just ate real food.

What Foods Contain Fructose?

Most of us know you can find fructose in:
  • fruits
  • processed foods
  • and baby foods
What you might not know is that you can also find high levels of fructose in almost all non-starchy vegetables, not just carrots and other roots.

There are also various levels of fructose in many typical healthy foods:
  • Italian, Ranch, and Thousand island salad dressings
  • fast food hamburger patties and grilled chicken
  • eggs
  • whole milk mozzarella cheese and Parmesan cheese
  • corned beef, ham, bacon, and pastrami
  • artichokes
  • avocados
  • fresh tomatoes
  • tomato juice, tomato sauce, spaghetti sauce, and catsup
  • balsamic and cider vinegar
  • bell peppers (both green and red)
  • lettuce, all types
  • spinach and turnip greens
  • onions
  • cucumbers and pickles
  • summer and winter squashes
  • cabbage, both green and red
  • sauerkraut
  • brussels sprouts
  • asparagus
  • green beans
  • mushrooms
  • okra
  • beets
  • broccoli
  • celery
  • carrots
  • peas
  • edamame
  • lime juice
  • yellow mustard
  • Miracle Whip salad dressing
  • mayonnaise
  • nuts
  • coconut
  • spices: paprika, chili powder, ground ginger, cinnamon, cloves, basil, oregano, curry, parsley, turmeric, and poppy seeds
In addition, most carbohydrates contain only very small amounts of fructose:
  • sweet potatoes
  • corn, popcorn, and cornmeal
  • potatoes, white and red
  • beans and lentils (including lima beans)
  • multi-grain bread
  • wheat, teff, buckwheat groats (kasha)
  • rice and pasta
What this means is that there’s some amount of fructose in all processed foods including low-carb staples like:
  • Dreamsfield pasta
  • Carbolose flour
  • Carbquick bake mixes
  • low-carb tortillas and flatbreads
Unless you plan to go on a no-carb diet and eat only unprocessed meats, there’s no getting away from fructose.

So What’s the Hype All About? Why Are People So Afraid of Fructose?

What studies have shown is this:

Since fructose can’t be used directly for fuel and most Americans are prone to overeat carbohydrates, most of the fructose they eat gets turned into triglycerides by the liver and stored in the liver or fat cells.

A fatty liver results in:
  • insulin resistance
  • metabolic imbalances
  • possibly inflammatory diseases
Excess fructose can also cause:
  • glucose and fructose malabsorption problems
  • a greater amount of triglycerides in the blood
  • and higher total cholesterol levels
The kicker still circles back around to the fact that these studies don’t use a typical amount of fructose or the amount that would be consumed by the average individual. They are constructed to show what happens when a person eats excessive amounts of fructose.

All these studies show is what happens when you overeat fructose on a regular basis.

Americans eat a lot of high fructose corn syrup, but they still don't eat anywhere near 35% to 50% of their daily calories from fructose alone.

In fact, one study published in Nutrition and Metabolism in 2005 set the line for danger at 25% of your daily calories. That is a lot of fructose you have to eat before metabolic damage appears, especially when you consider that typical sweeteners like table sugar are only 50% fructose.

The other 50% is glucose, which can be used directly for fuel when available.

We’re talking 500 calories of pure fructose.

That's over 2-1/2 cups of the crystalline stuff per day. Are you really eating 500 calories of veggies or even 1,000 calories (5 cups) of sugar a day?

Demonizing Fructose Makes No More Sense than Demonizing Carbs

If you look at Alan Aragon’s blog post where he discusses some research put out by the USDA Economic Research Service, the data presented on what actually fuels obesity is extremely enlightening.

In 1970, for example, back when Dr. Atkins published his first diet book, the average calorie intake was 2,172. That is where the idea originated that a typical woman needs 2,000 calories per day to maintain a healthy weight.

But the USDA data also shows that in 2007, the average calorie intake had risen to a whopping 2,775! 

That’s an increase of over 600 calories per day!

In addition, the Economic Research Service came up with no individual category rising enough to blame all of those excess calories on. In other words, we are overeating everything now. 

Yet, we’re running around trying to blame:
  • carbohydrates
  • fructose
  • fat in our food
  • hypothalamus
Instead of taking a serious look at how much we're eating.

We’re blaming everything in our environment except ourselves.

Yes, environmental toxins are real, genetic damage is possible, and the body can malfunction and create all kinds of havoc. Heredity also sets us up for a lot of grief. 

But as long as we keep demonizing everything outside of our self and refuse to look at the portion sizes we are eating, we’ll never be able to take the steps necessary to correct how we got so far off course.


  1. Okay so you write an article telling us how bad fructose is, give us the false impression that it cant be used for energy and is stored as fat.. Tell us its in everything... Then do a complete u turn and say there is nothing to worry about. I worry.... About writers like you!!

  2. An article demonizing high-fructose corn syrup WHERE???? This post is about how your body actually metabolizes fructose. It's stored in the liver as glycogen and only turned into body fat if you eat more than you can store. I have no idea what you are talking about when you say it can't be used for energy and is stored as fat. The only article I've written about fructose at my low-carb blog was about mercury that's been found in some sources of HFCS. The low-carb community is afraid of HFCS, but I have never said anything even close to that. Maybe you need to reread my post again.


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