Q&A on Yacon Syrup, FOS, Fructose & More

Updated on March 5, 2019
JulesH profile image

Jules is a writer, blogger, journalist, reader, and traveler.

A fully grown yacon plant in Lima, Peru
A fully grown yacon plant in Lima, Peru | Source

When Dr. Oz recommends a product, many people are willing to give it a try. And when the product also has something to do with weight loss, you can pretty much guarantee America’s attention.

In his show earlier this week, Oz spoke about yacon syrup, a natural sugar substitute that has a trait uncommon to most sweeteners – it might also contribute to weight loss. The syrup is extracted from the roots of a yacon plant, native to the highlands of Peru. Locals have used it for many centuries as part of their diets, including it into their salads and desserts, or simply eating the fruit by itself.

The syrup derived from the tuber plant is starting to make its way onto American tables, thanks to such qualities as low caloric value and low glycemic index ranking. Studies conducted so far, including the one done by Oz, have shown the syrup to contribute to faster satiation, improve the work of the digestive system and boost the immune system. It has many other potential health benefits, such as reduction in LDL cholesterol levels and constipation relief. It doesn't raise blood sugar levels, making it a good option for people with diabetes.

After yacon syrup received a huge popularity boost thanks to Oz’s show, I’ve seen many people discussing its possible pros and cons in different health sites. After all, you have to take everything with a grain of salt these days, especially when it comes to various “diet miracles.” I’ve noticed a similar trend in many of these online discussions – a lot of people seem to be confused about the high FOS content of the syrup, taking it for high fructose level and automatically dismissing the sweetener as not being so healthy after all. I’ve also seen people debate about the level of processing involved when the syrup is extracted, and how the processing affects its nutritional value.

So I decided to do a little research into these topics. Is yacon syrup high in fructose? Or is it just a common misunderstanding, caused by "fructooligosaccharides" and other technical terms unfamiliar to many of us? That’s one thing I wanted to know. But let’s start with figuring out the difference between FOS and fructose.

The tuber harvest from one yacon plant
The tuber harvest from one yacon plant | Source

Are FOS and Fructose the Same Thing?

Based on my research, the answer to that question is “no.” Fructose is a simple sugar that gets metabolized in the liver. Fructooligosaccharides are soluble non-digestible carbohydrates, which means that they are also a type of sugar, but they are not metabolized in the liver. In fact, they pass through the entire digestive system practically unchanged, which is the reason why they are considered to be so low in calories.

Before reading this, did you think FOS and fructose were the same thing?

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The main difference is seen when FOS reach the colon. While regular sugars tend to feed bad bacteria in the colon, FOS has the opposite effect. It is considered a prebiotic, which means that it is the food for probiotics, or the beneficial bacteria in our colon. There it gets selectively “eaten” by probiotics, which use it as a source of energy and food. FOS can be essentially considered a soluble fiber, so the level of FOS in yacon syrup should be viewed as the level of fiber, rather than the level of sugar. Depending on the variety of yacon plant that’s used in the production of the syrup, the FOS level in it can range from 10% to as much as 50%.

Are FOS and Inulin the Same Thing?

You will often see these two terms used interchangeably, and the reason is that they are practically the same thing. The only difference between the two is their polymer chain length. You might also find FOS under such names as helenin, neosugar, Atlanta starch, alanin, alant starch, dahlin or diabetic sugar.

Yacon flower
Yacon flower | Source

Is FOS Really that Good for You?

From what I’ve found, the answer to that question is “it depends.” After reading all the positive marketing about FOS that’s been circulating online lately, you might want to jump on a bandwagon and buy a yogurt or another product that’s labeled as FOS-enriched. Don’t be too quick to do so. The truth is, very little research has been done on the effects of FOS on humans, especially the type of FOS that comes as a food additive, rather than being naturally found in plants.

This leads to several issues. For one, the scientists haven’t quite proven that FOS only feeds the good bacteria. In addition, the effect of FOS on yeast growth hasn’t been studied much yet, although it is known that some species of yeast can use FOS for energy. And because bacteria are known to easily adjust to pretty much any fuel source, chances are they could adapt to FOS, too. So far, scientists have only looked into the effect of FOS on several microbes, while its interaction with hundreds of them still remains to be studied.

Structural formula of inulin
Structural formula of inulin | Source

This doesn’t mean that you should not eat natural foods rich in FOS, such as Jerusalem artichoke, onions, leeks, asparagus and soybeans, among others. What you need to keep in mind when comparing it to FOS in yogurt, is that the latter is likely to be highly processed, and is no longer the same substance that our bodies are used to when it comes in the form of plants. This leads me to the next point. How about the syrup? To what extent is it processed and what effect does the processing have on the yacon plant’s natural health benefits?

Yacon rootstock with storage roots, Peru
Yacon rootstock with storage roots, Peru | Source

How Is Yacon Syrup Processed?

I got interested in this question after seeing it asked by people in several forums. Most of them were wondering whether the syrup was processed at high temperatures, which happens to most liquid sweeteners, causing them to release a lot of high fructose.

As it turns out, yacon syrup extraction process is pretty simple. The roots are crushed and milled, with all the raw juices squeezed out. The water from the juice is then evaporated to reach the final dense concentration of the syrup. The syrup is boiled, which helps gets rid of some unpleasant tastes and gives the final product a more caramelized texture. Boiling doesn’t affect FOS, as long as the temperatures do not exceed 120°C degrees. After that, FOS starts to break down into simple sugar forms, also known as free fructose.

Are you planning to give yacon syrup a try?

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For this reason, always check the label when you are buying your syrup. All reputable brands will include information such as the temperature at which the processing was done. Many varieties will show 140°C degrees, but you should try to stick with the ones that are within a 120°C limit. Remember that the higher the processing temperature, the less FOS and the more free fructose the syrup is likely to have.

What is the Level of Free Fructose in Yacon Syrup?

Processing does seem to increase the level of free fructose in the syrup somewhat, as compared to such a level in the plant itself. Immediately after harvesting, yacon only has a 1.6% level of fructose. If it stays in the sun for six days, the level goes up to 3.5%. Generally, though, the plants don’t keep very well and don’t transport well either, so the extraction facilities are usually located close to where yacon is cultivated, and the processing starts right after cultivation.

Fructose | Source

Depending on the variety of the plant and the temperature at which it’s processed, free fructose levels in yacon syrup range from 7.9% to 25.4%. This means that even at its highest level, it is still lower than the amount of fructose in most sweeteners. When compared, agave has 30% to 80% free fructose, depending on its variety, honey has 40% to 45%, and high-fructose corn syrup has 42% to 90%.


Considering that FOS fuels probiotics, I wonder what happens if I take a spoonful of yacon syrup in combination with a probiotic I regularly take. I’ll probably live in the bathroom. But that’s a story for another time.

So is yacon syrup a secret solution to weight problems? I wouldn’t be too quick to judge. My understanding is that only a handful of studies have been conducted so far on the subject matter, and none of them were controlled. The majority of the studies that did show positive results were done on animals rather than humans. I would like to see more evidence before I decide on seriously introducing this stuff into my diet, especially considering the fact that it’s not that cheap.

Yacon root
Yacon root | Source

Furthermore, I think it’s common sense that the actual fruits that all of these syrups are extracted from are always a better choice. You get the nutrients in their natural form, which is something our bodies know how to work with, as opposed to introducing something new, which takes adjusting to and might not make our digestive systems all that happy in the long run. The problem with that, of course, is that yacon as a plant is not easily found in North America.

But all things considered, I know that people are looking for sweetener substitutes, and that’s what it’s all about. Not many will go out of the way to find a rare fruit, which can be substituted for asparagus (not as high in FOS, but still pretty good). You can’t slice up the fruit and drop it in your coffee. Well maybe you can… weirdo.

Did the article answer any of your questions about yacon and its syrup?

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While I don’t sweeten any of my drinks, I don’t mind a cookie every now and then, and if yacon syrup is that much better that other sweeteners, then why not, I’ll bake with it. Wait a minute. There won’t be much FOS left in it after a few minutes at 350°F (177°C), so what’s the point of paying more? I guess it is only really worth it if you are willing to use the syrup in other ways, such as mixing it into your yogurt or iced tea, for instance, or maybe even replacing honey to make a “yacon-syrup-mustard” dressing (get it?). Keep in mind that you shouldn’t exceed 20g per day, though, or else you might get some serious flatulence and diarrhea.

Despite some of the cons, I’d like to know more about how all of this works, so I’ll be keeping my eye open for more studies. I hope the scientists research the heck out of this scientifically neglected and underutilized product, and do it soon. Although unlike me, it doesn’t look like a whole lot of people will be sitting around and waiting for new studies. I checked some online stores selling yacon syrup, and it’s currently sold out in the majority of them. Speaking of the effect Dr. Oz has on America...

Disclaimer: I am in no way related to medical profession, and this article is based purely on my research and my desire to know more about healthy foods and lifestyle choices. If you think any of the statements are incorrect, please let me know in the comments and refer me to a good source, so I can fix them.

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This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.


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    • profile image


      13 months ago

      Thank you for answering my question:"Does boiling Yacon turns indigestible sugars into fructose." As long as it never went above 120 degrees while making the syrup!

      I appreciated your hesitation to just rubber-stamp this as "100% Healthy" and added your reservations to the article.

    • profile image


      4 years ago

      Thanks so much for writing this article. I have been searching for low fructose sweeteners (don't talk to me about stevia, I hate it, lol) and didn't understand FOS until now. Thanks for helping me find an alternative.

    • Shades-of-truth profile image

      Emily Tack 

      5 years ago from USA

      I actually love yacon syrup!

    • profile image


      5 years ago

      I've been using the syrup for about 4 months. I drink and ferment my own kombucha and water kefir, I avoid sugar and carbs and I believe I have a good amount of healthy gut flora, but even with that I still had to slowly introduce my body to it. First time use had me running to the bathroom. I will say that for me, I do experience a marked decrease in appetite when I use it.

    • profile image


      6 years ago

      This is really comprehensive...thank you so much.

    • wqaindia profile image

      Ashok Goyal 

      6 years ago from 448 Dalima Vihar Rajpura 140401 Punjab India

      Interesting in depth study on FOS. http://webquestionanswers.com/

    • profile image

      Alexandre França 

      6 years ago

      Thank you, great info!


    • Thelma Alberts profile image

      Thelma Alberts 

      6 years ago from Germany and Philippines

      Congratulations on the HOTD! I have not heard about this yacon plant or its syrup. Thanks for sharing this very interesting and informative hub. Well done!

    • cathylynn99 profile image


      6 years ago from northeastern US

      an FOS is an FOS, whether made in a lab or extracted from a plant.

    • john000 profile image

      John R Wilsdon 

      6 years ago from Superior, Arizona

      I think that your conclusions are right on. Nice to see someone "objectivily" commenting about the research. Yes, the fruit "might" be very useful. I also appreciate the list of references you sought.

      I have friends and family members with diabetes, as many readers have also. Any word of alternatives for sweetening is always welcomed. If the alternatives are determined to be safe, I am all for it. The devastation on the body of diabetes is formidable.

      At the same time, an oncologist who treated my mother was dead set against fructooligosaccharides.

      This hub contributes greatly, thank you.

    • profile image


      6 years ago

      Very insightful and unique Article!

    • profile image


      6 years ago

      Congrats on your Hub of the Day award for this info and thanks for the interesting introduction to yacon syrup.

    • Christy Kirwan profile image

      Christy Kirwan 

      6 years ago from San Francisco

      Great Hub, Jules! I've never heard of yacon syrup before reading. I really like how you stick to the facts and present your research in an unbiased way (and even offer a few ideas for using it without cooking so that it's actually effective). Very thorough!

    • profile image


      6 years ago

      For Sweeteners would you recommend rice syrup which is made of glucose and maltose?


    • JulesH profile imageAUTHOR


      6 years ago

      Thanks, Kukata and DoctorScottHealth!

    • DoctorScottHealth profile image

      Dr. Scott McLeod. PharmD 

      6 years ago from Los Angeles

      I stumbled upon this article out of pure chance. I'm not really a Dr. Oz follower so I'm glad I could be introduced to this new sweetner fad. Great job on a very informative article that covered a lot of ground. Thanks!

    • Kukata Kali profile image

      Kukata Kali 

      6 years ago

      Great info!

    • JulesH profile imageAUTHOR


      6 years ago

      Thank you, Paul!

    • tsuprukblogs profile image


      6 years ago from Parma Heights, OH

      I really enjoyed reading this Hub. Great from start to finish. Great work.



    • JulesH profile imageAUTHOR


      6 years ago

      Glad you enjoyed it, CraftytotheCore! Your name made me want to go check out your stuff too... I love crafty stuff ;)

    • CraftytotheCore profile image


      6 years ago

      This is an awesome article. So informative and interesting. I have never heard of this before. I have eaten different foods/drinks from Peru which are all lovely and so healthy.

    • JulesH profile imageAUTHOR


      6 years ago

      Thank you, erorantes!

    • erorantes profile image

      Ana Maria Orantes 

      6 years ago from Miami Florida

      Miss. Jules , I like your article. Thank you for your good work.

    • JulesH profile imageAUTHOR


      6 years ago

      Thanks, quicksamba! And thanks for being the very person to comment on my very first hub! :) I will try to publish more stuff like this, already got a couple of ideas in the works.

    • quicksamba profile image

      Jack Quick 

      6 years ago from Las Vegas, NV

      Very useful article. Thanks!


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