Sweet Talk, Part 3: 9 Reasons Fructose Is Bad For You (FAK Friday)

Sweet Talk: 9 Reasons Fructose Is Bad For You

I don’t know about you, but I’m tired of seeing all these articles trying to tell us which foods we should eat, or which foods we should avoid. You know the ones I’m talking about; the “6 foods you should be eating to lose weight fast”, and the “5 foods you think are healthy, but actually aren’t”, or the “top 10 superfoods for perfect abs”. If you listen to these trends, peanut butter is a belly-blasting superfood one day, and a fat causing junk-food the next. The information is based in reality similar to a movie that’s based on a true story — it is biased, over-blown, and often times out of context.

Writing this post, I found myself doing something very similar. We’ve all heard that “High-fructose is bad!”, but what I wanted to do was trace those claims to their source and decide for myself. Unfortunately, truths are complicated, and facts are often very hard to distinguish from fiction.

As a disclaimer, I’m not going to pretend that I am not biased, and I won’t lead you on to think I am something I’m not. I am not a nutritionist, a dietitian, a scientist, or a professional researcher. But I do care, and this week my focus was to sort out some of the information that’s out there and try to understand it better for myself. I encourage you be skeptical, ask questions, and draw your own conclusions.


First, let’s take a look at what fructose is.

There are dozens of different sugars in the world, but for the purpose of this article what we need to understand are sucrose, glucose, and fructose. Sucrose (aka, table sugar) is a disaccharide — this means it is made up of two sugar molecules joined together. These two molecules on their own are called glucose and fructose.

Glucose, besides being present in sugar, honey, and other sweeteners, is derived from starch — when we eat starches, our bodies convert them into glucose which we use for energy. The body metabolizes glucose in the intestinal tract, where it gets absorbed into the blood stream causing a rise in blood sugar levels. To get the sugars where they need to go, the pancreas releases insulin, which binds to the glucose molecules and carries them off to the cells that need the energy most (and, if there is excess glucose, carries it off to be stored as fat). Glucose is the body’s number one source of energy, and is an important part of healthy functioning (in moderation).

Fructose is a naturally occurring sugar present in fruit, honey, and cane sugar, among other things. Fructose is about twice as sweet as glucose. It is often thought of as a healthier type of sugar because it has a low glycemic index, meaning it has a very small impact on blood glucose and insulin levels. This is because fructose doesn’t get absorbed in the intestinal tract the way glucose does. Instead, fructose travels further down the intestines and on to the liver. The breaking down of fructose in the liver triggers the production of uric acid, among other things, which may be harmful in large amounts.

Before cane sugar, and more recently high-fructose corn syrup, humans didn’t have a whole lot of access to either of these sugars. The fructose available to us was found in things like fresh fruit and berries, dates and figs, honey, etc. — things which were typically only available in limited amounts. Glucose in our diets came primarily from starches and carbohydrates like wheat and other grains, which our bodies converted to energy.

Now a’days, we get most of our sugars from cane sugar, corn syrup, and high-fructose corn syrup. In cane sugar, glucose and fructose are paired with one another — it is 50% glucose and 50% fructose. Corn syrup is made by treating corn starch with enzymes, which convert the starches into glucose the same way our bodies would. Regular corn syrup is almost entirely glucose. High-fructose corn syrup (or HFCS) has  been treated with more enzymes, which convert some of the glucose into fructose. HFCS is commonly believed to contain 55% fructose, but studies now show it can range anywhere from 55% fructose to 65% fructose, if not more.


In part one of this series, Cane Sugar and How It’s Made, I mentioned how much sugar consumption has increased in our diets over the past hundred years. In the 1800’s, humans consumed approximately six pounds of sugar per person per year, compared to an estimated 130 pounds per person per year today. A big player in this increase is high-fructose corn syrup, which was introduced to the market in the late 60’s. According to the US Department of Agriculture, consumption of HFCS increased more than 1000% between 1970-1990, and now constitutes more than 40% of all added sugars.

“Since 1985, an American’s annual consumption of HFCS has gone from forty-five pounds to sixty-six pounds. You might think that this growth would have been offset by a decline in sugar consumption, since HFCS often replaces sugar, but that didn’t happen: During the same period our consumption of refined sugar actually went up by five pounds. What this means is that we’re eating and drinking all that high-fructose corn syrup on top of the sugars we were already consuming.” – Michael Pollan, The Omnivore’s Dilmma

The invention of HFCS was a huge boon to the food industry, because it was much cheaper to produce than sugar. It was also much sweeter than regular sugar, meaning that manufacturers could use less of it to get the same results. Instead of cutting the cost of their products, however, many companies chose to simply sell more of the product per package.

A good example of this is when soft drink manufacturers switched from using cane sugar to corn sugar. Because the price of corn was so much cheaper, the cost of the beverages plummeted… but instead of lowering prices, companies like Coca-Cola and Pepsi decided to increase the size of their product, and switched from selling 8oz bottles and cans to 12oz (and later even larger sizes). The price per ounce fell, but the number of ounces sold increased. This is the same logic behind McDonald’s famous ‘supersized’ menu, which states that people are more likely to buy (and consume) one larger portion than they are to buy two of a smaller portion.

Some studies also suggest that an increase of fructose in the diet can mess with the body’s production of the hunger-regulating hormone leptin. This, along with findings which show sugar to be a highly addictive substance, may account for why so many people have trouble controlling how much they eat. From the standpoint of manufacturers, this is a good thing, because it means people will buy more of what they’re selling.

But it isn’t just soft drinks and candy companies that are making their fortune selling us cheap, corn laden products. High-fructose corn syrup is hidden in most mass-market breads, yogurts, breakfast cereals, low-fat foods, “health” bars, and more. I was recently fooled by a nutri-grain bar which boasts the words “no high-fructose corn syrup!” on the front of the package, but on closer inspection contains not only sucrose and corn syrup, but also fructose. No high-fructose corn syrup, but corn syrup and fructose.

It’s easy to draw the conclusion from this that manufacturers and producers are the ones to blame for all our woes, but we as consumers share the responsibility, too. We have proven again and again that we are willing to purchase the thing that tastes the sweetest or costs the least, even when we know it isn’t good for us.

But I digress. The question on the table is… is it really so bad for us?


Let me backtrack a little to how our bodies digest fructose. When fructose gets broken down by the liver, it produces a substance called uric acid. Uric acid is a normal waste product found in the bloodstream, but too much of it in our system can cause insulin resistance and hypertension, and some researchers believe it may also play a starring role in high blood pressure, diabetes, obesity, fatty liver disease, and kidney disease, among other things.

While it is proven that fructose triggers the production of uric acid (no matter where that fructose comes from), it is not clear what makes high-fructose corn syrup so much worse than sugar.

In one study by researchers at Princeton University, two groups of rats were tested — one group was given a mixture of sucrose in water (at about the same concentration as your average soft drink), while the other group was given a mixture of HFCS (at a considerably lower concentration). The results showed the group of rats drinking high-fructose corn syrup gained a significant amount of weight as compared to their sugar-drinking counterparts.

“These rats aren’t just getting fat; they’re demonstrating characteristics of obesity, including substantial increases in abdominal fat and circulating triglycerides,” said Princeton graduate student Miriam Bocarsly. “In humans, these same characteristics are known risk factors for high blood pressure, coronary artery disease, cancer and diabetes.”

One notable difference between regular sugar and high-fructose corn syrup, which may account for some of this disparity, is that the monosaccharides (single sugar molecules, in this case fructose and glucose) found in sugar are bound to one another to create sucrose, which the body has to break apart before digesting, while the monosaccharides in HFCS are not bound together, allowing them to be absorbed more quickly and directly. Fructose molecules that are not bound to glucose are called “free fructose”, and it has been suggested that increased amounts of free fructose may be more of a problem than fructose in combination with glucose.

Studies like this have prompted a lot of confusion for some people, because it leads to the question, if fructose is bad, does that mean fruit is bad?

A growing body of research suggests that it is only an excessive intake of fructose (more than 50g. per day) that may be harmful. The amounts found in most fruits and vegetables pose very little concern when compared the amounts found in processed sugars.

Amount of Fructose in Different Fruits - All About Fructose

One cup of blueberries contains approximately 8 grams of fructose, and about 84 calories. Compare that to the average 12oz. can of soda, which according to a recent study can contain as much as 40g. of fructose and 140 calories.

When you consider that many people consume upwards of 20oz. of soda per day, it is easy to see how a person can quickly get way more than 50g. of fructose.

However, the biggest difference between a piece of fruit and a swig of soda is not the amount of sugar (though that is important — it’s easy to imagine drinking a 20oz. soft drink without a second thought, but much harder to fathom eating ten bananas (the fructose equivalent) in the same way). No, the biggest difference is that a piece of fruit contains vitamins, minerals, antioxidants, and other nutrients our bodies need to function properly and process the sugars it takes in. A can of soda gives none of these things, only sugar. It is empty calories just as surely as alcohol is empty calories.

Honey also comes into question, weighing in at about 38% fructose (the rest being made up of glucose, maltose, and other sugars). Like fruits, honey contains lots of other nutritive benefits besides the sugar. As an added point of interest, one study which compared the effects of honey vs. the effects of purified fructose (in the same concentration as that in the honey) found that the honey had very little negative effect. While the purified fructose caused an elevation of triglycerides and inflammation, the honey made virtually no change.

Of course, too much of any sugars — be they from fruits, honey, table sugar, or HFCS — can be a bad thing. Some people are more tolerant than others, and those who already have diabetes or insulin resistance may indeed have to watch the amount of sugars they take in, even from fruit. For the rest of us, however, if we were to eat a diet of only natural sugars (no added sugars), it would be very difficult to overdose.

Note: Agave is another sweetener that contains a large amount of fructose — depending on the brand, some agave syrups can contain as much as 90% fructose, which is significantly more than the average HFCS ratio. Because of this, agave has come under great scrutiny, and more research is still being done to determine whether it is safe for human consumption.


Okay, so there are a lot of reasons to think too much fructose is bad. Of course, this only addresses one side of the story.

One of the hardest parts about researching subjects like this is that for every study claiming fructose is bad, there is a counter-study saying that the first study is false, or doesn’t have enough evidence. What’s even harder is sorting out the agendas of the people conducting these studies. For instance, when companies like Hershey’s, Pepsi, and Coke start sponsoring programs like the American Dietetic Association, you have wonder at the blatant conflict of interests.

As Hemi Weingarten of The Huffington Post put it, “…that folks, is the endgame for all the snack companies — to sell us more of their products, not less. If they have to spend millions to set up a scientific research center and contribute to doctors and dietitians as well, so be it. Marketing expenses.”

And of course, no one has more vested interest in the matter than the Corn Refiners Association (CRA), who has spent more than $30 million dollars on the popular ad campaign “sweet surprise“. Most of us are familiar with the commercials, wherein one actor portrays a person concerned that their friend is consuming a product containing HFCS, and the friend responds something like, “Why? It is made from corn, is all natural, and has the same calories as honey or sugar. It is nutritionally the same as sugar, and is fine in moderation”.

Some of the big claims made by the CRA are:
1. HFCS is a natural product because it is made from corn, which is natural.
2. HFCS contains about the same amount of fructose as cane sugar does.
3. The fructose and glucose present in HFCS are absorbed by the body the same as any other source of sugar.
4. HFCS is fine in moderation.

These are what the CRA refers to as “vague and unsubstantiated opinions”. I’ve addressed them briefly below.

1. The FDA does not have a general definition of the word “natural”, but the Center for Science in the Public Interest argues that HFCS is not a natural ingredient because it would never appear in nature due to the high level of processing required to produce it. (I think that “not occurring in nature” pretty well meets my definition of the word “unnatural”.)
2. This is based on the claim that HFCS contains 55% fructose, as compared to the 50% present in sucrose. Recent studies which look at the concentration of fructose in popular soft drinks show that most HFCS can range from 55%-65%, which is substantially higher than is stated according to their labels. Even more important is the discovery that some products contain something called HFCS-90, which, as the name suggests, is about 90% fructose. Not all high-fructose corn syrup is made the same.
3. The biochemistry of this is true. The body does absorb glucose and fructose in a similar manner no matter where those sugars come from, however the problem presented with HFCS is that the concentration of fructose is at a level that may be harmful, especially when consumed in the amounts found in the average American diet.
4. This is my favorite one, because it is almost certainly true. The problem arises from the fact that HFCS is found in almost all processed foods, and is nearly unavoidable. You could also argue that red meat and alcohol are fine in moderation, but those foods aren’t hidden within our every-day purchases. While food labels are required to say things like, “may contain soy, wheat, dairy” etc., there is no obligation to tell us if something contains corn or any element thereof.

There are a lot of real, legitimate arguments out there, though. And not just arguments, but questions and concerns.

One very real concern that the Corn Refiners Association has, is that if people believe so strongly that high-fructose corn syrup is bad, it may encourage them to over-eat sweet treats made with cane sugar on the basis that cane sugar is “healthy”. Some manufacturers are switching their products from HFCS to cane sugar with the expectation that consumers will purchase more of them if they believe them to be healthier than they really are.

Other’s are concerned about the accuracy of the statistics. Some studies argue that the estimated amount of fructose people consume is not always well presented, and that more research needs to be done before any conclusive evidence can be found linking it as a primary cause of disease.

And some people are looking for the good side of fructose. One study suggests that certain amounts of fructose can be a good thing in athletes and people who exercise, because fructose can help with fluid absorption and performance.

Oh, and here’s a well thought-out critique of the Princeton rat study I cited earlier. Just more proof of how conflicting all of the information is.

Most of these counter-arguments don’t deny that too much fructose (or sugar of any kind) is a bad thing — in fact, many of them agree that it is — but they argue, rather, the fine semantics of what constitutes “too much”, or whether or not we are, in fact, consuming enough to cause harm. Even the Corn Refiners Association admits that, “just like any other food or ingredient, excessive consumption of sugar can lead to adverse health effects.” …but the question is: what is too much?

I’ll leave that one for you to decide.


One of the biggest arguments against all the “fructose is bad!” studies is this: most of them try to place all the blame for the world’s problems on one single thing. “Fructose causes obesity, heart disease, diabetes, cancer!”, while all of these claims could just as easily be said about other things (and in fact have been said about other things, like meat).

They argue that really, the world is much more complicated than all of that. You can’t pin the world’s problems on this one thing, because you cannot isolate it. In the real world, things aren’t so black and white, and no single food or ingredient can be blamed for everything.

As I said at the beginning of this post, I won’t try to pretend I’m not biased… in fact, I’m pretty thoroughly convinced that great big whopping amounts of fructose are pretty bad… but I don’t think that it’s the cause of all our health problems. Americans also consume great big whopping amounts of bacon, and cheese, and antibiotics, and GMO’s…

I think the number one leading cause of obesity, diabetes, heart disease, etc. is not in our food per se, but in our choices. It can be exceedingly difficult to understand the world of health and nutrition — especially with so many articles telling us what to believe — but I think there is great value in trying to understand it, drawing our own conclusions, and making our own decisions about what we eat and where our food comes from.

Whether you walk away from this with the same conclusions I have or not, I hope that you will have gained something from it. If you’ve made it this far, I can only assume you care quite a lot.

If you have any thoughts or opinions, please feel free to share them in the comments below. I would love to start a discussion and hear what you think!

This is part three in my series on different types of sweeteners, how they’re made, and the impact they have. You can find the other parts of the series here:

Sweet Talk, Part 1                                                                    Sweet Talk, Part 2

, , , , , , , , , , , , , , , , , ,

Still hungry? Try these:

18 Responses to Sweet Talk, Part 3: 9 Reasons Fructose Is Bad For You (FAK Friday)

  1. pewpewzapzap June 16, 2013 at 12:20 am #

    This was an excellent read – balanced, researched, logical, and intelligent. Thank you for the work you put into this, and THANK YOU for encouraging individual research and evidence-based formation of opinion!

    • Willow Arlen June 16, 2013 at 2:05 pm #

      Thank YOU for reading, and for caring! I’m glad you got something out it.

  2. Anonymous June 16, 2013 at 6:53 am #

    Good job! You will find interesting info too about fructose metabolism and storage – different than glucose in very important ways, and about the combined effect of taking in too much fructose and fat together, and effects of all of these in relation to insulin, fat production (lipogenesis) by the liver, and fat storage. Another place for research is on effects of reactive oxygen species and production of reactive oxygen species in relation to metabolism of the different molecules. We still need a lot more research in understanding the development of some of these chronic diseases. There are multiple risk factors that may arise from diet and lifestyle. I agree moderation is key. Remember how juice glasses used to be really small? My guess is that would be a better quantity, or whole fruit instead.

    • Willow Arlen June 16, 2013 at 2:32 pm #

      Indeed! I came across a few articles discussing the effects of fructose in combination with fats and other foods, but it was clear a lot more research needs to be done. There’s so much to know, and right now we understand very little of it. I’m happy to know that research is being done to figure these things out, though. And you’re definitely on to something with the juice glasses… we seem to live in the age of super-sizing, where everything is “bigger is better”. It’s been proven that people will consume more if more is put in front of them, rather than stopping when they’re full or satiated. Back before modern living, when humans were hunter/gatherers, the opportunity to feast was rare but important — storing fat and energy was vital for when food was scarce. Now, in a society where food shortage is almost unfathomable, this once valuable trait is actually a detriment, and it seems the food industry has taken advantage of that. Just a thought.

  3. Unknown June 17, 2013 at 9:49 pm #

    On that chart, aren’t honeydew and cantaloupe switched? o.O If that was published by the USDA, I am so embarrassed for them.

    • Willow Arlen June 18, 2013 at 1:33 pm #

      Well, it isn’t the USDA that needs to be embarrassed, it’s me – and I do know the difference between a cantaloupe and a honeydew. That’s what I get for doing my photo editing at 4am, I guess. I’m glad you caught it, and the photo has been fixed.

  4. shannon weber June 18, 2013 at 10:55 am #

    what a great and informative post! I stay away from HFCS in general, which isn’t so hard to do since mostly i don’t eat a ton of packaged food. It’s sneaky in there, though; just recently i was going to purchase Quaker breakfast squares, thinking it would be a good grab and go snack for when me and stella had to be somewhere in the mornings, and i was shocked to find HFCS as the SECOND INGREDIENT! I wrote them an email telling them how disappointed i was that a company like Quaker would make a product and – tout it as a “breakfast” item no less – that was full of HFCS. GROSS. So i’ll make my own bars and continue to watch out for it.
    i hate the bigger is better attitude with everything. Even our furniture is larger now (i’m assuming to accommodate our larger houses and our larger butts and all the stuff we buy). I’m a big fan of watching my consumption on all levels, but especially about products which are potentially dangerous. FAK friday may be one of my favorite things: you do such a nice job on all your posts, but these especially (coming from someone who knows how long just a normal post takes to throw together!).

    • Willow Arlen June 18, 2013 at 1:39 pm #

      Thanks, Shannon! I really appreciate you saying that, it means a lot to me. And you’re so right about the furniture thing – I recently bought a new fridge, and had to get almost the smallest one I could find (shy of a mini-fridge, of course) jut to fit in my house… and it isn’t a small house!

  5. Abby June 19, 2013 at 2:02 pm #

    I completely agree with you about this! Such a well informed post, the more voices out there trying to educate us all the better!! I recently watched a foodie documentary (I forgot which one) but they had a great point…these days people are eating less food and more “food-like” products. It blew my mind. Now I think twice about snacking on a few pretzels and grab an apple instead! PS. Don’t get me started on GMO’s haha

    • Willow Arlen June 20, 2013 at 4:27 pm #

      Thanks, Abby! That’s a great way to put it… more food-like products, less food. To a certain extend pre-made stuff is fine, but I think my biggest concern is that people be able to choose what they put into their bodies. Whether it’s HFCS or GMO’s or just “natural flavors” or dyes, I think people should be educated enough to make their own decisions. There’s a lot of subterfuge in the food industry that relies on us not being able to think for ourselves, and that’s something I take offense to!

  6. movita beaucoup June 28, 2013 at 1:02 pm #

    I’d like to tell you how much I enjoyed reading this, but THE FIRST PHOTO OF THIS POST HAS ME SO DISTRACTED WITH ITS AWESOMENESS THAT I CAN’T.

    (Plus, Shannon did a pretty awesome job of summing up my feelings. So… ditto.)

    • Willow Arlen June 29, 2013 at 10:56 pm #

      Haha, thanks! It was fun playing around with a different lighting set up.

  7. Sunday Morning Banana Pancakes June 28, 2013 at 6:00 pm #

    You are right this subject can be very confusing with so many different studies and opinions – “not occurring in nature” pretty well meets my definition of the word “unnatural”. I could not agree more – thank you for taking the time to research and share your findings with us Willow, I don’t know how your head wasn’t spinning with all this information!

    • Willow Arlen June 29, 2013 at 10:57 pm #

      Thanks – and you’re very welcome! It was definitely a lot to take in and put together, but I’m so glad I did it… it certainly bettered my understanding of things!

  8. Nichole October 10, 2013 at 5:15 am #

    LOVE this information and it was great to be able to send my Mom here to read it. For some reason she’ll believe what a stranger on the internet says over what I say, even if it’s the same thing! <3 I so wish that we, as patients and consumers, would start demanding that the health industry get out of the pharmaceutical manufacturers' pocket and the scientists out of the fakefood manufacturers' pockets. Keep up the truthing, Willow! It's greatly appreciated. (And please consider doing a FAK on the evilness that is "vegetable oil".)

    • Willow Arlen October 10, 2013 at 3:14 pm #

      Thanks, I’m glad you liked the article! And I agree completely, things are way too muddled in the those industries. I’ll have to look into doing a post on veggie oil – thanks for the suggestion!

  9. Anonymous November 26, 2013 at 4:20 am #

    I think the title of your blog post should really be: ‘9 Reasons High Fructose Corn Syrup is Bad’ because HFCS dominates the entire post. I did enjoy it, don’t get me wrong. I believe that true fructose (not HFCS) from fruit can be quite healthy even when extracted from fruit and used as a sweetener – as long as there’s not more than 10 grams in a serving. I would much rather consume, say, a whey protein shake sweetened with a few grams of fructose than the equivalent amount of sucralose.
    It really is highly frustrating how many contradicting studies are floating around – cholesterol is bad for you…no, it’s good for you; saturated fat is bad for you…no, it’s good for you; fat is bad for you…no, fat is good for you; I could go on and on. The most recent frustration is about water. I can’t count how many times I’ve been told that in order to be healthy I need to consume AT LEAST 64 oz of water per day, but 1/2 my body weight in ounces is best. Upon further research I came across information stating that we don’t need nearly that much water and, in fact, too much water (that amount differs based on weight, activity level, weather, health, etc.) is damaging to our health because it upsets the delicate balance of potassium and sodium in our bodies. WTH?

    • Willow Arlen November 26, 2013 at 6:27 am #

      Hey there — thanks for the comment! You’re right, this post focuses very strongly on HFCS. That is because it is the primary source we have of really concentrated fructose (besides Agave, which, while organically occurring, has even more fructose than most HFCS). As you said, the fructose naturally found in fruit is all well and good. And I agree 100%, I would take fructose over sucralose (or most other artificial sweeteners) any day!
      That thing about the water is just insane! Too much water is not only dangerous, but it can be deadly if you truly drink to much (I remember reading an article about a runner who died from over-hydrating after a marathon, once). While I think it’s true that many people are not drinking as much as they should, those numbers are just absurd — just another great example of some of the crazy stuff out there. Don’t believe everything you read!

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Read previous post:
Barbecue Bacon Cheeseburger – Man-Food To The Max

I can't remember the last time I had a burger. A real burger, I mean, not the veggie kind. It...