Is fructose really that harmful?

Firstly, people must understand that fructose, like glucose, is a simple sugar, which is contained in sugar and in high fructose corn syrup. While glucose is absolutely vital for the life of human cells, fructose isn’t. Glucose is not only found in a number of starches, but is also produced by the human body cells, as well as by any other cell in the world.

In other words, glucose is essential for life, while fructose, according to some, could actually be harmful, and excess amounts of it can even be dangerous.

The logic behind this claim is that humans do not actually produce fructose, and historically have not been known to consume it, except when eating really ripe fruits at the peak of the season. Still again, the fructose in the fruits, honey and vegetables, which we all consume is not in the harmful level when fresh fruits and veggies are consumed in “normal” and recommended quantities.

The problem with fructose is that it is metabolized by the human body in a very different way than glucose is. Whilst every human cell needs and uses glucose, the only human organ, which can metabolize excess quantities of fructose is the liver.

The thing is that when people overindulge in fructose, the liver starts having problems coping with all the metabolizing, and this triggers the transformation of fructose into triglyceride, which is a form of fat.

This, according to some, can trigger the onset of some of the most serious and even life-threatening health problems in the modern world, such as: type II diabetes, heart disease, obesity and possibly cancer.

Excess levels of triglycerides can lead to the liver cell and liver functioning damage, as well as an increased risk of developing plaque in the blood vessels, which we know can lead to serious problems and even fatal ones, such as strokes and heart attacks.

A study, published by the Journal of Clinical Investigation a few years ago, compared the effects of glucose and fructose consumption on the metabolism and the possible health implications they have. It concluded that the two simple sugars had a different effect on the metabolism, with excess fructose consumption actually leading to an increase of the “bad” LDL Cholesterol levels as well as insulin sensitivity levels in overweight subjects.

In 2013, another study with a similar subject matter concluded that the intake of sugar in the US has increased by more than 40% since the beginning of the 19th century, and the implications of this increase, were the main subject of this particular study. According to Dr. Robert H. Lustig, who is a professor of pediatrics and an obesity expert, the Americans used to consume about 15 grams of fructose back in the early 1800’s, while in the 21st century, the consumption has increased up to an average of 73 grams per day.

The shocking revelation that about 50% of the added sugars, which the US population consumes comes from soft drinks and fruit drinks, and the immense increase of consumption of these popular beverages has led to the risk of diabetes, obesity, cardiovascular disease and metabolic syndrome, plus the risk of nonalcoholic fatty liver disease, an increase of uric acid and gout in men.

Not only that, but it is believed that sugar could actually be addictive, causing cravings and withdrawal-like symptoms when taken out of the diet.

Even though people may not feel the symptoms of addiction when consuming sugary drinks and snack foods with added sugar, this excess fructose can cause blood sugar swings as well as unwanted weight gain because of the empty calories they contain.

The excessive consumption of fructose affects the appetite-regulating hormones, which leads to the by-passing of the human appetite signaling mechanism of the human body, and leaves the person constantly hungry and unsatisfied.

In fact, since it has a relatively low glycemic index, fructose was considered a better alternative to table sugar until just about a decade ago, but the American Diabetes Association, along with experts in the field of nutrition, have denied this and have pointed out the consumption of excess amounts of fructose can overwhelm the liver and the entire metabolism.

Normal amounts of fructose are naturally found in some fruits and vegetables, but the major sources of fructose, which can cause health problems, is considered high fructose corn syrup (HFCS), which is found in the majority of the most popular soda drinks in sometimes dangerously high levels.

The over-consumption of sodas with high content of fructose has been found to increase the risk of infants and youngsters developing diabetes type II at an early age.

The problem with the high fructose corn syrup is that it is affordable and can be found just about anywhere in the US, mainly because of the corn subsidies.

And even if a person chooses to stay away from the fructose-filled soft drinks, there are some and in some cases large quantities of fructose found in the majority of packaged foods which include sugar. Some foods which have large quantities of fructose are: breakfast cereals, baked packaged goods, candies, jam, sweetened yogurt, chocolate milk, and so on. Something which not everybody is probably aware of is that even the concentrated “healthy sweeteners” such as Agave syrup include large amounts of fructose, in this case up to 90%.

Even though there is no clear-cut scientific evidence which directly links fructose to weight gain, there are some studies which link this simple sugar to particular hormones which regulate the body weight. On the other hand, a large number of scientists and nutritionists deny that there is such a correlation, or at least they are not willing to agree that fructose is the only and the biggest reason for the growing problem with obesity in the US, and that high fructose corn syrup is actually as safe to consume as is corn sugar, corn syrup, sucrose or invert sugar.

The suggestion given by some of these experts is to limit carbohydrate intake to up to 50% of the complete daily diet, and ensure that the majority of these carbohydrates come from veggies and whole grains rather than processed foods and foods with added sugar.


  • Gaby, Alan R. “Adverse effects of dietary fructose.” Alternative medicine review 10, no. 4 (2005): 294.
  • Stanhope, Kimber L., Jean Marc Schwarz, Nancy L. Keim, Steven C. Griffen, Andrew A. Bremer, James L. Graham, Bonnie Hatcher et al. “Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans.” The Journal of clinical investigation 119, no. 5 (2009): 1322-1334.
  • Bray, George A. “Energy and fructose from beverages sweetened with sugar or high-fructose corn syrup pose a health risk for some people.” Advances in Nutrition: An International Review Journal 4, no. 2 (2013): 220-225.
  • Lustig, Robert H. “Sugar: The Bitter Truth.” YouTube. July 30, 2009. Accessed October 7, 2014.
  • Avena, Nicole M., Pedro Rada, and Bartley G. Hoebel. “Evidence for sugar addiction: behavioral and neurochemical effects of intermittent, excessive sugar intake.” Neuroscience & Biobehavioral Reviews 32, no. 1 (2008): 20-39.
  • Page, Kathleen A., Owen Chan, Jagriti Arora, Renata Belfort-DeAguiar, James Dzuira, Brian Roehmholdt, Gary W. Cline et al. “Effects of Fructose vs Glucose on Regional Cerebral Blood Flow in Brain Regions Involved With Appetite and Reward Pathways. Fructose Consumption and Weight Gain.” JAMA 309, no. 1 (2013): 63-70.
  • “Glycemic Index and Glycemic Load for 100 Foods.” Harvard Health Publications. Accessed October 7, 2014.
  • Ventura, Emily E., Jaimie N. Davis, and Michael I. Goran. “Sugar content of popular sweetened beverages based on objective laboratory analysis: focus on fructose content.” Obesity 19, no. 4 (2011): 868-874.
  • American Chemical Society. (2007, August 23). Soda Warning? High-fructose Corn Syrup Linked To Diabetes, New Study Suggests. ScienceDaily. Retrieved October 7, 2014 from
  • Chang, Louise. “Fructose and Weight Gain: A Bad Rap?” WebMD. April 10, 2006. Accessed October 7, 2014.

11 thoughts on “Is fructose really that harmful?

  1. Don’t listen to this bullshit or any other type of fad thing.

    Watch what you eat, be active, and have that odd dirty meal every now and then and you won’t die young.

    So long as you don’t overeat and you’re physically active, you’ll be healthy and live a long, happy life instead of worrying each day about how sugar to consume.

    1. Everybody has different lifestyles and needs. You also tend to forget that we eventually don’t make the choices what we eat. The food industry does.

      Advertising their products backed by faulty science that it’s healthy and therefor you should buy it. Almost everything you buy in the supermarket has added sugar of which you don’t know of, because of great amount of sugar types and names. Most people don’t even know what a healthy meal is.

      Heck I’m even talking about my own experience. I thought I was living a healthy life, because I was doing just everything you said: Being active, eat dirty meals now and then. But I still was overweight. When I cut off any refined sugars in my diet I dropped 25 kg (55lbs) in body fat, my skin looked more healthier, I got more energy and I have no more food cravings.

      Friends/family come to me and ask how I did it, because THEY JUST DON’T KNOW… So let these studies and scientists do their job by informing us what is going on and why more and more people are getting obese. The professor in the video is doing a good job informing us about how to make right choices when it comes to food even if you are not visually overweight. Or did you forget/don’t know about visceral (or internal) body fat, insulin spikes and resistance, the effects of sugar on your skin, etc….

      Your promise of not dieing young by doing all the things you said means jack shit in this time of era. Independent scientists/researchers need to study these effects, because the way we are heading right now is an uninformed (even clueless) overweight/obese unhealthy human race with food companies getting too much control over consumer consumption. People deserve to know what they eat and what effects it has on their body…

  2. Not to be overly dramatic, but, we all die. I’m going to eat sweets because they’re delicious. I don’t want to lay on my death bed wishing I enjoyed life more.

    Plus, we’ll probably see a report in 20 years that sugar is actually not that bad for you. ie.

  3. Good article. One thing needs to be clarified. The issue with all edible sugars is DOSAGE and accompanying nutrients.

    The problem with the high fructose corn syrup in a two liter bottle of soda pop is that there is a vast amount of it “per serving” (even putting aside the true size of a typical serving), and that there are no accompanying nutrients.

    This would be equally true of glucose, which is, in fact, often used as a sweetener – “dextrose” is the same thing as glucose. The body requires a well regulated level of blood glucose for sustainable, healthy functioning, and in fact, you will go into a coma and die if it falls below a certain level and is not corrected. Nevertheless, consuming vast amounts of glucose as a sweetener makes no sense.

    The fructose in fresh fruit is generally not harmful, because the absolute amount in a serving of fruit is modest, and the fruit typically provides numerous other nutrients.

    There is no daily requirement for sugar, but a diet that obsessively avoids sugars in fruits and vegetables, regardless of actual absolute amount, would be a poor diet and would need to be supplemented to prevent malnutrition.

    It really is mainly a question of quantity.

  4. That’s funny. Everything we eat gets broken down into simple sugar to fuel our brains and bodies.

    Next these same folks will tell us, “don’t believe your bodies, sex is horribly bad for you and really unenjoyable too.”

  5. There’s no such thing as unhealthy sugar; only the amounts make them bad for you. Same with salt, or anything else your body actually needs but we tend to overdo.

  6. There has been plenty of times where sugar, along with coffee, has prevented me from killing others. This proves that sugar can be very healthy on a persons longevity.

  7. Has anyone kept track of all the things we are supposed to research, be experts on, and live on a daily basis? Do you think all the ‘experts’ care that no one has the time for that?

    Eat the right sugar, don’t eat sugar, no eat the right amount of sugar.

    Don’t be out in the sun, no you need sun, just use sunscreen, use the right sunscreen, no not that sunscreen, the other one, you know that one that costs 4 times as much.

    You can eat healthy on a budget, but really only if you live near a farmers market and devote chunks of time to carefully monitor the entire food situation in your city.

    Don’t spend too much time by yourself, don’t spend so much time around other people.

    Don’t spend money. Here’s what you should buy, now that you’ve bought it, here’s how to re purpose it.

    Be skinny, don’t be too skinny. Be healthy! Your doctor says you’re healthy? How can that be? I can’t count your ribs or see a clearly defined clavicle.

    Coffee is good, coffee is bad, coffee is a superfood, coffee is poison.

    There is no winning. Can’t we just use moderation, be ourselves, splurge once in awhile and make the most of what little time there is in life?

  8. Since glucose is the preferred fuel for the cells with the brain, being a glucose consumption factory, and with the body having numerous back up systems to provide glucose, the vital fuel of life, to the cells when it drops too low in the blood stream, such as liver glycogen and then the breaking down of muscle proteins to turn into glucose, nature must have made a mistake by choosing its primary fuel as being something so dangerous as glucose.

    This statement is meant to show the absurdity of sugar as being unhealthy.

    Or is it that nature didn’t know what it was doing in choosing glucose as the main cellular fuel and providing numerous backup systems to provide glucose, not fat and not protein, as the preferred fuel for sustaining cellular energy and life.

    1. Refined sugar is not nature. And with any billion dollar industry you can expect the trolls. Sugar is addictive and dangerous. Just ask any diabetic amputee in a wheel chair wheeling themselves to a vending machine!

  9. Bit by bit, I’ve drastically reduced my sugar consumption. I still can’t resist a bit of chocolate now and again, but I stopped having sugar on breakfast cereal and in tea/coffee long ago. I quit soft drinks (with very occasional exceptions). I probably still have far too much sugar – it’s in damned near everything – but I’ve easily halved my intake, if not more.

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